Why airlines make flights longer on purpose(bbc.com)
bbc.com
Why airlines make flights longer on purpose
http://www.bbc.com/capital/story/20190405-the-secret-about-delays-airlines-dont-want-you-to-know
148 comments
The idea that padded schedules leave airlines with no reason to be efficient is idiotic. It’s a heavily capital-intensive industry with razor-thin margins that has historically been a bad place to make money. There’s even a classic joke about it: “How do you make a small fortune in the airlines? Start with a large fortune.”
This is the industry that generated the famous story where American saved $40,000/year by going from two olives to one in their in-flight salad. United saved $300,000/year by printing their magazine on lighter paper. If you work at an airline and find a way to shave off a dime in fuel costs per flight, you’ll get articles written about you. And we’re supposed to believe that these companies don’t care about wasting fuel now that their schedules are padded out a bit?
This is the industry that generated the famous story where American saved $40,000/year by going from two olives to one in their in-flight salad. United saved $300,000/year by printing their magazine on lighter paper. If you work at an airline and find a way to shave off a dime in fuel costs per flight, you’ll get articles written about you. And we’re supposed to believe that these companies don’t care about wasting fuel now that their schedules are padded out a bit?
The iead that airlines have no reason to be efficient in it of itself is idiotic. It is an incredibly competitive industry, and the lengths to which airlines go to explore every possible margin is enough testament of that.
To add to your list of examples. KLM, for instance, was one of the first to introduce a system that would allow certain flight data to be uploaded into the flight computer as opposed to be requiring the pilots to enter it by hand. Other than fewer errors, they touted potentially saving pilots a couple minutes of data entry as one of the chief gains of the system.
To add to your list of examples. KLM, for instance, was one of the first to introduce a system that would allow certain flight data to be uploaded into the flight computer as opposed to be requiring the pilots to enter it by hand. Other than fewer errors, they touted potentially saving pilots a couple minutes of data entry as one of the chief gains of the system.
I generally avoid the word "idiotic", but it fits here. Can we flag articles for stupidity?
Article tl;dr -- Airlines used to get from airport to airport faster. Airlines used to be late a lot of the time. Airlines increased their estimated flight times in order to achieve higher on-time percentage. The reason they did this instead of just being faster is that they love using more fuel.
I'm not anywhere near the airline industry myself. The next time I see misreporting on my own company or industry I'll look back at this and remind myself it could be worse.
Article tl;dr -- Airlines used to get from airport to airport faster. Airlines used to be late a lot of the time. Airlines increased their estimated flight times in order to achieve higher on-time percentage. The reason they did this instead of just being faster is that they love using more fuel.
I'm not anywhere near the airline industry myself. The next time I see misreporting on my own company or industry I'll look back at this and remind myself it could be worse.
The increased the time so that they won’t be fined for not being on time.
How does that reduce costs, though?
perhaps a minute or two less of running the engines?
Switching to ipads for the pilots resulted in saved fuel costs as well (yet another article). The populist notion that corporations are just evil things out to do stupid things really clouds rational thought. :(
> The populist notion that corporations are just evil things out to do stupid things really clouds rational thought. :(
That's not the populist notion on corporations at all. The populist notion is that corporations' incentive structure, set by their board/leadership, causes them to act at the expense of rank and file workers and consumers.
That's very different than "evil" or "stupid".
That's not the populist notion on corporations at all. The populist notion is that corporations' incentive structure, set by their board/leadership, causes them to act at the expense of rank and file workers and consumers.
That's very different than "evil" or "stupid".
It is still misguided. The idea of capitalism works because everyone is acting in their self-interests all the while everyone benefits from each other's work. The first thought that should come to mind where you see a corporation that's successful is that many people choose to do business with it and therefore it is generating them plenty of value.
Corporations are not an emergent property of the universe.
They are models, specifically sanctioned by law, that are organized around particular sets of interests.
Just because there are subsets of people whose self-interest is aligned with particular corporations' doesn't mean that those interests are aligned with the self interest of everyone, or even a majority of people.
And this isn't to say that there isn't an important role for corporations to play in the world, but to suggest that their form and function is the result of everyone acting in their self interest is oversimplifying things dramatically.
They are models, specifically sanctioned by law, that are organized around particular sets of interests.
Just because there are subsets of people whose self-interest is aligned with particular corporations' doesn't mean that those interests are aligned with the self interest of everyone, or even a majority of people.
And this isn't to say that there isn't an important role for corporations to play in the world, but to suggest that their form and function is the result of everyone acting in their self interest is oversimplifying things dramatically.
Man solves all problems by pretending there simply are none
Yes, in reality, corporations are evil things trying their best to be smart!
>There’s even a classic joke about it: “How do you make a small fortune in the airlines? Start with a large fortune.”
"The secret to become millionaire is to be a billionaire and buy an airline"
"The secret to become millionaire is to be a billionaire and buy an airline"
> As for CO2, the plane flying slower is more fuel-efficient.
It's counter-intuitive, but an aircraft can be more efficient at higher airspeeds. The reason for this is that, unlike a ground vehicle, an aircraft in level flight must expend energy generating lift to balance its weight. This loss of energy shows up as lift-induced drag [1]. As airspeed increases, the losses to lift-induced drag decrease, while the losses to aerodynamic drag increase. Where the point of minimum total drag lies depends on several factors including weight and altitude. See [2], which contains a chart for a generic aircraft which is 5% less efficient at Mach 0.72 than it is at Mach 0.80.
1. https://en.wikipedia.org/wiki/Lift-induced_drag
2. http://atmseminar.org/seminarContent/seminar11/papers/481-Je...
It's counter-intuitive, but an aircraft can be more efficient at higher airspeeds. The reason for this is that, unlike a ground vehicle, an aircraft in level flight must expend energy generating lift to balance its weight. This loss of energy shows up as lift-induced drag [1]. As airspeed increases, the losses to lift-induced drag decrease, while the losses to aerodynamic drag increase. Where the point of minimum total drag lies depends on several factors including weight and altitude. See [2], which contains a chart for a generic aircraft which is 5% less efficient at Mach 0.72 than it is at Mach 0.80.
1. https://en.wikipedia.org/wiki/Lift-induced_drag
2. http://atmseminar.org/seminarContent/seminar11/papers/481-Je...
Sure, but nowhere do I see any indication that the airplanes are purposely being flown below their maximally efficient speed? Most of my flights are arriving early these days (I guess because of the padded schedules). They're certainly not lingering in the air any longer than they have to, because lingering in the air costs money that they don't want to unnecessarily burn.
As another commenter pointed out, even if the gate isn't ready yet, there's always room to wait somewhere on the taxiway (this has happened to me a few times recently). They'd rather wait on the ground with the engines idling than circling around in the air with the engines running at speed. Plus, it's not like gate availability is affected by schedule padding anyway; there's only so many gates at an airport, and they always are trying to turn over planes as fast as possible.
As another commenter pointed out, even if the gate isn't ready yet, there's always room to wait somewhere on the taxiway (this has happened to me a few times recently). They'd rather wait on the ground with the engines idling than circling around in the air with the engines running at speed. Plus, it's not like gate availability is affected by schedule padding anyway; there's only so many gates at an airport, and they always are trying to turn over planes as fast as possible.
It’s likely that part of the reason you’re arriving earlier (especially if flying west to east) is due to higher jet stream velocities in the winter. This increases the ground speed of the plane even if the optimal indicated airborne airspeed is being maintained.
A planes lifespan is measured in flight hours. As soon as you're on the ground, it isn't really depreciating much.
Sure, aircraft can be more efficient at higher speeds, but then when speeds pass a certain threshold, drag starts to dominate and efficiency drops like a rock. There's a sweet spot, and it's certainly less than the plane's top speed.
...this is exactly what the commenter you’re replying to said, except also with nice charts/graphs showing the sweet-spot for various aircraft...
Except the comment was making a point that was irrelevant for the domain in consideration (typical aircraft speeds for commercial flight).
It's like if someone said, "going a little slower on the highway [typically ~60 mph+] saves on fuel" and someone pedantically ButAkshully'd that cars are more efficient at 40 mph than 30 mph because of engine performance.
Edit: Ironically, I'm the one normally promoting my "Scylla-Charybdis heuristic", that you should be able to identify when tweaking a parameter goes too far. But here I think the context of the tweak was clear enough that this caveat was a distraction from the core point.
It's like if someone said, "going a little slower on the highway [typically ~60 mph+] saves on fuel" and someone pedantically ButAkshully'd that cars are more efficient at 40 mph than 30 mph because of engine performance.
Edit: Ironically, I'm the one normally promoting my "Scylla-Charybdis heuristic", that you should be able to identify when tweaking a parameter goes too far. But here I think the context of the tweak was clear enough that this caveat was a distraction from the core point.
That’s a theoretical aircraft, not an actual aircraft.
In practice they save fuel by flying slightly slower. But, their are many other considerations like weather that cause airlines to fly slightly outside of optimal altitudes and speeds.
In practice they save fuel by flying slightly slower. But, their are many other considerations like weather that cause airlines to fly slightly outside of optimal altitudes and speeds.
> Here the airlines are doing pretty much exactly what I, as a passenger, want, which is to predictably arrive at an airport by a certain time more often.
I was flying to Edinburgh for Christmas a couple of years ago, we were slated to leave at 9pm and arrive at 9am (7 hour flight + 5 hour time difference, made sense).
Then the plane was late getting to us, and they didn't arrive until 9:30, they quickly kicked out the passengers, then the new crew climbed aboard to start cleaning. By 10pm, we were still waiting in the terminal. at 10:45, we were finally allowed to board the plane, and after a couple of minutes it backed away from the gate and taxied to the runway, where we sat for over an hour. We were the last scheduled departure, and when the plane arrived late, the de-icing crew had gone home. We didn't leave until after midnight.
And we arrived... at 8:45 am, 15 minutes earlier than scheduled.
I slept, so I'm not sure if we hit some massive jet stream, or a black hole, or what, but that was the day that I stopped believing flight times.
Edit: Took this photo[1] waiting outside the hotel for an early check-in.
1: https://megapickles.photo/2017/12/25/reflections-of-edinburg...
I was flying to Edinburgh for Christmas a couple of years ago, we were slated to leave at 9pm and arrive at 9am (7 hour flight + 5 hour time difference, made sense).
Then the plane was late getting to us, and they didn't arrive until 9:30, they quickly kicked out the passengers, then the new crew climbed aboard to start cleaning. By 10pm, we were still waiting in the terminal. at 10:45, we were finally allowed to board the plane, and after a couple of minutes it backed away from the gate and taxied to the runway, where we sat for over an hour. We were the last scheduled departure, and when the plane arrived late, the de-icing crew had gone home. We didn't leave until after midnight.
And we arrived... at 8:45 am, 15 minutes earlier than scheduled.
I slept, so I'm not sure if we hit some massive jet stream, or a black hole, or what, but that was the day that I stopped believing flight times.
Edit: Took this photo[1] waiting outside the hotel for an early check-in.
1: https://megapickles.photo/2017/12/25/reflections-of-edinburg...
If you arrived within 15 minutes of the scheduled time, that sounds like a success? One way or another, the airline gave your flight almost exactly the right amount of padding.
Without a doubt, but it makes me incredibly sceptical of flight times now.
That's what I'm not understanding, what are you skeptical about? At least from this data point, they got the time right!
I suppose "flight time" should technically be defined as "time in the air", but realistically, "time it will take you to get from airport A to airport B" is a much more useful metric to passengers.
I suppose "flight time" should technically be defined as "time in the air", but realistically, "time it will take you to get from airport A to airport B" is a much more useful metric to passengers.
There can be a lot of factors involved in that, though. The amount of aircraft in the sky is really high, and accordingly flight paths are often fairly indirect with inefficient corners involved to make the most highly de-conflicted flight paths possible.
When your plane is extremely delayed, to the point that you're the last flight taking off from your airport (and thus likely a large set of local airports), this makes the likelihood that a huge amount of airspace is more clear around your flight path now than it was for the originally scheduled flight. The updated flight path might be massively more efficient, hit favorable wind conditions, open up different speed options along the way, etc.
Since flight times are dependent on a large amount of conditions that are pretty volatile with respect to time, the original estimate was probably true, but with changing conditions and flexible scheduling, they managed to get you where you were going on time.
So, sure, maybe the 'flight time' isn't true, but it's a pretty clear indication the arrival time is.
When your plane is extremely delayed, to the point that you're the last flight taking off from your airport (and thus likely a large set of local airports), this makes the likelihood that a huge amount of airspace is more clear around your flight path now than it was for the originally scheduled flight. The updated flight path might be massively more efficient, hit favorable wind conditions, open up different speed options along the way, etc.
Since flight times are dependent on a large amount of conditions that are pretty volatile with respect to time, the original estimate was probably true, but with changing conditions and flexible scheduling, they managed to get you where you were going on time.
So, sure, maybe the 'flight time' isn't true, but it's a pretty clear indication the arrival time is.
[deleted]
> If a plane takes less time to fly somewhere some of the time because of weather, timely takeoff from departure airport, landing slot availability at the arrival airport or whatever, I don't really care. If they arrive late however, that can be a huge problem, particularly for making connections.
This is exactly how developers need to think about how they communicate schedules to management. Missing an agreed upon date is usually a much bigger deal than pushing the agreed upon date out from the get go.
This is exactly how developers need to think about how they communicate schedules to management. Missing an agreed upon date is usually a much bigger deal than pushing the agreed upon date out from the get go.
> As for CO2, the plane flying slower is more fuel-efficient. Isn't this lower CO2 emissions?
Possibly lower emissions per minute, but if they are in the air for significantly longer, then that may be cancelled out by the extra time.
Often, although fuel efficiency drops off sharply as you go above a certain speed in a vehicle, going slower than that speed is not significantly more efficient per minute, and can therefore be less efficient per distance.
Driving a car for 100 miles at 30MPH is typically less efficient than doing so at 60MPH. Driving that distance at 90MPH is even less efficient.
Possibly lower emissions per minute, but if they are in the air for significantly longer, then that may be cancelled out by the extra time.
Often, although fuel efficiency drops off sharply as you go above a certain speed in a vehicle, going slower than that speed is not significantly more efficient per minute, and can therefore be less efficient per distance.
Driving a car for 100 miles at 30MPH is typically less efficient than doing so at 60MPH. Driving that distance at 90MPH is even less efficient.
Think of it this way: if you need to drive from Kansas City to Boise the distance is constant (barring route changes). If you drive at 120mph vs 60mph you will get their faster but you will also use a lot more fuel in total even though when you're going slower you're on the road for twice as long.
Fuel expenditure falls in to two buckets:
1. Moving the vehicle. Accelerating to cruising speed and fighting the deceleration of friction and air resistance.
2. Keeping the vehicle running. Lights, climate control, that sort of thing.
My guess would be that the vast majority of fuel usage for planes is (1) not (2). As evidence of this, airlines care deeply about costs. It's not a high margin business (any more). My argument is that if it wasn't overall more fuel efficient to fly slower airlines just wouldn't do it. More evidence, the latest planes (A350, B787) have a lower cruising speed than, say, the 747. This also wouldn't be the case (IMHO) if it didn't decrease fuel costs.
Fuel expenditure falls in to two buckets:
1. Moving the vehicle. Accelerating to cruising speed and fighting the deceleration of friction and air resistance.
2. Keeping the vehicle running. Lights, climate control, that sort of thing.
My guess would be that the vast majority of fuel usage for planes is (1) not (2). As evidence of this, airlines care deeply about costs. It's not a high margin business (any more). My argument is that if it wasn't overall more fuel efficient to fly slower airlines just wouldn't do it. More evidence, the latest planes (A350, B787) have a lower cruising speed than, say, the 747. This also wouldn't be the case (IMHO) if it didn't decrease fuel costs.
Isn't there's a 3. for airplanes - the constant force required to keep the plane in the sky? Cars don't have that, and there's going to be a particular speed at which that speed / time ratio changes for a plane compared to a car.
Also, is it necessarily fuel costs behind the decision to steer away from 747, or could it be other costs, like plane utility and capacity, parts and service cost, and the requirements of cross training?
Also, is it necessarily fuel costs behind the decision to steer away from 747, or could it be other costs, like plane utility and capacity, parts and service cost, and the requirements of cross training?
Cars do have that. It shows up as "rolling resistance" in the tires when the vehicle moves, which varies depending on tread depth and inflation pressure. That drops to zero when lateral motion stops, though, and even the worst possible operational configurations won't cost you more than about 3% of your fuel. For boats, greater mass to float means deeper draft, and more resistance on the hull when it is moving. All that gravity-fighting energy is basically nothing for a ground-based vehicle when it is at rest, but manifests as a percentage loss when it moves. You can only escape it with a perfectly rigid, perfectly spherical object, on a perfectly flat surface.
If an aircraft even has the capability to hover in place, it usually has to expend even more fuel to do so than flying an orbit or holding pattern. The ideal way for an aircraft to handle the counter-gravity force is to push an infinite amount of air downward at infinitesimal speed. A helicopter would want to have infinitely long rotor blades, rotating at an imperceptibly slow rate. Obviously, we can't do that, so very long blades spinning slowly enough to see them move is the best compromise we can manage. The output of a jet engine is a relatively small amount of air, moving very fast, but the jets push the craft though the atmosphere, and the wings translate that forward motion into pushing a larger amount of air downward just a little bit, for more efficient lift. Vectoring the engine thrust downward to hover in place means you lose that efficiency boost from the wings. Also, rotary-wing aircraft that are heavily-laden experience "coning", which reduces hover efficiency by making the force from each wing slightly off vertical, and some of the lifting energy goes into canceling out a lateral wobble.
Keeping a plane in the air for another 15 minutes of fighting gravity just isn't significant compared to the effects from changing its speed away from the aircraft's efficiency optimum in order to arrive 15 minutes later, or from fighting air resistance by doing a holding pattern at optimal speed and altitude for enough extra distance to expend another 15 minutes. As long as the flaps are not extended, the plane is just not very concerned with gravity.
Also, once you hit about 11 km/s, you don't need to expend any more energy on counteracting gravity, anyway. At that point, it's all about atmospheric drag.
If an aircraft even has the capability to hover in place, it usually has to expend even more fuel to do so than flying an orbit or holding pattern. The ideal way for an aircraft to handle the counter-gravity force is to push an infinite amount of air downward at infinitesimal speed. A helicopter would want to have infinitely long rotor blades, rotating at an imperceptibly slow rate. Obviously, we can't do that, so very long blades spinning slowly enough to see them move is the best compromise we can manage. The output of a jet engine is a relatively small amount of air, moving very fast, but the jets push the craft though the atmosphere, and the wings translate that forward motion into pushing a larger amount of air downward just a little bit, for more efficient lift. Vectoring the engine thrust downward to hover in place means you lose that efficiency boost from the wings. Also, rotary-wing aircraft that are heavily-laden experience "coning", which reduces hover efficiency by making the force from each wing slightly off vertical, and some of the lifting energy goes into canceling out a lateral wobble.
Keeping a plane in the air for another 15 minutes of fighting gravity just isn't significant compared to the effects from changing its speed away from the aircraft's efficiency optimum in order to arrive 15 minutes later, or from fighting air resistance by doing a holding pattern at optimal speed and altitude for enough extra distance to expend another 15 minutes. As long as the flaps are not extended, the plane is just not very concerned with gravity.
Also, once you hit about 11 km/s, you don't need to expend any more energy on counteracting gravity, anyway. At that point, it's all about atmospheric drag.
"You can only escape it with a perfectly rigid, perfectly spherical object, on a perfectly flat surface."
An approximate description of a train.
An approximate description of a train.
Pretty sure it's a cow.
3. Heat given off by the engine and propulsion mechanism when running at that speed.
For many vehicles, the difference in that factor between running at ideal cruising speed (the 60MPH car in both of our examples) and a lower speed is minimal, and could well be offset or overtaken by the extra spend in (2). This is my 30MPH car example.
Running at a higher than ideal speed is inefficient in this factor and increases fuel usage a lot. This is your 120MPH (my 90MPH) example.
As you say, airlines care deeply about costs. It is highly unlikely that they were mostly running their planes inefficiently above design cruise speed, and are now slowing down to at or below the design cruise speed. It is more likely that they have always been at around the optimal speed, and are now going slower than that to reduce the risk of fines.
For many vehicles, the difference in that factor between running at ideal cruising speed (the 60MPH car in both of our examples) and a lower speed is minimal, and could well be offset or overtaken by the extra spend in (2). This is my 30MPH car example.
Running at a higher than ideal speed is inefficient in this factor and increases fuel usage a lot. This is your 120MPH (my 90MPH) example.
As you say, airlines care deeply about costs. It is highly unlikely that they were mostly running their planes inefficiently above design cruise speed, and are now slowing down to at or below the design cruise speed. It is more likely that they have always been at around the optimal speed, and are now going slower than that to reduce the risk of fines.
Totally agree. No strong reason how CO2 emissions are affected by padding - yes IF there is additional time circling in the air, but then the airline is rarely solely responsible and a clear financial incentive exists.
Note that the bottom half of the article is a sales pitch for his business flow product!
Note that the bottom half of the article is a sales pitch for his business flow product!
> No strong reason how CO2 emissions are affected by padding
Quite often airliners arriving at my local airport ask ATC for a dogleg course for 'additional track miles' on approach to pad their arrival time or burn-off fuel.
It's purely a request by the pilots, not a traffic issue. CO2 being traded directly for convenience.
Quite often airliners arriving at my local airport ask ATC for a dogleg course for 'additional track miles' on approach to pad their arrival time or burn-off fuel.
It's purely a request by the pilots, not a traffic issue. CO2 being traded directly for convenience.
Requesting additional track miles could be because the aircraft wasn't yet configured for landing, perhaps because ATC held the aircraft high due to traffic, or because the pilots didn't manage the decent well.
There are also maximum landing weights (which are different from max takeoff weights) which could potentially be a factor.
There are also maximum landing weights (which are different from max takeoff weights) which could potentially be a factor.
That doesn't seem to be related to padding. Airlines still like to arrive early. If there's no gate available, it's cheaper for the airline to wait on a taxiway than to circle in the air. Fuel costs are a major driver of airline profitability, hence airlines have no incentive to spend time in the air if it's not absolutely necessary.
[deleted]
While flying sucks. In recent years I felt like I've been able to make connections way easier than in the past.
It used to be any two flights even remotely close to landing and departing time and I was really hesitant to book them .... less so now.
It used to be any two flights even remotely close to landing and departing time and I was really hesitant to book them .... less so now.
>I also question the suggestions that longer published flight times mean more CO2 and there's no incentive for airlines to become more efficient.
>Just the other day I flew out of NYC and it took us 40+ minutes of being in a queue to take off behind 15-20 other planes because reasons.
That anecdote is exactly why the claim that there is no incentive for airlines to increase efficiency is so bogus. The vast majority of scheduling delays occur because of on-the-ground and ATC issues that are the sole responsibility of the airports involved. An airline can't do much to combat the inefficiencies that result from a notoriously incompetent airport and their inability to properly manage traffic so gates clear on time.
>Just the other day I flew out of NYC and it took us 40+ minutes of being in a queue to take off behind 15-20 other planes because reasons.
That anecdote is exactly why the claim that there is no incentive for airlines to increase efficiency is so bogus. The vast majority of scheduling delays occur because of on-the-ground and ATC issues that are the sole responsibility of the airports involved. An airline can't do much to combat the inefficiencies that result from a notoriously incompetent airport and their inability to properly manage traffic so gates clear on time.
> As for CO2 [...] 40+ minutes of being in a queue to take off
Guess what the engines are doing at this time. Even worse if they tell planes to circle before landing because there are too many landings at this time.
Guess what the engines are doing at this time. Even worse if they tell planes to circle before landing because there are too many landings at this time.
I once wondered why aircraft don't have electric motors (either battery or APU powered) to move them to the holding point at which point the fire up the engines. Turns out Airbus has a patent on it, it's not yet being used due to complexity / weight tradeoffs.
There was this other start up which planned to use AGV to tow the planes till the take off point. Would be much simpler than trying to modify the plane itself.
https://en.m.wikipedia.org/wiki/TaxiBot
https://en.m.wikipedia.org/wiki/TaxiBot
I would agree with this predictability point, except that they still find ways to undermine predictability down the line.
For example, the latest thing American Airlines seems to be doing is changing schedules in radical ways between time of purchase and day of travel. The last three itineraries I've had on American, I've gotten an e-mail weeks after buying the ticket saying that one of my flights now had a schedule several hours after the originally booked and ticketed flight. What then, predictability?
For example, the latest thing American Airlines seems to be doing is changing schedules in radical ways between time of purchase and day of travel. The last three itineraries I've had on American, I've gotten an e-mail weeks after buying the ticket saying that one of my flights now had a schedule several hours after the originally booked and ticketed flight. What then, predictability?
So I fly AA a lot because of Oneworld basically so I'm familiar with their faults.
If this is recent however it's not entirely their fault. AA is a big customer for the 737 MAX. That plane's grounding has hit their schedule pretty hard. Most of those flights involved Miami for some reason but to backfill those routes they've taken planes off existing routes that weren't fully utilized. Like I'm fairly sure some weekend JFK-SEA flights were canceled and my guess was to free up an old 737 for some other route.
They're also the largest airline in the world I believe so i can't even begin to imagine the complexity of the logistics of this like making sure you have a flight crew in the right place as well as all the other changes to services like maintaining the plane, cleaning it after a flight, baggage handling, stocking the plane with food and drinks and so on.
If your changes in itinerary were less recent than that then my next question is does this involve regional flights? I fly between hubs mostly so I haven't had that experience.
If this is recent however it's not entirely their fault. AA is a big customer for the 737 MAX. That plane's grounding has hit their schedule pretty hard. Most of those flights involved Miami for some reason but to backfill those routes they've taken planes off existing routes that weren't fully utilized. Like I'm fairly sure some weekend JFK-SEA flights were canceled and my guess was to free up an old 737 for some other route.
They're also the largest airline in the world I believe so i can't even begin to imagine the complexity of the logistics of this like making sure you have a flight crew in the right place as well as all the other changes to services like maintaining the plane, cleaning it after a flight, baggage handling, stocking the plane with food and drinks and so on.
If your changes in itinerary were less recent than that then my next question is does this involve regional flights? I fly between hubs mostly so I haven't had that experience.
Huh, ok, that seems fair. I was wondering if the 737 max was involved, but didn't realize the ripple effects were that big. I've had schedule changes from them in the last month or so all up and down the NE corridor mostly.
American has 24 Boeing 737-MAX8 planes out of a fleet of 963. For comparison, Southwest, who also has a large fleet of planes, has 34 out of 754.
Effectively they are operating a fleet that is 2.5% smaller than normal. I expect some impact to their schedule, but it shouldn't hit it that hard.
Effectively they are operating a fleet that is 2.5% smaller than normal. I expect some impact to their schedule, but it shouldn't hit it that hard.
2.5% may seem small but I'd wager the ripple is larger than you think. I have read upwards of 90 regularly scheduled flights being canceled well into June. Assume each flight has an average of 150 passengers (plane capacity is between 138-230) then you are looking at 13,500 lost connections every day, seven days a week well into high time for travel. I am hard pressed to believe that sacrifices will not be made on account of this seemingly minimal fleet size change.
> As for CO2, the plane flying slower is more fuel-efficient. Isn't this lower CO2 emissions?
It is not only about fuel. Right? Article is talking about punctuality. People will use competitors if an airline is not on-time. So with padding they create a safety gap to make sure they arrive on-time.
I believe 15mins safety gap is fair as it is extremely difficult and expensive to always operate on-time without a major airport redesign and technological advancement in how the system works. It gives passengers a reliable arrival time to plan whatever they have next.
It is not only about fuel. Right? Article is talking about punctuality. People will use competitors if an airline is not on-time. So with padding they create a safety gap to make sure they arrive on-time.
I believe 15mins safety gap is fair as it is extremely difficult and expensive to always operate on-time without a major airport redesign and technological advancement in how the system works. It gives passengers a reliable arrival time to plan whatever they have next.
[deleted]
Except that in certain areas (e.g. US domestic flights) most/all airlines reduce average flight speed on purpose to save fuel, knowing that no other airline will compete with them. This is precisely what a functioning Antitrust should fight.
I think other public-interest agencies, besides antitrust-enforcement, might not want airline competition to be based on "who's willing to burn the most jet fuel to shave a few minutes off business travel".
i agree. with fuel prices so high and airlines being so conscious of them, i would imagine they're making every last bit of effort to conserve fuel. The incentives all seem to be correct.
The leading "What airlines don't want you to know" tone of this post is probably to manipulate the reader into reading the whole article, so you can find out what "they don't want you to know", which never really comes.
The leading "What airlines don't want you to know" tone of this post is probably to manipulate the reader into reading the whole article, so you can find out what "they don't want you to know", which never really comes.
NYC has always been subject to long delays... it’s a major pita.
This is a surprisingly poor article from the BBC.
So, padding, according to this article has a negative environmental impact. But that argument isn't justified and doesn't make sense, most time lost is either unavoidable for the airline (e.g. airport problems/weather) or at a phase of travel without the engines running (boarding delays, waiting for a gate, etc).
Flying slower is actually a environmental win since aircraft are more efficient at slower speeds (although costs more to the airline due to staffing/opportunity cost).
They seem to want us to believe that if padding was removed, and airlines magically got more efficient, that they'd use less fuel but what is the mechanism? What phase of flight sees the fuel reductions? It is like they don't know that aircraft often use either ground-power or only the generator while waiting.
In fact the core premise of the article is clickbait. Oh no, airlines are making sure you can plan your travel times accurately by accounting for common delays within a route! The horror! Sorry, but not biting today.
So, padding, according to this article has a negative environmental impact. But that argument isn't justified and doesn't make sense, most time lost is either unavoidable for the airline (e.g. airport problems/weather) or at a phase of travel without the engines running (boarding delays, waiting for a gate, etc).
Flying slower is actually a environmental win since aircraft are more efficient at slower speeds (although costs more to the airline due to staffing/opportunity cost).
They seem to want us to believe that if padding was removed, and airlines magically got more efficient, that they'd use less fuel but what is the mechanism? What phase of flight sees the fuel reductions? It is like they don't know that aircraft often use either ground-power or only the generator while waiting.
In fact the core premise of the article is clickbait. Oh no, airlines are making sure you can plan your travel times accurately by accounting for common delays within a route! The horror! Sorry, but not biting today.
> This is a surprisingly poor article from the BBC.
It's not a staff writer. I always check these things once I started to realise that some of the biases I saw in news reporting were actually determined actions by a relatively small number of independent writers.
Here's her bio on Forbes: https://www.forbes.com/sites/kathryncreedy/#4c0ca61271e2 (though she's an independent writer as far as I can tell).
In my experience the BBC buys up a fair amount of stuff to just "fill up" the offering. Usually it's pretty poor quality. I don't actually have an opinion on this piece since I know nothing of the subject. I just want to encourage people to understand where their "news" comes from.
It's not a staff writer. I always check these things once I started to realise that some of the biases I saw in news reporting were actually determined actions by a relatively small number of independent writers.
Here's her bio on Forbes: https://www.forbes.com/sites/kathryncreedy/#4c0ca61271e2 (though she's an independent writer as far as I can tell).
In my experience the BBC buys up a fair amount of stuff to just "fill up" the offering. Usually it's pretty poor quality. I don't actually have an opinion on this piece since I know nothing of the subject. I just want to encourage people to understand where their "news" comes from.
It's not just flying slower. If you've ever flown into London, you are probably familiar with the notion of a holding pattern. When things get busy at the airport, due to poor scheduling, it is quite common for planes to fly in circles for 10-20 minutes or even longer in some cases.
Also, planes sitting on taxi lanes burning fuel with six planes in front of them is a common issue. Planes are assigned landing and take off slots and if they miss those, that's a problem.
So, if the schedule is unrealistic, planes might be taking off "on time" knowing full well they'll be circling downtown London for some time.
Also, planes sitting on taxi lanes burning fuel with six planes in front of them is a common issue. Planes are assigned landing and take off slots and if they miss those, that's a problem.
So, if the schedule is unrealistic, planes might be taking off "on time" knowing full well they'll be circling downtown London for some time.
It's not poor scheduling, so much as Heathrow being at 99.5% capacity which means queuing is required so they can maintain one landing per minute.
Yeah, the airport is at capacity. I'm not seeing how it has anything to do with schedule padding at all. They're doing take-offs and landings there as quickly as possible.
Airlines know before they take off their ETA to the other side pretty much down to the minute. Their planning builds in padding so that they are guaranteed to make it on time. Which means they expect to arrive early and end up in a holding pattern because the take off slot and landing slot are deliberately misaligned. This is exactly what the article is implying.
That's of course aside from the inevitable issues arising from operating at 99% capacity. Anyone familiar with queuing theory or logistics knows that this just means things pile up at the cost of delays and extra fuel being burnt. So, that too is poor planning. You never operate systems with queues at close to 100% capacity unless you are looking for severe cost overruns and bottlenecks.
This poor planning results from misaligned incentives. Airports can just park planes in holding patterns for however long they desire. It's not their fuel being burnt. So they over provision knowing full well they will have planes in holding patterns throughout the day, This maximizes their revenue. So they are actively incentivized to do this. Likewise, airlines buy fuel cheaply and only get penalized for being late. So they are incentivized to implement padding.
So, the fix is re-aligning the incentives for airports and airlines to minimize planes in holding patterns and fuel being burnt. There are several ways to do this but the bottom line would be making sure both airlines and airports aim to not have planes in holding patterns because that costs both of them something.
That's of course aside from the inevitable issues arising from operating at 99% capacity. Anyone familiar with queuing theory or logistics knows that this just means things pile up at the cost of delays and extra fuel being burnt. So, that too is poor planning. You never operate systems with queues at close to 100% capacity unless you are looking for severe cost overruns and bottlenecks.
This poor planning results from misaligned incentives. Airports can just park planes in holding patterns for however long they desire. It's not their fuel being burnt. So they over provision knowing full well they will have planes in holding patterns throughout the day, This maximizes their revenue. So they are actively incentivized to do this. Likewise, airlines buy fuel cheaply and only get penalized for being late. So they are incentivized to implement padding.
So, the fix is re-aligning the incentives for airports and airlines to minimize planes in holding patterns and fuel being burnt. There are several ways to do this but the bottom line would be making sure both airlines and airports aim to not have planes in holding patterns because that costs both of them something.
> Also, planes sitting on taxi lanes burning fuel with six planes in front of them is a common issue.
They hardly burn any fuel when they are waiting in the lane. The real consumption occurs when they get airborne.
They hardly burn any fuel when they are waiting in the lane. The real consumption occurs when they get airborne.
I googled it and the quote "In a 15-minute taxi between gate and runway, a Boeing 747 can burn about a tonne of fuel." seems to pop up a lot. So not exactly nothing. So, reducing the average span off time between engine start and take off could quite literally save tonnes of fuel.
Of course they consume more after they take off and in holding patterns. But sounds like there's some gains to be made here.
Of course they consume more after they take off and in holding patterns. But sounds like there's some gains to be made here.
Its not like the taxi time will be reduced to zero. Planes still need to cover the distance to the runway. So what kind of efficiencies are we talking about here?
>Flying slower is actually a environmental win since aircraft are more efficient at slower speeds
Do you have any more information on this? Obviously slower-speed turboprop planes are much more efficient than jet powered planes, but I've read in the past that flying a jet engine slower can actually increase fuel consumption and increase emissions.
Do you have any more information on this? Obviously slower-speed turboprop planes are much more efficient than jet powered planes, but I've read in the past that flying a jet engine slower can actually increase fuel consumption and increase emissions.
There is an efficiency curve for jet transports. There is a defined MRC (max range cruise, which varies by weight) and a calculated LRC (long range cruise, typically defined as 1% less fuel efficient [in kg/nm], which gives 99% of efficiency and about 104% of cruise speed vs MRC).
Modern flight management systems have economy calculators that can predict not only fuel-at-destination figures, but can incorporate winds and other airline cost indices (crew, maint reserves, etc) to emit an "ECON" speed target.
It is only speeds below the MRC that cause a decrease in (still-air) fuel efficiency. Airlines do not typically operate in that speed range in cruise absent an ATC directive to slow down to avoid holding ahead. (Obviously, flying a hold is done below MRC as well.)
Modern flight management systems have economy calculators that can predict not only fuel-at-destination figures, but can incorporate winds and other airline cost indices (crew, maint reserves, etc) to emit an "ECON" speed target.
It is only speeds below the MRC that cause a decrease in (still-air) fuel efficiency. Airlines do not typically operate in that speed range in cruise absent an ATC directive to slow down to avoid holding ahead. (Obviously, flying a hold is done below MRC as well.)
There are two optimal values for speed depending on the objective. There is a max endurance speed (for holding, etc.) and a max range speed, both are a function of altitude.
So slowing down under those speeds will decrease efficiency, but typically the airline's cost index (~additional hourly cost to operate, like crew cost) will typically push the speeds higher to minimize the overall cost.
http://www.eaa1000.av.org/technicl/perfspds/perfspds.htm is about the best thing I can google right now as a reference.
So slowing down under those speeds will decrease efficiency, but typically the airline's cost index (~additional hourly cost to operate, like crew cost) will typically push the speeds higher to minimize the overall cost.
http://www.eaa1000.av.org/technicl/perfspds/perfspds.htm is about the best thing I can google right now as a reference.
> In fact the core premise of the article is clickbait
I feel like basically all the BBC articles I've seen posted here recently are nothing more than clickbait. Does anyone else feel the same?
I feel like basically all the BBC articles I've seen posted here recently are nothing more than clickbait. Does anyone else feel the same?
TBH it feels like all of BBC news has been turning tabloid for the past 5 years or so - many articles feel click- baity and sensationalist.
It's not just written media either - I hear Radio 1 news sections from time to time in the car, and they are so basic and devoid of information it's like they're designed for young children.
It's not just written media either - I hear Radio 1 news sections from time to time in the car, and they are so basic and devoid of information it's like they're designed for young children.
They are no more clickbait-y compared to some articles from other red tops, which appear regularly in the Apple News feed, for example.
Additionally, airlines might choose a more economic route which might take longer but save fuel due to better weather conditions/jet stream.
I agree. The first figure presented out of context is the difference in flight time from the 1960s to today. While some of that is certainly padding, airlines in the 60s actually ran faster.
https://www.youtube.com/watch?v=CHw3nRjj5xc
https://www.youtube.com/watch?v=CHw3nRjj5xc
The title is misleading, it should be: "Why airlines are allocating and publishing longer flight times than are actually needed to fly a certain distance"
And the answer: Because 40% of flights used to be late, now it's only 15%, reducing the amount of compensation airlines have to pay out.
Moving the goalposts. The article tries to make it look like a bad thing, like they're skirting their responsibilities (avoiding payouts), not improving their efficiency and punctuality (which is down to late passengers, which they either have to wait for or have to remove their luggage for, OR other factors outside the airlines' control), and that it's bad for the environment. But what if, and this may sound totally wild here, what if the schedules were too tight to begin with and they've just been adjusted to compensate?
I mean yes, the article makes mention that thanks to padding, a lot of flights seem to arrive early. But is that a bad thing? It means there's a lot more space to play around in. And planes can fly a bit slower, or fly at whatever speed they are most efficient at, instead of having to rush.
Moving the goalposts. The article tries to make it look like a bad thing, like they're skirting their responsibilities (avoiding payouts), not improving their efficiency and punctuality (which is down to late passengers, which they either have to wait for or have to remove their luggage for, OR other factors outside the airlines' control), and that it's bad for the environment. But what if, and this may sound totally wild here, what if the schedules were too tight to begin with and they've just been adjusted to compensate?
I mean yes, the article makes mention that thanks to padding, a lot of flights seem to arrive early. But is that a bad thing? It means there's a lot more space to play around in. And planes can fly a bit slower, or fly at whatever speed they are most efficient at, instead of having to rush.
> reducing the amount of compensation airlines have to pay out.
To be fair though, the point of the compensation is because a delayed flight is _very_ inconvenient. If they're removing that inconvenience by landing at the time they said they would so you can make your plans, then that's completely fine.
To be fair though, the point of the compensation is because a delayed flight is _very_ inconvenient. If they're removing that inconvenience by landing at the time they said they would so you can make your plans, then that's completely fine.
Moving the goalposts.
Or perhaps more properly, re-setting expectations. If you can’t stick to your own schedule, give me one you can stick to. I’m of course reiterating what you already said (“adjusted to compensate”), but from a customer POV I’m going to be less upset if I’m early than if I’m late.
Or perhaps more properly, re-setting expectations. If you can’t stick to your own schedule, give me one you can stick to. I’m of course reiterating what you already said (“adjusted to compensate”), but from a customer POV I’m going to be less upset if I’m early than if I’m late.
>But what if, and this may sound totally wild here, what if the schedules were too tight to begin with and they've just been adjusted to compensate?
In a perfect world this would be solved by having a 90/95/99% percentile arrvial window rather than an arrival time.
In a perfect world this would be solved by having a 90/95/99% percentile arrvial window rather than an arrival time.
You can often get that data if it really matters to you (flightstats sells it, for example), but I’m not sure I want to be running an MCMC analysis every time I book a ticket.
You saved me a click. Thank you!
A simple fix to incentivize more fuel economy is to stop excluding it from fuel taxation, as is still the case in a lot of places. E.g. most EU countries tax fuel for cars, quite heavily, but not for planes. This exemption is starting to look pretty backwards and there is a fair bit of lobbying going on by aviation companies to prevent this from happening.
Low fuel prices currently allow planes to compete with trains for domestic flights in Germany even when the time gained is dubious at best. E.g. Berlin to Munich is a 50-60 minute flight and a 4 hour train journey. However, the train has no checkin and boarding queues and gets you from the downtown area of Berlin to the downtown area of Munich instead two 30-40 minute taxi rides away. If you factor that in, the train starts looking pretty damn good. Flying is still a little faster but so much less convenient.
It might also inform their choices for looking more fuel efficient alternatives. E.g. Berlin-Munich is well in range of the several electrical planes currently under development. IMHO a fleet of hundreds of these could revolutionize domestic flights by allowing cheap, clean flights directly between small city airports that are currently impossible to fly to because of noise and runway length.
Low fuel prices currently allow planes to compete with trains for domestic flights in Germany even when the time gained is dubious at best. E.g. Berlin to Munich is a 50-60 minute flight and a 4 hour train journey. However, the train has no checkin and boarding queues and gets you from the downtown area of Berlin to the downtown area of Munich instead two 30-40 minute taxi rides away. If you factor that in, the train starts looking pretty damn good. Flying is still a little faster but so much less convenient.
It might also inform their choices for looking more fuel efficient alternatives. E.g. Berlin-Munich is well in range of the several electrical planes currently under development. IMHO a fleet of hundreds of these could revolutionize domestic flights by allowing cheap, clean flights directly between small city airports that are currently impossible to fly to because of noise and runway length.
This is dangerous and would increase fuel usage. If the EU taxed jet fuel, airlines would then do several things:
1. They would load up with maximum fuel for inbound flights. Carrying all this extra fuel means they need to burn a bit more fuel for the inbound flight.
2. They would skimp on fuel for outbound flights. This produces a risk of a low-fuel emergency.
3. Many outbound flights would stop just outside the EU for fuel. The additional stop would burn more fuel. Norway, Iceland, Russia, Switzerland, Serbia, Ukraine, and Turkey would all become busy refueling stops.
1. They would load up with maximum fuel for inbound flights. Carrying all this extra fuel means they need to burn a bit more fuel for the inbound flight.
2. They would skimp on fuel for outbound flights. This produces a risk of a low-fuel emergency.
3. Many outbound flights would stop just outside the EU for fuel. The additional stop would burn more fuel. Norway, Iceland, Russia, Switzerland, Serbia, Ukraine, and Turkey would all become busy refueling stops.
That's why we have regulations for how much fuel you must have when you land. So safety is not much of a concern. Many airlines already fly on the limits here by taking off with as little fuel as possible to minimize weight. E.g. Ryan Air and other budget carriers have been disciplined for this. So, this wouldn't be that much of a change. Flying to and from destinations outside the EU burns a lot of fuel and taking off extra heavy means you burn more fuel as well (especially during takeoff, which is when you burn a lot of fuel). So, overall, airlines would be looking to save fuel; not to fly it in unless that would align really well with schedules. For most short haul routes, detours would not make sense and for most long haul routes stop overs don't make much sense either.
> stop excluding it from fuel taxation
Problem for this is that it needs coordination at least on a continent-spanning scale. If the UK decides to tax av fuel but any one of the Netherlands or France or Germany don't, Heathrow stops being a hub airport pretty damn quick, hurting both the economy and the flight options of southern England.
Just like with corporate taxes, countries have an incentive for a race to the bottom, so coordinated action is needed.
Problem for this is that it needs coordination at least on a continent-spanning scale. If the UK decides to tax av fuel but any one of the Netherlands or France or Germany don't, Heathrow stops being a hub airport pretty damn quick, hurting both the economy and the flight options of southern England.
Just like with corporate taxes, countries have an incentive for a race to the bottom, so coordinated action is needed.
>Problem for this is that it needs coordination at least on a continent-spanning scale
Sounds like a job for EU and/or the US federal government.
Sounds like a job for EU and/or the US federal government.
Obviously we need to hold airlines to account to improve their environmental impacts, but I appreciate padding. I know I'm getting fooled, but if it makes sharing ETAs and making peace with a journey, I'd much rather it than be delayed continually.
I think most of us can appreciate the logistical challenges keeping increasingly busy airports running on time, and whilst we need to ensure operational improvements are being made I don't think airlines are deliberately ignoring this (in an age of squeezed profits, being more efficient is the only way to go for them). Padding just makes sense.
I think most of us can appreciate the logistical challenges keeping increasingly busy airports running on time, and whilst we need to ensure operational improvements are being made I don't think airlines are deliberately ignoring this (in an age of squeezed profits, being more efficient is the only way to go for them). Padding just makes sense.
We are not even being fooled. The claim that someone is being fooled when a flight follows its published schedule is nonsense. It is also nonsense to suggest that this somehow removes incentives for airlines to be more efficient, as inefficiency has its costs.
The whole article has the petulant tone of someone having a hissy fit over not getting everything he would like.
The whole article has the petulant tone of someone having a hissy fit over not getting everything he would like.
Exactly; if it was about operational efficiency, then airlines would be able to reduce padding to a minimum, which in turn would allow them to have planes ready to depart much quicker, which will allow them to fly more and thus make more money. I don't get the angle that it's the airlines that don't want to improve their efficiency.
Exactly my feelings. I agree efficiency should be improved, and I would like that total travel time got shorter, but I can accept a small margin to help them adjust if that will give me a consistent arriving time.
This really sounds like a non-issue. As a consumer, I'd much rather have them over estimate the flight schedule and arrive early than the reverse. I live near a smaller regional airport and end up having layovers basically anytime I fly anywhere more than 200 miles away, so I always relax a little easier when I pilot tells me we're landing ahead of schedule on my first leg so I know I wont miss my connection.
As for carbon emissions, I'm guessing that whatever padded on time is spent at the gate isn't really an issue, it's more about drawn out approaches when landing. It seems perfectly reasonable to me that something like this happens when you have so many planes entering and leaving an airport, it's amazing to me that things go as smoothly as they do. Plane travel isn't going anywhere and it seems a little absurd to me that flight time needs to be completely min-maxed down to the minute due to carbon emissions, there are definitely easier and more effective ways to control this.
As for carbon emissions, I'm guessing that whatever padded on time is spent at the gate isn't really an issue, it's more about drawn out approaches when landing. It seems perfectly reasonable to me that something like this happens when you have so many planes entering and leaving an airport, it's amazing to me that things go as smoothly as they do. Plane travel isn't going anywhere and it seems a little absurd to me that flight time needs to be completely min-maxed down to the minute due to carbon emissions, there are definitely easier and more effective ways to control this.
I dont think this article is completely correct, and I dont see padding as a "trick". If the arrival window is more accurate by adding padding to the flight time, then I can plan more effectively when I get to my destination. Aren't airliners also flying slightly slower than they used to in an effort to save fuel(and lower emissions)?
This is actually what any other mode of transportation that uses a schedule has to do: if you have a schedule, you have to take some precautions to ensure you can keep to the schedule most of the time, otherwise you can forget about the schedule. Here in Germany, this is very obvious for bus lines on streets that are usually very busy - they have so much "padding" in their schedule that on less busy days the buses have to travel at 30 km/h instead of 50 km/h to avoid running ahead of schedule.
Here in Canada I've had to sit and wait on the bus while the drive goes into Tim Horton's (coffee shop) because the bus is ahead of schedule.
[deleted]
Huh? This article is ridiculous.
> It’s called “schedule creep”, or padding. And it’s a secret the airlines don’t want you to know about, especially given the spillover effects for the environment.
So… let me get this right… because the announced scheduled arrival time is announced as being an hour later than usual… somehow the plane spends more time in the air and is worse for the environment…
I think the author missed their morning cup of coffee.
> Padding drives higher costs in fuel burn, noise and CO2
Again, with the unsubstantiated and ludicrous claim that an airline giving itself room on the schedule for operational issues not to cause cascading effects somehow means more time in the air, more noise, and more emissions.
I give up. I hope nobody takes this article seriously.
> It’s called “schedule creep”, or padding. And it’s a secret the airlines don’t want you to know about, especially given the spillover effects for the environment.
So… let me get this right… because the announced scheduled arrival time is announced as being an hour later than usual… somehow the plane spends more time in the air and is worse for the environment…
I think the author missed their morning cup of coffee.
> Padding drives higher costs in fuel burn, noise and CO2
Again, with the unsubstantiated and ludicrous claim that an airline giving itself room on the schedule for operational issues not to cause cascading effects somehow means more time in the air, more noise, and more emissions.
I give up. I hope nobody takes this article seriously.
Ok, I'm not the only one. For the most part the gate-to-gate timeline is extremely predictable. They already have the clearances set up and know what route they're flying so the flying bit is not really going to change much outside of unforeseen weather or traffic delays. The variable part is loading, unloading, and staffing issues (someone didn't make it to work) and occasionally absorbing the impact of flight delays.
I suspect the net effect is actually a decrease in CO2 emission because the delay stack at the end of the day doesn't force pilots to bump the throttles a little to cut some time on flights with lots of connections as I've seen them do before.
I suspect the net effect is actually a decrease in CO2 emission because the delay stack at the end of the day doesn't force pilots to bump the throttles a little to cut some time on flights with lots of connections as I've seen them do before.
So this is possible. I fly on JAL all the time for work (internationally). They are pretty much always right on time for all schedule flights. They do things very differently then the US airlines I fly on. They make announcements about boarding time, status etc. more often. They announcements include things like walking time to the gate. There are way more people at the gate organizing the boarding queue and handling the ticket and passport checking then I have seen at other airlines. They have clear signage about which line is for what and walk around with the signs to make sure everyone understands. When you board the aircraft the crew is actively involved in making sure you are able to get in your seat and get your bags put away. If you have a connecting flight with a tight window there are personal at the plane exit waiting for you to help you make the next flight. I have always been impressed by their level of service and detail. I recently had a flight through Tokyo back to the US. As I walk off the plane that just landed and look out the window I can see my bag already off the plane and being put on a cart for transfer. I had a 40 minute window on an international connecting flight through Narita. I would never ever try to schedule that on another airline. I made it with 20 minutes to spare and my bag showed up at my destination just fine. Oh the other amazing thing is that priority tag on your bag for their frequent flyers for making your bag come out first really works, even when landing in SFO or LAX.
I really feel this is a matter of organizational skill and planning. The US airlines just do not care to put in the effort.
https://www.jal.co.jp/en/info/flightstats.html
I really feel this is a matter of organizational skill and planning. The US airlines just do not care to put in the effort.
https://www.jal.co.jp/en/info/flightstats.html
In my experience, fixing ground ops would be the biggest boon to efficiency and customer satisfaction. My experience these days from doing a lot of domestic flying in the U.S. is that lack of ground coordination (takeoff queues, gate availability, randomly sitting on the tarmac for an hour) cost a lot of money and time. If the state of planes in the sky can actively be used to optimize ground ops at airports, I think that'd help consumers and reduce some costs. Other than that, I think consumers could forgive the padding in flight times. If I take off 20 minutes late and still arrive 10 minutes early, I'm happy, so the psychology continues to work.
Problem: "Planes are consistently later than our stated arrival times"
Solution: "Why don't we give more accurate arrival times, so passengers can be more confident in those stated arrival times and minimize disruption to their travel plans"
The Guardian: "This is bad for the environment"
Literally the article is saying that when airlines stopped optimistically lying about arrival time, this somehow poisoned the planet. Despite the fact that both before and after the change being complained about, flights took off at the same real timestamp, spent the same amount of real time in the air, and landed at the same real timestamp.
Solution: "Why don't we give more accurate arrival times, so passengers can be more confident in those stated arrival times and minimize disruption to their travel plans"
The Guardian: "This is bad for the environment"
Literally the article is saying that when airlines stopped optimistically lying about arrival time, this somehow poisoned the planet. Despite the fact that both before and after the change being complained about, flights took off at the same real timestamp, spent the same amount of real time in the air, and landed at the same real timestamp.
HN can be funny. Since this is an article about the airline industry, a lot of people here are criticizing them for setting lower expectations and padding times. And this is an industry that deals with so many environmental, regulatory, administrative and personnel problems completely out of their control.
On the other hand, if it's an article about how "PMs ruin software engineering by pushing for unrealistic deadlines", all of a sudden a job role that depends largely on just people and their (fairly reliable) computers justifies 2x or 3x the time estimates.
On the other hand, if it's an article about how "PMs ruin software engineering by pushing for unrealistic deadlines", all of a sudden a job role that depends largely on just people and their (fairly reliable) computers justifies 2x or 3x the time estimates.
The JAL flights from London to Tokyo and back really annoyed me last year because of padding. The LHR to HND leg arrived 45 minutes early, which meant I had 45 minutes extra of early morning time in Tokyo and 45 minutes less snoozing to try and get ahead of the jetlag.
The return trip was different, if the plane had departed on time it would have reached London at a time when inbound flights are not allowed due to noise restrictions. That meant it was about 2am by the time I was able to board the plane, again not ideal for sleeping.
The return trip was different, if the plane had departed on time it would have reached London at a time when inbound flights are not allowed due to noise restrictions. That meant it was about 2am by the time I was able to board the plane, again not ideal for sleeping.
This is an idiotic article.
First, to suggest that padding comes at the expense of operational improvement is wrong; well-applied padding is operational improvement.
Second, some of those time losses are due to the move from turbojets (which are fast, screamingly loud, and inefficient) to high-bypass turbofans (which are slower, quieter, and much more fuel efficient).
More time is lost as planes usually have to fly complex noise-abatement profiles and navigate more crowded and complex airspaces before they get to cruise.
First, to suggest that padding comes at the expense of operational improvement is wrong; well-applied padding is operational improvement.
Second, some of those time losses are due to the move from turbojets (which are fast, screamingly loud, and inefficient) to high-bypass turbofans (which are slower, quieter, and much more fuel efficient).
More time is lost as planes usually have to fly complex noise-abatement profiles and navigate more crowded and complex airspaces before they get to cruise.
United has a route where the return leg is so short that they make you sit in the plane for an extra hour after you land.
The issue is that they're required to take off from Ben Gurion airport before a certain hour to meet the nighttime curfew / noise abatement requirements. But that has the flight landing in SFO an hour before the customs and immigration desks open, and they're not allowed to open the doors until then.
Wish there was a way to make this particular flight a little longer...
The issue is that they're required to take off from Ben Gurion airport before a certain hour to meet the nighttime curfew / noise abatement requirements. But that has the flight landing in SFO an hour before the customs and immigration desks open, and they're not allowed to open the doors until then.
Wish there was a way to make this particular flight a little longer...
I think the fallacy here is that they can just push back from the gate, trot directly to the runway and takeoff. In any major airport, that's a crapshoot.
I've been spending a lot of time watching ground ops from
http://www.airportviewer.com/airport/KSFO
(courtesy of HN, posted a few months ago). There are times when the planes pile up 14 deep. I saw JFK up to 20 planes on the ground waiting. This is hardly the airlines' fault.
What I dont understand is why they don't use wide-body planes more. I mean, I know the standard explanation: they use too much fuel on short-hauls. But why can't the manufacturer solve this problem, either by reducing the wing size or changing the shape, to have a wide-body, short-to-medium haul aircraft?
Aviation continues to grow, so while I understand the removal of hub-and-spoke, to the distributed pattern, it seems like if there's enough customer demand to run N 737's/A320's per day from SFO to, say, DEN, why not run 0.6*N 777's instead. Or what if southwest slowly replaced their '37 fleet with "short range 777s" ?
Or, more specificially, why don't they enact regulations at some of our busiest airports and say "Sorry, but at peak hours at JFK, you can only arrive/depart wide-body aircraft". Half the planes that run SFO are these tiny skywest embraer and bombardier jets. During peak times, restricting their use and requiring at least a '37 or a320 could boost capacity significantly (+100 people per takeoff/landing)
I've been spending a lot of time watching ground ops from
http://www.airportviewer.com/airport/KSFO
(courtesy of HN, posted a few months ago). There are times when the planes pile up 14 deep. I saw JFK up to 20 planes on the ground waiting. This is hardly the airlines' fault.
What I dont understand is why they don't use wide-body planes more. I mean, I know the standard explanation: they use too much fuel on short-hauls. But why can't the manufacturer solve this problem, either by reducing the wing size or changing the shape, to have a wide-body, short-to-medium haul aircraft?
Aviation continues to grow, so while I understand the removal of hub-and-spoke, to the distributed pattern, it seems like if there's enough customer demand to run N 737's/A320's per day from SFO to, say, DEN, why not run 0.6*N 777's instead. Or what if southwest slowly replaced their '37 fleet with "short range 777s" ?
Or, more specificially, why don't they enact regulations at some of our busiest airports and say "Sorry, but at peak hours at JFK, you can only arrive/depart wide-body aircraft". Half the planes that run SFO are these tiny skywest embraer and bombardier jets. During peak times, restricting their use and requiring at least a '37 or a320 could boost capacity significantly (+100 people per takeoff/landing)
> why don't they enact regulations
Not sure who are "they". FAA only cares about safety. Airport cares about profits. If tiny planes pay the same fee as large ones, why nerf them?
Not sure who are "they". FAA only cares about safety. Airport cares about profits. If tiny planes pay the same fee as large ones, why nerf them?
> FAA only cares about safety
not true. Try flying a cessna into JFK. Apparently ATC just circle you over the atlantic until they "find time to fit you in". private pilot paid his taxes and "has every right to use the facility", but if you actually try it, you'll have a bad time.
not true. Try flying a cessna into JFK. Apparently ATC just circle you over the atlantic until they "find time to fit you in". private pilot paid his taxes and "has every right to use the facility", but if you actually try it, you'll have a bad time.
>Why don't they use wide-body planes more
Off the top of my mind, there are some other non-fuel factors
1- A competitive schedule in a business market includes offering a high number of frequencies, so running several flights on a narrowbody is preferred over a widebody
2- Building off of the above, you can segment your customers better, charging more for business-friendly timing
3- You mention seeing the tiny Skywest regional jets at SFO. While I'm not too familiar with United's route structure, I'd guess that most of these routes may not support a narrowbody (either because of mainline costs or demand)
4- Delta apparently used to run tiny regional jets out of JFK when Jet Blue was starting up in order to squat on slots, but also disrupt operations, since Delta would be much less impacted than Jet Blue.
Off the top of my mind, there are some other non-fuel factors
1- A competitive schedule in a business market includes offering a high number of frequencies, so running several flights on a narrowbody is preferred over a widebody
2- Building off of the above, you can segment your customers better, charging more for business-friendly timing
3- You mention seeing the tiny Skywest regional jets at SFO. While I'm not too familiar with United's route structure, I'd guess that most of these routes may not support a narrowbody (either because of mainline costs or demand)
4- Delta apparently used to run tiny regional jets out of JFK when Jet Blue was starting up in order to squat on slots, but also disrupt operations, since Delta would be much less impacted than Jet Blue.
I think #2 is the strongest case. Wendover Productions talked about that a lot, how you can have 6 different prices for the same flight. #4 is terrible, that's not competition, its warfare. Again Wendover talked about something similar. Icelandair tried going to Dallas, so American immediately began a Dallas route to make their competitor suffer. That may technically be "competition", but the spirit of it is malicious.
I think we should revert to the hub and spoke system. Have huge jets that do nothing but travel between hubs all day. Let the business people have their half, and let the cattle buy essentially last-minute bus-tickets to traverse the country. Then book your ticket from the hub to home. Even though that's inefficient compared to direct routing, a 2 or 3 hour ground delay costs the same (in time) as going from CHI->LAX and then backtracking to phoenix or vegas to your final destination.
Another thing I think could work would be "JIT" routing. where you dont even know where your connections will be, until the day you fly. then you could have sudden, "ad-hoc hubs" that suit that particular day's distribution of travelers. Each morning a huge rack of computers could solve that day's "travelling-salesman problem" of weather, demand, location of aircraft, etc and come up with an optimal solution. people wouldn't like this at first, becuase of fear of the unknown, but I suspect it would lead to monumental increases in efficiency.
I think we should revert to the hub and spoke system. Have huge jets that do nothing but travel between hubs all day. Let the business people have their half, and let the cattle buy essentially last-minute bus-tickets to traverse the country. Then book your ticket from the hub to home. Even though that's inefficient compared to direct routing, a 2 or 3 hour ground delay costs the same (in time) as going from CHI->LAX and then backtracking to phoenix or vegas to your final destination.
Another thing I think could work would be "JIT" routing. where you dont even know where your connections will be, until the day you fly. then you could have sudden, "ad-hoc hubs" that suit that particular day's distribution of travelers. Each morning a huge rack of computers could solve that day's "travelling-salesman problem" of weather, demand, location of aircraft, etc and come up with an optimal solution. people wouldn't like this at first, becuase of fear of the unknown, but I suspect it would lead to monumental increases in efficiency.
How do you propose to have crew available for every possible permutation of that routing? It would take an enormous standing population at every airport in the system, only a small portion of which will work on each given day. Good luck finding employees to take on that arrangement. Routing is about scheduling more than just aircraft.
The crew would be probably the easiest parameter to optimize because they don't have a choice. Let's say the current configuration has a set of crew in PHX and on wednesdays they normally go to denver, 2 hrs away. with a dynamic configuration, they can expect to go on any 2 hour flight or less. the only commitment to the crew is that they are to be returned to their home city on their first day off. If they have enough seniority, then they can be put on the top list of employees to draw from to go to DEN if thats what they want. I don't see the problem. The crew could be routed just as dynamically as the PAX.
Beyond the considerations in this article, I've always found it fascinating that none of the big jets flying today is as fast in routine operation as the first American airliner, the 707. The difference is small, and the reason is partly to do with fuel economy, but it's a very good example of how technology doesn't always go forward in the expected direction.
A similar analogy in computerland is how many of us are doing most of our computing on devices much less powerful than the ones we had ten years ago, a function of switching to mobile devices and high-overhead virtualized computing.
A similar analogy in computerland is how many of us are doing most of our computing on devices much less powerful than the ones we had ten years ago, a function of switching to mobile devices and high-overhead virtualized computing.
also capacity. larger plane need larger wing that enter into transonic regime earlier than smaller wing.
http://www.aerospaceweb.org/question/aerodynamics/area-rule/...
https://en.wikipedia.org/wiki/Drag-divergence_Mach_number
you want to be below or above transonic, and above transonic is banned pretty much anywhere.
http://www.aerospaceweb.org/question/aerodynamics/area-rule/...
https://en.wikipedia.org/wiki/Drag-divergence_Mach_number
you want to be below or above transonic, and above transonic is banned pretty much anywhere.
Is it really true that when flying at less speed you burn more fuel? If air resistance grows quadratically with speed, I would assume that it is not, but there might be another effects on wing efficiency that I ignore...
The drag/speed curve of an airplane is actually U-shaped. Parasitic drag does increase with speed, but induced drag—the drag that results from the production of lift—is highest at slow speeds. The combination of these two curves is a U.
The bottom of the drag curve is the speed at which the airplane will achieve maximum range for a given quantity of fuel; 76% of that speed will achieve maximum endurance. The distinction between range and endurance is that of distance versus time. Max range will get the most distance out of one pound of fuel, while max endurance gets you the most time out of that pound of fuel.
The bottom of the drag curve is the speed at which the airplane will achieve maximum range for a given quantity of fuel; 76% of that speed will achieve maximum endurance. The distinction between range and endurance is that of distance versus time. Max range will get the most distance out of one pound of fuel, while max endurance gets you the most time out of that pound of fuel.
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Here is a pretty good article explaining the optimization between range and speed.
http://code7700.com/aero_range_performance.htm
http://code7700.com/aero_range_performance.htm
Flying faster uses LOTS more fuel per mile travelled. It's not just the aero but also what engines are optimized for
Then Concord wouldn't be dead.
Out of all the scheduling problems the author could have talked about: min connect time, early departures, interline agreements, incidental stops. This has to be one of the more reasonable ones.
Many of the above hint at problems that provide uncertainty and doubt into Travelor itineraries but the discussed topic literally provides more certainty and assists with ensuring less missed connections.
There are some routes and airports that outside of expensive infrastructure cannot handle much more traffic. If you find out you made unreasonable promises you make them reasonable or try and make them possible.
Many of the above hint at problems that provide uncertainty and doubt into Travelor itineraries but the discussed topic literally provides more certainty and assists with ensuring less missed connections.
There are some routes and airports that outside of expensive infrastructure cannot handle much more traffic. If you find out you made unreasonable promises you make them reasonable or try and make them possible.
The article confuses the differing responsibilities of airlines, airports and air services (ATC) who then work together to deliver a realistic schedule.
Airlines are motivated to maximise fleet utilisation so the narrow focus on padding is a misleading and overemphasised element to judge the intent of this specific delay mitigation.
The industry is moving towards increasing collaboration, the article I think avoids mentioning the IATA recommended ACDM approach instead pitching a companies PoC from one of their sources.
Airlines are motivated to maximise fleet utilisation so the narrow focus on padding is a misleading and overemphasised element to judge the intent of this specific delay mitigation.
The industry is moving towards increasing collaboration, the article I think avoids mentioning the IATA recommended ACDM approach instead pitching a companies PoC from one of their sources.
> However, this global trend poses multiple problems: not only does your journey take longer but creating the illusion of punctuality means there’s no pressure on airlines to become more efficient, meaning congestion and carbon emissions will keep rising.
Am I missing something? It's not like flights are spending more time in the air compared to before - it's just that you wait longer and your flight leaves late vs schedule. So how does that increase carbon emissions?
Am I missing something? It's not like flights are spending more time in the air compared to before - it's just that you wait longer and your flight leaves late vs schedule. So how does that increase carbon emissions?
Hard to reconcile the title with this observation: "Part of the problem is schedules are designed by airlines for perfect conditions".
There's a lot of available info for US flight delays at bts.gov
One good example: https://www.bts.gov/topics/airlines-and-airports/understandi...
There's a lot of available info for US flight delays at bts.gov
One good example: https://www.bts.gov/topics/airlines-and-airports/understandi...
This article leaves out air traffic control, which is a major issue. In the US, ATC is a very manual process, and planes get slotted into routes that are more a factor of what the ATC personnel can deal with than anything else.
In most cases, aircraft get lined up in the sky in lanes. If your plane is nice and new and can move efficiently at a higher speed, it doesn't matter because it will get stuck behind an old crappy plane that cannot.
In most cases, aircraft get lined up in the sky in lanes. If your plane is nice and new and can move efficiently at a higher speed, it doesn't matter because it will get stuck behind an old crappy plane that cannot.
The hub and spoke system also contributes to the congestion we see at the airports. A distributed system would be more tolerant to issues like weather, and you can afford to pad flight schedules with little impact on congestion due to the fewer throughput of planes at any one airport. This of course may not make financial sense for the Airline to distribute their operations, would need to be regulated.
We're already starting to see that change. As traffic has grown airlines have added more point-to-point flights that skip the hubs. Newer aircraft have also changed the economics of those route changes well and enabled more point-to-point flights that weren't previously economical.
This article is informative but poorly thought out. Most delays are out of the airlines’ control and generally involve congestion.
Unlike 50 years ago when there was little air traffic and airlines could pick the most direct route, today that is no longer the case. Flights are indeed longer because flying the most direct route or the route with the best tailwinds is no longer possible.
I’m surprised BBC didn’t do more fact checking.
Unlike 50 years ago when there was little air traffic and airlines could pick the most direct route, today that is no longer the case. Flights are indeed longer because flying the most direct route or the route with the best tailwinds is no longer possible.
I’m surprised BBC didn’t do more fact checking.
I didn't understand how this is wasting fuel. Does ATC make them fly slower rather than landing early?
Theoretically a plane may have to sit in a holding pattern if it arrives too early, either due to congestion at the airport or not having a landing slot.
The "wasting fuel" part is some submarine by Baiada that the BBC fell for
Flying slower may actually reduce on emissions.
I've read that the reason why flights have gotten longer is fuel efficiency. Flying slower saves fuel. This was a strategy adopted when fuel prices spiked years ago and it was kept in place because of cost competition.
You shouldn't be downvoted, average cruise speeds now are less than in the 1980s and considerably less than in the 1960s. And modern short / medium haul airliners are designed for lowet cruising speeds.
Ryanair notoriously uses a very aggressive Cost Index for flight planning which favours absolute economy over speed, to the extent that sometimes ATC complains about their low cruising speed
More about CI: https://www.skybrary.aero/index.php/Cost_Index
Ryanair notoriously uses a very aggressive Cost Index for flight planning which favours absolute economy over speed, to the extent that sometimes ATC complains about their low cruising speed
More about CI: https://www.skybrary.aero/index.php/Cost_Index
Finally an explanation. I have been wondering about this.
In my nativity I had always assumed that airline do this to reduce fuel consumption by flying more slowly and hence reducing drag. :)
In my nativity I had always assumed that airline do this to reduce fuel consumption by flying more slowly and hence reducing drag. :)
"Increasing success by lowering expectations" ;-)
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TL;DR:
1) planes fly at a lower speed to save fuel
2) help airlines to claim they have improved on-time (OT) flight performance
3) it makes it easier to swerve the “magical three-hour limit” on delays – the threshold that qualifies passengers to file compensation claims at least under European Union passenger rights’ law.
1) planes fly at a lower speed to save fuel
2) help airlines to claim they have improved on-time (OT) flight performance
3) it makes it easier to swerve the “magical three-hour limit” on delays – the threshold that qualifies passengers to file compensation claims at least under European Union passenger rights’ law.
#3 is a little annoying, especially when the airline is uncommunicative.
It’s natural to assume that an N hour departure delay will cause you to arrive N hours late, and that your connections or other plans will be thrown off accordingly. However, that’s not often true—-schedule padding and changes in flight plans[0] often make up for some of the difference, though they often don’t tell you this until you’re in the air. It would be great if more gate agents could give you an expected departure AND arrival time during delays.
[0] I would not be surprised at all if the airlines explicitly trade off fuel costs vs. the costs of compensation. In other words, if you’re already late, don’t waste fuel try to make up all of the lost time, but use just enough to avoid a compensation-triggering delay.
It’s natural to assume that an N hour departure delay will cause you to arrive N hours late, and that your connections or other plans will be thrown off accordingly. However, that’s not often true—-schedule padding and changes in flight plans[0] often make up for some of the difference, though they often don’t tell you this until you’re in the air. It would be great if more gate agents could give you an expected departure AND arrival time during delays.
[0] I would not be surprised at all if the airlines explicitly trade off fuel costs vs. the costs of compensation. In other words, if you’re already late, don’t waste fuel try to make up all of the lost time, but use just enough to avoid a compensation-triggering delay.
I believe wind speed and direction has a significant effect on flight times - making them inherently unpredictable and risking knock-on effects.
No kidding, an internatial route I take was 8.5 hours 8 years ago and now it is 11.5. I am not sure this is a result of padding or scheduling.
Why don't they just arrive early most of the time? For passengers, being early is as good as "A0".
This article reads like a not-very-well-disguised ad for the methodology that Baiada is selling.
TL;DR: Airlines used to set SLOs that they couldn't hit consistently. They updated the SLOs based on actual performance, and now they hit them much more consistently. Article author seems to believe the pointy-haired boss idea that if they went back to the original (over-optimistic) SLOs then the airlines would somehow increase performance to hit them.
Here the airlines are doing pretty much exactly what I, as a passenger, want, which is to predictably arrive at an airport by a certain time more often. If a plane takes less time to fly somewhere some of the time because of weather, timely takeoff from departure airport, landing slot availability at the arrival airport or whatever, I don't really care. If they arrive late however, that can be a huge problem, particularly for making connections.
As for CO2, the plane flying slower is more fuel-efficient. Isn't this lower CO2 emissions?
40 years ago there were so many fewer planes in the skies. You could fly as fast as you want, take off when you want (pretty much) and land when you want. Well, lack of satellite navigation and tracking mattered but basically the skies were less crowded. Just the other day I flew out of NYC and it took us 40+ minutes of being in a queue to take off behind 15-20 other planes because reasons. You have to have that padding in your schedule.