No-boom supersonic flights could slide through US skies soon(theregister.com)
theregister.com
No-boom supersonic flights could slide through US skies soon
https://www.theregister.com/2025/05/17/faa_supersonic_law/
46 comments
> Does that mean you'll see a plane flying overhead, hear the normal drone associated with it, but at one particular moment here a distinctly louder but shorter noise?
Not really. Supersonic means faster than sound. Meaning that the plane flies faster than the sound. Even its own sound. So you would hear nothing before the sonic boom reaches you. Because the sound didn't have time to get to your ears yet.
> I think a supersonic aircraft is constantly "dragging" a boom behind it.
What was really revealing to me is to look at shadowgraph images of supersonic wind tunnel test. Like this one: https://media.sciencephoto.com/image/s3300054/800wm/S3300054...
You can see the dark airplane looking shape. That's the model of the airplane in the wind tunnel. And then you can see that V shaped shadow edge starting from the tip of the nose. That's the sonic boom. It is a sudden step change in pressure. In this visualisation it appears as two lines, but in reality it is a cone centered on the tip of the nose (or other protrusions.)
Where and when your ear crosses that cone surface that's where you experience a sonic boom.
> How do you make the sonic boom go away?
If I understand it correctly their plan is not to make it not happen, but to fly such that the pressure wave is bent upwards away from the ground. Which sounds like a weather dependent trick. I recommend the video in the article which shows the idea.
Not really. Supersonic means faster than sound. Meaning that the plane flies faster than the sound. Even its own sound. So you would hear nothing before the sonic boom reaches you. Because the sound didn't have time to get to your ears yet.
> I think a supersonic aircraft is constantly "dragging" a boom behind it.
What was really revealing to me is to look at shadowgraph images of supersonic wind tunnel test. Like this one: https://media.sciencephoto.com/image/s3300054/800wm/S3300054...
You can see the dark airplane looking shape. That's the model of the airplane in the wind tunnel. And then you can see that V shaped shadow edge starting from the tip of the nose. That's the sonic boom. It is a sudden step change in pressure. In this visualisation it appears as two lines, but in reality it is a cone centered on the tip of the nose (or other protrusions.)
Where and when your ear crosses that cone surface that's where you experience a sonic boom.
> How do you make the sonic boom go away?
If I understand it correctly their plan is not to make it not happen, but to fly such that the pressure wave is bent upwards away from the ground. Which sounds like a weather dependent trick. I recommend the video in the article which shows the idea.
> And is this a real thing that can be done? How do you make the sonic boom go away?
You can't completely make the sonic boom go away, but you can change how it's experienced on the ground through careful design of the airplane shape. The X-59 Quesst (https://en.wikipedia.org/wiki/Lockheed_Martin_X-59_Quesst#De...) is an experimental supersonic aircraft that reportedly reduces the sound of the sonic boom to something comparable to a 'car door closing', mostly by ensuring that different shockwaves created by different parts of the plane don't combine into a single, stronger boom.
> can it be used to make non-supersonic planes quieter, too?
Sadly no; the principles of design are very different for sonic booms and ordinary plane noise. For ordinary aircraft, the big causes of noise are the engines themselves and turbulence over the airframe.
That being said, the problem of ordinary aircraft noise is usually limited to the areas near an airport. Sonic booms are noticed underneath the entire flight path of a supersonic aircraft, even when it's flying at altitude.
You can't completely make the sonic boom go away, but you can change how it's experienced on the ground through careful design of the airplane shape. The X-59 Quesst (https://en.wikipedia.org/wiki/Lockheed_Martin_X-59_Quesst#De...) is an experimental supersonic aircraft that reportedly reduces the sound of the sonic boom to something comparable to a 'car door closing', mostly by ensuring that different shockwaves created by different parts of the plane don't combine into a single, stronger boom.
> can it be used to make non-supersonic planes quieter, too?
Sadly no; the principles of design are very different for sonic booms and ordinary plane noise. For ordinary aircraft, the big causes of noise are the engines themselves and turbulence over the airframe.
That being said, the problem of ordinary aircraft noise is usually limited to the areas near an airport. Sonic booms are noticed underneath the entire flight path of a supersonic aircraft, even when it's flying at altitude.
> How do you make the sonic boom go away?
You can't, but you can prevent it from reaching the ground.
https://www.youtube.com/watch?v=NdJWIkwxjcA
You can't, but you can prevent it from reaching the ground.
https://www.youtube.com/watch?v=NdJWIkwxjcA
The latest generation of supersonic aircraft does still generate a sonic boom, but the key innovation seems to be to fly at an altitude where the sound wave will mostly be reflected.
Source: this picture from the Boom XB-1 website, which was originally made by Pennsylvania State University: https://boomsupersonic.com/wp-content/uploads/2025/02/xb-1-b...
Source: this picture from the Boom XB-1 website, which was originally made by Pennsylvania State University: https://boomsupersonic.com/wp-content/uploads/2025/02/xb-1-b...
https://www.youtube.com/watch?v=r9MzxSfA0R0
So this happens to be rockets. In most plane videos you have sound of other aircraft in the video. This is because people are usually recording at air-shows. It's really hard to find a clean version!
So this happens to be rockets. In most plane videos you have sound of other aircraft in the video. This is because people are usually recording at air-shows. It's really hard to find a clean version!
Because the plane is supersonic, you don’t hear the drone. The first thing you hear is the boom, which is basically the front of the drone which accumulates because the plane is always at the edge of its sound. After the boom, you hear the normal decaying drone as the plane moves away.
growing up i remember experiencing sonic booms a handful of times. i never heard or saw the plane, it would just be the sound and feeling of the boom.
When a boat goes faster than water, it makes water waves. When a plane goes faster than air, it makes air-waves. When a plane goes faster than sound, it makes sound-waves.
It’s lightning/thunder: you will be able to see the plane, and then after a bit, hear the boom. You won’t be able to hear other plane noise, all of the combined noise from turbulence and engines is forced back into the boom.
It is shorter duration, yes, but MUCH louder: F-18s at 5000 feet can rattle windows on the ground! Usually not a good trade-off.
It’s lightning/thunder: you will be able to see the plane, and then after a bit, hear the boom. You won’t be able to hear other plane noise, all of the combined noise from turbulence and engines is forced back into the boom.
It is shorter duration, yes, but MUCH louder: F-18s at 5000 feet can rattle windows on the ground! Usually not a good trade-off.
You're mixing apples and oranges. Air and water are matter, sound is not.
Any sound-producing plane generates sound waves, not just a plane that goes faster than sound.
Any sound-producing plane generates sound waves, not just a plane that goes faster than sound.
Sound is the vibration of matter. Waves do not move matter! Like, look at a leaf on a lake. The leaf moves up and down with the ripples, but does not move back and forth. The water isn’t moving, the wavefront is.
Sonic booms are nothing more than a collapsed wavefront of that wavefront. The speed of sound, definitionally, is the maximal speed at which any physical wavefront can propagate through a medium. (We hear it in air as sound, but no wave can be propagated through the medium any faster than this. You cannot move air any faster than the speed of sound in air.) This causes all of the disturbances from the aircraft moving through the air to be compressed into a single, maximal wave that itself moves at the speed of sound, since it can’t move any faster. Thus the boom.
(You can see a similar cool thing with Cherenkov radiation, where neutrons moving faster than light in water produce a bright blue glow — or, waves of light!)
Sonic booms are nothing more than a collapsed wavefront of that wavefront. The speed of sound, definitionally, is the maximal speed at which any physical wavefront can propagate through a medium. (We hear it in air as sound, but no wave can be propagated through the medium any faster than this. You cannot move air any faster than the speed of sound in air.) This causes all of the disturbances from the aircraft moving through the air to be compressed into a single, maximal wave that itself moves at the speed of sound, since it can’t move any faster. Thus the boom.
(You can see a similar cool thing with Cherenkov radiation, where neutrons moving faster than light in water produce a bright blue glow — or, waves of light!)
I was referring to your explanation "When a plane goes faster than air, it makes air-waves. When a plane goes faster than sound, it makes sound-waves."
In physics, an air wave typically refers to a sound wave. While both of your statements are true (plane makes sound-waves at both speeds), they didn't explain the sonic boom, like you did now.
> You cannot move air any faster than the speed of sound in air.
Minor nitpick, doesn't a plane traveling above Mach 1 displace (i.e. move) air faster than the speed of sound in air? :)
In physics, an air wave typically refers to a sound wave. While both of your statements are true (plane makes sound-waves at both speeds), they didn't explain the sonic boom, like you did now.
> You cannot move air any faster than the speed of sound in air.
Minor nitpick, doesn't a plane traveling above Mach 1 displace (i.e. move) air faster than the speed of sound in air? :)
Right, sorry. The wave can't propagate any faster than the speed of sound -- the air itself be moved faster, but you have to do so by physically displacing it.
> The Supersonic Aviation Modernization Act (SAMA)
> Boom boasts a number of big-name VCs and tech luminaries as funders, including AI poster child Sam Altman
This... can't be a coincidence. Can it?
> Boom boasts a number of big-name VCs and tech luminaries as funders, including AI poster child Sam Altman
This... can't be a coincidence. Can it?
In an article full of marketing speak, NASA only promises a quieter sonic thump:
https://www.nasa.gov/news-release/nasa-lockheed-martin-revea...
"The X-59 is expected to fly at 1.4 times the speed of sound, or 925 mph. Its design, shaping and technologies will allow the aircraft to achieve these speeds while generating a quieter sonic thump."
Further, if the atmospheric conditions aren't right, the cutely named "thump" will turn into a boom again.
I suppose if Qatar gifts Trump the first golden supersonic private jet, it'll also pay fines for "thumps" exceeding the limits.
https://www.nasa.gov/news-release/nasa-lockheed-martin-revea...
"The X-59 is expected to fly at 1.4 times the speed of sound, or 925 mph. Its design, shaping and technologies will allow the aircraft to achieve these speeds while generating a quieter sonic thump."
Further, if the atmospheric conditions aren't right, the cutely named "thump" will turn into a boom again.
I suppose if Qatar gifts Trump the first golden supersonic private jet, it'll also pay fines for "thumps" exceeding the limits.
kgwxd(1)
My immediate thought was of imminent domain destroying houses and running highways through poor neighborhoods. Curious to see which cities/areas you’re allowed to fly the “less noticeable” boom over.
> imminent domain destroying houses and running highways through poor neighborhoods
Nit: eminent not imminent.
Nit: eminent not imminent.
The emissions of supersonic aircraft are insane. They’re just so inefficient. Nobody needs to fly anywhere that fast when they can sleep on a lie flat bed in business class instead. Let’s stop polluting the earth and put that money into battery and hydrogen aircraft instead.
The difference in efficiency between subsonic and supersonic is about 2, which is smaller than the difference between a high density seatIng arrangement and lie-flat density (a factor of 3, I think?). If you’re doing a lie-flat bed, you just eliminated the entire difference in emissions per passenger.
I realize this makes me very unusual and this is probably not a good business idea, but I'd be happy to fly pod-hostel style. I don't mind being stacked as long as I get to lie down.
Me too, but it will never happen due to evacuation issues.
Just don't forget your multipass.
Fuel is the #1 cost of airlines, so this will be niche unless the efficiency problem is solved.
As for climate change and oil use, all aviation globally is only about 7% of oil use and about 3% of carbon emissions. It’s not the main thing to worry about.
Coal fired electricity followed by oil fired land transport (mostly easily electrified cars) are together well over 50% of all emissions and are the easiest things to fix. Deforestation and agricultural emissions are also up there. All of these sources are way easier and cheaper to address than decarbonizing aviation.
As for climate change and oil use, all aviation globally is only about 7% of oil use and about 3% of carbon emissions. It’s not the main thing to worry about.
Coal fired electricity followed by oil fired land transport (mostly easily electrified cars) are together well over 50% of all emissions and are the easiest things to fix. Deforestation and agricultural emissions are also up there. All of these sources are way easier and cheaper to address than decarbonizing aviation.
We can worry about more than one thing at a time
It makes the most sense to tackle the easiest biggest wins first. There is limited attention, money, and political capital. Aviation is perhaps the hardest single thing to decarbonize.
And the biggest consumers of air passenger travel are the rich. They can be incentized to fly less with the stroke of a pen: tax usage. I'm sure the world will keep spinning despite them having only one of two trips to their private island each year.
Thankfully we don't have to stop at one thing. Or even limit ourselves to doing one thing at a time.
Thankfully we don't have to stop at one thing. Or even limit ourselves to doing one thing at a time.
If you want to argue against inequality, make that argument on its own merit without hijacking climate change and using it as a stalking horse.
Climate change is its own problem. Physics doesn’t care what our gini coefficient is. A more equal society that emits too much carbon still has this problem.
A decarbonized society powered by renewable and nuclear energy could still have too much inequality.
Climate change is its own problem. Physics doesn’t care what our gini coefficient is. A more equal society that emits too much carbon still has this problem.
A decarbonized society powered by renewable and nuclear energy could still have too much inequality.
Until democracy is fixed I don't think these problems can be disconnected. But I'll admit that even an equal society could barrel toward its own destruction. I just think equal societies are less likely to, because all our livelihoods would be on the line. None could deny the problem and strong arm the government to ignore it--for the short term benefit of the few at the top.
I think a more equal society would, if it were using fossil fuels, emit more carbon.
A more equals society would have fewer people in poverty. It would have more active services for people who need them. All that represents a lower entropy state. Lower entropy states require more external energy input to maintain, not less.
Allowing vast numbers of people to rot in squalor while a few rich people live it up is a lower energy higher entropy state.
Individual rich people may use crazy amounts of energy but there are not many of them. Bezos’ jet consumes a tiny fraction of the power required to provide continuous modern health care to everyone, for example.
A more equals society would have fewer people in poverty. It would have more active services for people who need them. All that represents a lower entropy state. Lower entropy states require more external energy input to maintain, not less.
Allowing vast numbers of people to rot in squalor while a few rich people live it up is a lower energy higher entropy state.
Individual rich people may use crazy amounts of energy but there are not many of them. Bezos’ jet consumes a tiny fraction of the power required to provide continuous modern health care to everyone, for example.
This assumes that decarbonizing aviation is the only way to address the issue.
A much simpler one, that costs nothing, is simply if we did less aviation. If we had the political will, even just trying to get somewhere close to pricing pollution externalities of aviation (in addition to other pollution sources, to be clear), would immediately reduce demand and make other forms of transportation more competitive.
Of course we don’t have that political will, so it may be true that the only choice is to come up with expensive and esoteric technologies to decarbonize aviation. But I think it’s important to acknowledge that flying less was always an option we (collectively) had, but chose not to take.
A much simpler one, that costs nothing, is simply if we did less aviation. If we had the political will, even just trying to get somewhere close to pricing pollution externalities of aviation (in addition to other pollution sources, to be clear), would immediately reduce demand and make other forms of transportation more competitive.
Of course we don’t have that political will, so it may be true that the only choice is to come up with expensive and esoteric technologies to decarbonize aviation. But I think it’s important to acknowledge that flying less was always an option we (collectively) had, but chose not to take.
True, but why is it that so many people concerned about climate fixate on aviation?
It’s 3% of world carbon emissions. It’s tiny, it’s pivotal to the economy, and it’s hard to change. It’s the worst thing to fixate on, the one you’ll make the least progress toward.
What we should be fixating on is “end coal” because coal burning, largely for power generation, is both the largest single source and one of the easiest to replace. Yet that climate group is called “end oil” not “end coal.” Why?
If we actually think climate change is a problem we need to think like scientists and engineers and prioritize rationally. We also have to be willing to put politics aside and make a broad and wide appeal, arguing that fixing this is in everyone’s long term interest (because it is).
It’s 3% of world carbon emissions. It’s tiny, it’s pivotal to the economy, and it’s hard to change. It’s the worst thing to fixate on, the one you’ll make the least progress toward.
What we should be fixating on is “end coal” because coal burning, largely for power generation, is both the largest single source and one of the easiest to replace. Yet that climate group is called “end oil” not “end coal.” Why?
If we actually think climate change is a problem we need to think like scientists and engineers and prioritize rationally. We also have to be willing to put politics aside and make a broad and wide appeal, arguing that fixing this is in everyone’s long term interest (because it is).
I think part of the answer is that not everyone is convinced it's pivotal.
Only a small amount of aviation is pivotal by any definition, and that portion isn't very price sensitive, so paying for externalities wouldn't make much difference to it.
Even in the richest country in the world, only half of the population took even one plane trip in 2024, and the distribution among those who did, probably skews heavily toward a very small # of frequent fliers.
Aviation is super useful, no doubt. But like many difficult political problems, the benefits are concentrated on those who fly the most, or who consume most of the products that typically fly, and the costs are spread among those who fly the least, or not at all.
Anyway, I have never seen someone advocate to ignore coal in favour of focussing on aviation. But I have seen a lot of people advocate to ignore aviation in favour of focussing on anything but aviation.
As others have said, we can do more than one thing. Some of us can focus on coal, others on aviation. I am just a message board pundit, not involved in coal or aviation, nor advocacy around climate change on either. I am just skeptical of approaches that privilege one pollution source over another. Maybe politics means it's the best we can do, but that's not a very satisfying answer to some of us.
Only a small amount of aviation is pivotal by any definition, and that portion isn't very price sensitive, so paying for externalities wouldn't make much difference to it.
Even in the richest country in the world, only half of the population took even one plane trip in 2024, and the distribution among those who did, probably skews heavily toward a very small # of frequent fliers.
Aviation is super useful, no doubt. But like many difficult political problems, the benefits are concentrated on those who fly the most, or who consume most of the products that typically fly, and the costs are spread among those who fly the least, or not at all.
Anyway, I have never seen someone advocate to ignore coal in favour of focussing on aviation. But I have seen a lot of people advocate to ignore aviation in favour of focussing on anything but aviation.
As others have said, we can do more than one thing. Some of us can focus on coal, others on aviation. I am just a message board pundit, not involved in coal or aviation, nor advocacy around climate change on either. I am just skeptical of approaches that privilege one pollution source over another. Maybe politics means it's the best we can do, but that's not a very satisfying answer to some of us.
I think you're exhibiting a lack of imagination here. There's plenty of time sensitive items the Concorde was used to transport, like organs for transplants, or serum for snake bite victims.
Since the retirement of the Concorde we've regrettably had to use fighter jets for some of these life-saving flights. Sure, rich people subsidized all of it to shave a few hours off their business flights, but given how much avgas Elon's jet uses, it is really more efficient if they half the people who would take a supersonic flight take small private jets instead?
Since the retirement of the Concorde we've regrettably had to use fighter jets for some of these life-saving flights. Sure, rich people subsidized all of it to shave a few hours off their business flights, but given how much avgas Elon's jet uses, it is really more efficient if they half the people who would take a supersonic flight take small private jets instead?
Can you source this at all?
This sounds like it would check out until you realize that the Concorde operated on only two routes, and not on an ad hoc basis.
This is extremely convenient if you happen to need to get some critical medical supply, which happens to not exist in one of these world capitols, from New York to Paris or London and the timing lines up perfectly with a scheduled Concorde flight. How often do organs go transatlantic anyway? Are there tons of snakebite victims in Paris or London that can only be treated by antivenin stored at JFK?
In any other circumstance, you are almost certainly better off sending a medical jet directly from where the item is to where it needs to go. A business jet going straight from where the donor organ is, to where it needs to go is, in almost any circumstance, going to be faster than waiting for the next scheduled flight going supersonic across the Atlantic, then having to transfer to a completely different subsonic plane for the rest of its journey.
This sounds like it would check out until you realize that the Concorde operated on only two routes, and not on an ad hoc basis.
This is extremely convenient if you happen to need to get some critical medical supply, which happens to not exist in one of these world capitols, from New York to Paris or London and the timing lines up perfectly with a scheduled Concorde flight. How often do organs go transatlantic anyway? Are there tons of snakebite victims in Paris or London that can only be treated by antivenin stored at JFK?
In any other circumstance, you are almost certainly better off sending a medical jet directly from where the item is to where it needs to go. A business jet going straight from where the donor organ is, to where it needs to go is, in almost any circumstance, going to be faster than waiting for the next scheduled flight going supersonic across the Atlantic, then having to transfer to a completely different subsonic plane for the rest of its journey.
Source: Concorde exhibit at the Smithsonian, complete with photos of the South Africa flight (which was not its normal route).
Also, the Concorde had other routes. I don't think those routes were even the first ones. I remember reading about Singapore and the Middle East, but according to this website: http://www.concordesst.com/history/destinations.html it even went to Barbados.
It looks like you can learn plenty more by googling or reading newspaper archives.
Also, the Concorde had other routes. I don't think those routes were even the first ones. I remember reading about Singapore and the Middle East, but according to this website: http://www.concordesst.com/history/destinations.html it even went to Barbados.
It looks like you can learn plenty more by googling or reading newspaper archives.
Your source notes that those were charter destinations that were available. It’s really just a list of places that Air France or BA flew. It lists Denver, for example, but I can’t find a single other source that actually shows the Concorde having visited Denver. I’m not arguing that the Concorde only went to NY, London, and Paris. I’m arguing that it was never a critical link in medical supplies logistics, and that using just a little logic explains it.
It mentions nothing about the Concorde being used for medical deliveries on charter, or at all. Nor have you substantiated using fighters for medical deliveries in its lieu, which was asserted. It also notoriously wasn’t viable for longer flights without refueling, which again, is another logistical and timing issue for medical flight.
The rub with Concorde, or any supersonic jet, is that they are not allowed to operate supersonic over land. That makes it an expensive, fuel hogging, very loud, plane with special runway needs.
It mentions nothing about the Concorde being used for medical deliveries on charter, or at all. Nor have you substantiated using fighters for medical deliveries in its lieu, which was asserted. It also notoriously wasn’t viable for longer flights without refueling, which again, is another logistical and timing issue for medical flight.
The rub with Concorde, or any supersonic jet, is that they are not allowed to operate supersonic over land. That makes it an expensive, fuel hogging, very loud, plane with special runway needs.
> given how much avgas Elon's jet uses
Jets don’t consume avgas.
Jets don’t consume avgas.
TIL. I've only made a few business plane trips, but thinking back on it they were all turboprops.
Turboprops also run on jet fuel. Only reciprocating engines use avgas.
Jets will run on anything that burns, most turboprops are allowed to burn avgas in emergencies. Some officially allow 100+ hours of avgas operation between overhauls.
Maybe unpopular opinion but with the costs associated with flying around organs for transplants or serum for snake bites at supersonic speeds, you could save a lot more people in different situations.
They should tax emissions
I now understand that's not the case, but still don't quite know what it is. I think a supersonic aircraft is constantly "dragging" a boom behind it. So when it passes overhead sometime later you'll hear a boom. Is that right? Does that mean you'll see a plane flying overhead, hear the normal drone associated with it, but at one particular moment here a distinctly louder but shorter noise?
And is this a real thing that can be done? How do you make the sonic boom go away? As someone who lives where planes are flying overhead constantly, can it be used to make non-supersonic planes quieter, too?