It depends - some agencies you can apply directly without doing a phase 1. Others you need talk to the TPOC of the Phase 1 to find out the process or you have to be invited.
In the current environment - I would contact the TPOC - it could just be stuck in limbo.
SBIRs have been mucked up since last fall. The program lapsed and it just got reauthorized for certain departments. Without that reauth only those who had phase 1's could apply for phase 2's.
We used it for a new Defense/Aerospace projects. Language-wise it's fine although verbose. Intent was to separate similar IP so there was no claim of cross contamination. Built-in threading and a robust standard library is nice.
FWIW - I work in aerospace. I believe this is talking about their FAA Designated Engineering Representatives (DERs). They are employed directly by the company or are consultants - they are subject matter experts in their domain. They act as the FAA delegate within the company. They generally have authority that goes well beyond the typical employee or QA person.
The ones I have worked with have no problem telling management to go pound sand when they are pushing schedule.