Don't lump visa and TSA together. They're totally different beasts, managed by two totally different agencies, under totally different legislation, for totally different purposes. The only link between them is that TSA approval may be withheld or withdrawn if you are found to be in the US without a valid immigration status. But what a "valid immigration status" is, is determined by the department of immigration (or whatever it's called) and not by the TSA.
(Heck, if you apply for a visa you will be fingerprinted electronically. But for some obscure reason these electronic fingerprints cannot be used for the TSA process... That's showing how well these two departments work together.)
There may be situations where you need neither, one or both of them.
An M-1 visa is required when your primary purpose of visiting the US is training of some sort. Whether that's for a student exchange program, vocation studies or pilot training doesn't matter. If the training is only incidental to your visit, you would not need an M-1 visa, but another visa (or be admitted under the VWP) for whatever the primary purpose of your visit is.
It is my personal opinion (but I am not a visa specialist or anything) that if A&C goes to the US specifically to get trained on the T6/P51 (or fiddles the crew roster so that his employer schedules him to fly to the US at a specific day and time of his choosing, with an extended stay before the flight home) that his primary purpose for visiting the US would be flight training, so an M-1 visa would be required. On the other hand, if you simply have a standing agreement with the training provider that you can have a go whenever your work happens to take you to the US, then this should be possible on a crew visa.
Another issue is that the M-1 visa can only be sponsored by organizations that are connected to the SEVIS system. Within the flight training establishment, that's limited to Part-141 flight schools (typically the large, integrated training schools). So Part-61 schools (the Mom&Pop outfits) will not be able to help you get an M-1 visa. I honestly have no idea how you would solve this dilemma officially and legally, but I suspect a lot of "primary purpose" training at part-61 schools is done under the VWP.
TSA clearance is specific for flight training, so that the TSA can verify you are not a terrorist or something. Basically what the TSA wants to achieve is a vetting of everybody who attends flight training in the USA (or under the FAA oversight - if you do training for an FAA license in a foreign country this also applies).
The initial legislation surrounding the TSA process simply said that everybody who wanted flight training, needed to be vetted. No exceptions. Later on the TSA relaxed this by making exceptions for certain classes of training. Essentially they now want you to go through the vetting process when
- You do training for the initial issue of an airmens certificate. (E.g. your initial training, whatever and whereever that happens to be, under the FAA system.)
- You do training for a rating that greatly enhances your ability to fly an airliner into a building. (Sounds cruel but that's almost the exact wording that's hidden somewhere in the legislation.) Practically speaking this means an ME or IR rating, or a type rating for aircraft over 12500 lbs.
Since A&C already has an FAA license obtained well before 9/11, will not train for an ME or IR, and will train on aircraft that have an MTOW less than 12500 lbs (although the P51 is only a tad under that number...) it is my opinion that TSA clearance would not be required.
From the TSA website:
Category 3 Clarification - For flight training in the operation of aircraft with a maximum certificated takeoff weight of 12,500 lbs. or less, Candidates must obtain AFSP approval for the following three training events:
Single Engine Land (SEL)
-- Includes initial Airman's Certificate, including a private, recreational, or sport pilot certificate. If a private and/or commercial license is the candidate's initial FAA license, it is considered an initial airman's certificate and is not exempt.
Instrument Rating (IR)
Multi Engine Land (MEL)
Each of these three events requires a separate training request.
All other training events on aircraft with MTOW of 12,500 lbs. or less are exempt from AFSP regulations, including Commercial Pilot License (CPL), Airline Transport Pilot License (ATPL), and Certified Flight Instructor (CFI). These events are exempt only if the candidate holds an FAA stand-alone pilot certificate.
https://www.flightschoolcandidates.g...c§ion=WN#C
But once again, I'm not working for the TSA or the US immigration department, so my advice here is worth exactly what you paid for it...
