Yes, you can.
The school cannot legally issue an I-20 to give you an M1 unless you are enrolled in a course of 18hrs a week or more. That piece of advice came from a TSA inspection at a flying school run by a friend. In reality the abuse of this particular item is actually the opposite to what you are trying to do, ie people apply for an M1 and then work/jump ship.
Yes, you should be honest at the point of entry. Depending on where you fly into , your B1/B2 will allow you to go via one of the automated terminals that print an entry slip that you hand in to the customs guy on the way out.
In reality, having a visa is a good step and definiitely one better than entering under ESTA. A B1/B2 is a respectable visa for short term entry. I have used it myself for just what you describe, with honesty. If you are doing adhoc flight training, have done your TSA, have a visa and already have an airport ID if you are working as cabin crew it is extremely unlikely that you will have any issues. A lot of people will tell you otherwise, but have never done it either.
>No confusion, any pilot training undertaken requires an M1 visa
... is confused. No pilot training requires a visa. People require visas. Pilot training below 12500lbs MTOW requires TSA clearance for three well defined circumstances.
Pilot training for the initial issue of a private ( or cpl if first stand alone faa licence) , multi or instrument rating requires Cat 3 TSA.
You can quite happily add a float or rotary rating to a land certificate for example without TSA.
TSA is not specific about visas, but expects you to be legal/resepctable about your entry.
TSA have in the past asked me to prove that I was legally in the USA when I had to apply for a permission whilst inside the USA, I sent them a copy of my B1/B2 which worked just fine.
Hope that helps
Last edited by custardpsc; 12th Oct 2015 at 15:09.