Originally Posted by Cranebill
Enrollment is a SEVIS approved school is only necessary for students enrolling in a full time course of training. Travelers visiting the US from other countries that participate in flight training, but did not come to the US specifically for that purpose are allowed to train less than 18 hours per week.
That is an old wives tail and incorrect - and is often put around by Part 61 Schools who have not completed Part 141 status and therefore are not SEVIS approved for the issue of I-20's.
The ruling states that if you attend the US for a course of study...
The ruling then defines what a course of study is - for vocational training - something that leads to a certification.
Then goes on to say that you cannot undertake that course of study under the visa waiver.
Go look it up. It even cites Flight Training specifically.
I would point you to page 2 first bullet point
http://www.eandvh.com/engine/pubs/ge...spx?id=40&dl=1