IO540, 8 CFR 214.2(m)(9)(iii) is available
here.
Note text in bold as correction to earlier post. Incidenally, "...if the dominant part of the course of study..." answers your query about mixed instruction types.
Originally Posted by 8 CFR 214.2(m)
Students in established vocational or other recognized nonacademic institutions, other than in language training programs
(9) Full course of study. Successful completion of the course of study must lead to the attainment of a specific educational or vocational objective. A full course of study as required by section 101(a)(15)(M)(i) of the
Act means
(iii) Study in a vocational or other nonacademic curriculum, other than in a language training program except as provided in
Sec. 214.3(a)(2)(iv), certified by a designated school official to consist of at least eighteen clock hours of attendance a week if the dominant part of the course of study consists of classroom instruction, or
at least twenty-two clock hours a week if the dominant part of the course of study consists of shop or laboratory work; or
Notwithstanding the core definition of the M visa (located at Sec. 101(15)(M) of INA) requiring a 'full time course of study,'
there is no regulation requiring a flight school candidate who wishs to undertake a part-time course of study (viz, fewer than the hours required above) to obtain a vocational student visa (M-1). There is also no certification regulation requiring schools to offer a full-time course.
Aliens wanting to attend school on a part-time basis can enter the US with a B-1/B-2 visa if their school attendance is 'incidental' to a primary pleasure purpose. See
Special Report from OIG, May 2002.