Actually, USNA gets USMC flight spots guarenteed
Look at the statistics...
Recently, the 1047 members of the Class of 2008 chose the following service and warfare specialties to enter after graduation and commissioning:
Naval Aviation: Pilot training -- 224 men and 33 women;
Naval Flight Officer training -- 82 men and 16 women.
Marine Corps Aviation: Pilot training -- 77 men and 6 women;
Flight Officer training -- 2 men.
Surface Warfare: conventional -- 185 men and 66 women;
Nuclear power -- 23 men and 14 women.
Marine Corps Ground: 113 men and 19 women.
Submarine Warfare: 121 men.
Navy Restricted Line and Staff Corps: 8 men and 1 woman, including midshipmen not physically qualified for the unrestricted line duties above, elected specialization in aviation maintenance duty, cryptology, intelligence, supply corps, civil engineering corps and meteorology/oceanography.
Medical Corps: 7 men and 3 women.
Special Warfare (SEAL): 24 men.
Special Operations (diving, salvage and explosive ordnance disposal): 14 men and 1 woman.
Interservice commissioning in the U.S. Air Force: 4 women.
Interservice commissioning in the U.S. Army: 2 women.
Interservice commissioning in the U.S. Coast Guard: 2 men.
It's from
http://www.usna.edu/Admissions/choices.htm