civilian airman certificate in the grade of private pilot or higher, or Held a lapsed airman certificate, provided that such certificate did not lapse prior to 1 January 1941, or Completed 200 or more previous glider flights, or Previously eliminated from military or naval pilot training, provided at least 50 hours had been logged as principal pilot (solo or performing duties of first-pilot under supervision)and/or as student pilot on military or naval aircraft. Effective 12 June 1942, individuals with no previous flying experience were also accepted into glider training. Individuals meeting the experience criteria listed above were classified as Class A Students, and all others as Class B Students. Several critical changes were introduced into the training program during 1942-43 (as described in the next two paragraphs), however ground training included practical instruction in basic infantry skills in addition to the normal aviation ground school subjects throughout. Glider Pilot Training April 1941 to June 1942 The USAAF's Glider Pilot Training Program was in its embryonic stage. Several experimental courses were conducted during this period, using two-place sailplanes acquired commercially. Extensive use was made of civilian instructors, and of facilities and aircraft at civilian soaring clubs and flight schools. The sailplanes used were optimized for long-duration, unpowered soaring flight however, and did not adequately simulate the flight characteristics of the cargo gliders under development. This resulted in several significant changes to the training program effective 15 June 1942. 15 June 1942 to 13 September 1942 Glider Pilot Training was divided into two principal stages: Preliminary and a combined Elementary-Advanced stage. For Class A students, Preliminary lasted four weeks and included 30 hours of dual and solo training on liaison (L-series) aircraft (e.g.: Piper Cub, various Taylorcraft and Stinson types), with particular emphasis on steep gliding descents, approaches and precision landings without power ("dead-stick" landings). Class B students underwent a somewhat longer Preliminary phase, itself divided into two further phases: Phase I, of five weeks' duration and consisting of 40 hours dual and solo flying on primary trainer (PT-series) or liaison (L-series) aircraft, emphasizing basic aircraft handling, and Phase II, a further two weeks and 15 hours of flight time emphasizing "dead-stick" landings. Training for Class A and Class B students merged at the beginning of the Elementary-Advanced stage, consisting of one week and eight flight hours on two- or three-place training gliders — typically Aeronca TG-5 and similar aircraft — followed