Major General Henry "Hap" Arnold, Acting Deputy Chief of Staff for Air (becoming Commanding General of the United States Army Air Forces on March 9, 1942), initiated a study with view to develop a glider capable of being towed by aircraft. This directive was set into motion through Classified Technical Instructions (CTI-198 on 24 February 1941, and CTI-203 on 4 March 1941), which authorized the procurement of 2-, 8-, and 15-place gliders and equipment. Eleven companies were invited to participate in the experimental glider program, but only four responded with any interest, Frankfort Sailplane Company (XCG-1, XCG-2), Waco Aircraft Company (XCG-3, XCG-4), St. Louis Aircraft Corp. (XCG-5, XCG-6), and Bowlus Sailplanes (XCG-7, XCG-8). Only Waco Aircraft Company was able to deliver the experimental glider prototypes that satisfied the requirements of Materiel Command, the eight-seat Waco CG-3 (modified to become a production nine-seat glider) and the fifteen-seat Waco CG-4. In October 1941, Lewin B. Barringer was made Glider Specialist, Air Staff, HQ of the Army Air Forces, answering to General Arnold, and placed in charge of the glider program. The shock of the Japanese attack on Pearl Harbor on 7 December 1941 prompted the United States to set the number of glider pilots needed at 1,000 to fly 500 eight-seat gliders and 500 fifteen-seat gliders. The number of pilots required was increased to 6,000 by June 1942. After Barringer was lost at sea on a flight to Africa in January 1943, the program came under direction of Richard C. du Pont. Bigger gliders, such as the 30-troop Waco CG-13A and the 42-troop Laister-Kauffman CG-10A were designed later.