1929: THE QUESTION MARK. Through 7 January, to test in-flight refueling and crew and aircraft endurance, Maj Carl A. Spaatz and crew fly the Question Mark, a modified Fokker C2-3 with a Wright 220 HP engine, to a world duration record of 150 hours and 40 minutes. The Question Mark–named for its unknown capacity to remain airborne–was an US Army Air Corps high-wing, trimotor monoplane with a large capacity fuel tank in the cabin, a large hopper in the cabin for receiving fuel, and lines and hand-operated pumps to transfer fuel to the wing tanks. The two modified Douglas C1 biplane tankers each had two 150-gallon cabin tanks and a 40-foot fueling hose. Flying between Santa Monica and San Diego in California, the tankers refueled the Question Mark 43 times, allowing it to remain aloft until engine problems forced a landing. During the refueling, the tankers passed 5,700 gallons of fuel plus oil, food, water, and other items (roughly 40 tons) to the Question Mark. All officers on the Question Mark–Carl Spaatz, Ira Eaker, Harry Halverson, and Pete Quesada–became generals, as did two officers on the refueling aircraft: Ross G. Hoyt and Joseph G. Hopkins. MSgt Roy Hooe, the fifth crewman on the Question Mark, earned a reputation as the best crew chief in the Air Corps. The crew members of the Question Mark were each awarded the Distinguished Flying Cross for the mission, while the refuelers received letters of commendation.