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On April 4, 1955, a United Airlines Douglas DC-6 named ''Mainliner Idaho'' crashed shortly after taking off from Long Island MacArthur Airport, in Ronkonkoma, Islip, New York, United States. The flight was operated for the purpose of maintaining the currency of the instrument rating of two of the airline's pilots. Shortly after takeoff and only seconds after climbing through , the plane began banking to the right. It continued to roll through 90 degrees; the nose then dropped suddenly and moments later it struck the ground. All three members of the flight crew were killed upon impact. A subsequent investigation found a simulated engine failure procedure was being conducted, which involved a member of the crew pulling back the throttle lever for engine No. 4 prior to taking off. Investigators found that if the throttle lever was pulled back too far, it would cause the propeller to reverse—a feature designed to slow the aircraft upon landing. Once the landing gear was raised, the crew would have to raise a metal flag in the cockpit to bring the propeller blades back into the correct position, since a safety device prevented electric power from operating the rotating mechanism at the roots of the blades unless the aircraft was on the ground or the flag was manually raised. The Civil Aeronautics Board (CAB) concluded one of the flight crew applied full power to No. 4 engine, thinking this would bring the aircraft out of the increasing bank. Because the blades were reversed and the flag was not raised, that increased the reverse thrust from No. 4 engine, causing the DC-6 to spiral out of control. Since the plane was so close to the ground, the suddenness of the bank and dive meant the flight crew had no chance to recover the aircraft before impact. In the aftermath of the accident, the Civil Aeronautics Administration (CAA) issued an Airworthiness Directive ordering all DC-6 and DC-6B aircraft to be fitted with a manual device which could prevent the inadvertent reversal of the propeller blades. United Airlines also stated they had begun installing reverse thrust indicator lights in the cockpits of their DC-6 aircraft, which would warn pilots when a propeller had reversed. ==History== On April 4, 1955, a United Airlines check captain, Stanley C. Hoyt, age 45, was carrying out instrument rating checks on two of the airline's pilots. Hoyt had been employed by United Airlines since 1937, and had 9,763 flying hours experience, 549 of which were in a DC-6.〔 He was training the two pilots, Henry M. Dozier, age 40, and Vernis H. Webb, age 35,〔 so they would be able to retain an instrument rating qualification, allowing them to fly under instrument flight rules.〔 The aircraft was a Douglas DC-6, registration N37512, serial number 43001. The airframe had flown 22,068 flying hours, and had undergone an inspection 105 hours before the accident. The aircraft was powered by four Pratt & Whitney R2800-CB16 engines, fitted with Hamilton Standard 43E60-317 propellers.〔 The weather on the day of the accident was clear, although there was a strong wind of about hitting the airfield from the southwest, with occasional gusts of wind as fast as .〔Job 2001, p. 45.〕 The aircraft made several circuits, taking off and landing again, before eyewitnesses observed the aircraft standing at the end of the runway and then taking off at about 15:50 Eastern Standard Time.〔〔 〕 Loaded with around , the aircraft was far below its maximum permissible weight and the center of gravity was within the prescribed limits for the model of aircraft.〔〔 Between and down the runway, the aircraft reached take-off speed, lifted off the ground, and began climbing normally as the crew retracted the landing gear. Upon climbing through , the aircraft began banking to the right. The climbing bank continued to increase at a rate which alarmed witnesses, and soon after the aircraft rolled through 90° (at which point the wings were vertical to the ground).〔〔 At a height of around , with all four engines producing take-off thrust, the nose began to fall. Moments later the right wing and nose impacted the ground, causing the fuselage to cartwheel over, before the aircraft came to rest, with the correct side up. It was immediately engulfed in flames. All three members of the flight crew were instantly killed. Although emergency services at Long Island MacArthur promptly responded to the crash, the aircraft was destroyed by the post-crash fire.〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「1955 MacArthur Airport United Airlines crash」の詳細全文を読む スポンサード リンク
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