1971 жылғы Калифорниядағы Pan Am рейсінің апатты ұшысы

1971 aviation accident in California, United States

Pan Am Flight 845 was a scheduled international passenger flight between Los Angeles and Tokyo, with an intermediate stop at San Francisco. The flight was operated by a Boeing 747 registered N747PA and named Clipper America. On July 30, 1971, at 15:29 PDT, while it was taking off from San Francisco International Airport bound for Tokyo, the aircraft struck approach lighting system structures located past the end of the runway; this initial mishap seriously injured two passengers and caused significant physical damage to both the runway structures and the aircraft. The crew continued the takeoff, flew out over the ocean, circled while dumping fuel, and returned to SFO. After coming to a stop, the crew ordered an emergency evacuation, during which 27 passengers were injured exiting the aircraft, eight of whom suffered serious back injuries. The flight crew of Flight 845 consisted of five (a captain, a first officer, a flight engineer, a relief flight engineer, and a relief pilot). The captain was Calvin Y. Dyer, a 57 year old resident of Redwood City, California, a pilot with 27,209 hours of flying experience, 868 of which were on the 747. The first officer was Paul E. Oakes, a 40 year old resident of Reno, Nevada, with 10,568 hours of experience, 595 on the 747. The flight engineer was Winfree Horne, who was 57 years old and from Los Altos, California, and had 23,569 hours of flight experience, 168 of them on the 747. The 34 year old second officer, Wayne E. Sagar, was the relief pilot and had 3,230 hours of flight experience, 456 of them on the 747. The relief flight engineer was Roderic E. Proctor, a 57 year old resident of Palo Alto, California, who had 24,576 flight hours, 236 of them on the 747. On July 29, 1971, Dyer, Oakes, Horne, Sagar and Proctor had spent the whole day off duty and had flown the initial Los Angeles to San Francisco leg of the flight.

Flight 845's crew had planned and calculated its takeoff for runway 28L but discovered only after pushback that this runway had been closed hours earlier for maintenance, and that the first 1000 feet (305 m) of runway 01R, the preferential runway at that time, had also been closed. After consulting with Pan Am flight dispatchers and the control tower, the crew decided to take off from runway 01R, shorter than 28L, with less favorable wind conditions. Runway 01R was about 8500 feet (2591 m) long from its displaced threshold (from which point the takeoff was to start) to the end, which was the available takeoff length for Flight 845. Because of various misunderstandings, the flight crew was erroneously informed that the available takeoff length from the displaced threshold was 9500 feet (2896 m), or 1000 feet (305 m) longer than actually existed. Despite the shorter length, it was later determined that the aircraft could have taken off safely if the proper procedures had been followed. As the crew prepared for takeoff on the shorter runway, it selected 20 degrees of flaps, instead of the originally planned 10 degree setting, but did not recalculate the takeoff reference speeds (V1, Vr and V2), which had been calculated for the lesser flap setting and were thus too high for their actual takeoff configuration. Consequently, the critical speeds were achieved late and the aircraft's takeoff roll was abnormally prolonged. In fact, the first officer called Vr at , instead of the planned , because the end of the runway was "coming up at a very rapid speed."

[[File:Pan Am Flight 845 damage. png|right|thumb|Diagram showing penetration of the Boeing 747's fuselage and tail by Approach Lighting System structures (from NTSB final report). After stopping, the aircraft slowly tilted backwards because the body gear had been ripped off or disabled on takeoff. The aircraft came to rest on its tail with its nose elevated. Until the accident, it was not known that the 747 would tilt backwards without the support of the main body gear.

There were no fatalities among the 218 passengers and crew aboard, but 2 passengers were seriously injured during the impact, and during the subsequent emergency evacuation, 27 more sustained injuries, 2 of them seriously. Rods of angle iron from the ALS structure penetrated the passenger compartment, injuring passengers in seats 47G (near amputation of left leg below the knee) and 48G (severe laceration and crushing of left upper arm). After landing, the aircraft veered off the runway on its damaged landing gear and came to a halt. Evacuation commenced from the front because the evacuation order was not broadcast over the cabin address system (it was erroneously broadcast over the radio), the order being given by one of the flight crew exiting the cockpit and noticing that evacuation had not commenced. During that time, the aircraft settled aft, resting on its tail in a nose up attitude. The four forward slides were unsafe for use because of the greater elevation and high winds. Most passengers evacuated from the rear six slides. Eight passengers using the forward slides sustained serious back injuries and were hospitalised. Other passengers suffered minor injuries such as abrasions and sprains.

The accident was investigated by the National Transportation Safety Board (NTSB), which issued its final report on May 24, 1972. The NTSB found the probable cause of the accident:
the pilot's use of incorrect takeoff reference speeds. This resulted from a series of irregularities involving: (1) the collection and dissemination of airport information; (2) aircraft dispatching; and (3) crew management and discipline; which collectively rendered ineffective the air carrier's operational control system.