Pan Am Flight 7
Pan Am Flight 7 was a westbound round-the-world flight operated by Pan American World Airways. On November 8, 1957, the Boeing 377 Stratocruiser 10-29 serving the flight, named Clipper Romance of the Skies, crashed in the Pacific Ocean en route to Honolulu International Airport from San Francisco. The crash killed all 36 passengers and eight crew members.
The flight's fate was not known until about nine hours after its last known radio transmission, by which point the plane would have run out of fuel. No radio reports of any emergencies were received from the flight crew. Under the assumption that the plane could have survived a controlled landing on the ocean surface, the United States Coast Guard launched an extensive search for the plane and any survivors. The week-long hunt became the largest search and rescue operation in the Pacific Ocean up to that date. The bodies of 19 of the victims and pieces of the plane were eventually recovered about northeast of Honolulu.
Investigations into the cause of the crash were inconclusive. Despite theories that the plane may have been the victim of sabotage, poor maintenance, or in-flight fire, investigators could not find enough evidence to support any definite conclusion. The final report from the Civil Aeronautics Board, which conducted the investigation, concluded that the board did not have enough evidence to determine the cause of the accident.
Background
In 1947, Pan American World Airways offered the first regularly scheduled round-the-world flights, westbound from the west coast of the United States, or eastbound from the east coast. The flights stopped in multiple cities over the course of several days before ending the trip on the opposite coast. Passengers on these flights had the option to include extended stopovers in any of the cities along the way until a later flight departed the city. In November 1957, Flight 7 was the flight number assigned to one of the company's westbound round-the-world flights, which departed San Francisco International Airport on Friday morning and included 15 intermediate stops before eventually arriving at Philadelphia International Airport on the following Wednesday.Flight
At 11:30a.m. on November 8, 1957, Flight 7 left San Francisco on the first leg of the trip, to Honolulu International Airport. Flight 7 carried 36 passengers and 8 crew members, and was expected to take ten hours and fifteen minutes. The plane was one of Pan Am's long-range double-decker Boeing 377 Stratocruisers, named Clipper Romance of the Skies. It had enough fuel for approximately thirteen hours of flight, and was loaded to its maximum takeoff weight of. The flight plan called for a cruising altitude of and an airspeed of.At 5:04p.m., the captain made a routine position report while the flight was east of Hawaii. He said the plane was cruising at an altitude of and was encountering headwinds of approximately. He was due to make his next position report at around 6:00p.m., but there were no further communications. At 6:42p.m., Pan Am notified the United States Coast Guard that it had not heard from the plane in more than 90 minutes, which was considered unusual, but not necessarily alarming. After another 90 minutes had passed without word from the flight, the Coast Guard dispatched the first search planes.
Search
Four surface vessels, submarines and, and a number of aircraft from Honolulu conducted the search on the first day. Military authorities were asked to prepare additional planes and ships to join the search at dawn. The searchers were unable to locate the missing flight; authorities held on to the hope that the flight's radio was malfunctioning. To address the possibility that Flight 7's navigation equipment had failed, the Coast Guard ordered all ships at Pearl Harbor to shine their lights into the sky so they could be seen by the flight and used as beacons. A military air transport plane reported spotting lights on the water, which caused a burst of activity, but it was later determined to be only the lights of a ship. At 3:00a.m. on November 9, when all of the fuel aboard the plane would have been consumed, Robert Murray, Pan Am's executive vice president of the Pacific Alaska Division, declared that the plane was presumed to be "down" somewhere over the Pacific Ocean.By the next day, the search party had been expanded to at least 30 aircraft and 14 surface vessels. USS Philippine Sea joined the search from Long Beach, California, with its helicopters and radar-equipped anti-submarine planes. A few hours later, USS John R. Craig and USS Orleck left San Diego to join the search. The Coast Guard enlarged the search area to of the Pacific Ocean east of Hawaii. Pan Am dispatched a sister Stratocruiser from San Francisco, loaded with supplies that it could drop to the ocean surface if needed, and sent a Douglas DC-7 to the search area with enough fuel to stay airborne for 16 hours. The week-long search for the missing plane eventually became the largest search in the Pacific Ocean to that date. Pan Am officials expressed confidence that the craft could stay afloat "almost indefinitely" if it had been forced to land in the ocean and its fuselage had not been punctured.
During the search, three pilots reported that they had heard faint radio distress signals from a hand-operated emergency radio similar to the type that would have been taken aboard life rafts. The signals were heard on the 500 kilohertz distress frequency at the Coast Guard station at ʻUpolu Point on the island of Hawaii. There were ten such broadcasts, over a period of 45 minutes. One pilot reported hearing a series of numbers after the distress signals that he thought ended in the numbers "four four", the last two numbers of the missing aircraft's tail number, N90944. The Coast Guard concluded that the signal was a false alarm and might have come from the mainland or from an unknown party testing their equipment. Pan Am pilots who were personal friends of the lost crew listened to recordings of the radio transmissions and said it was unlikely that the messages had originated from the missing flight. A Pan Am pilot en route between San Francisco and Honolulu also reported seeing a yellow, cylindrical object about, with a dye marker nearby. Three submarines, eight Coast Guard vessels, and five merchant ships converged on the area, but found nothing.
On November 14, the crew of a Navy search plane observed wreckage and bodies in the water, about northeast of Honolulu, and about north of the flight's intended track. One of the victims was still strapped in a seat. A total of 19 victims were pulled from the water; 14 of them were wearing life jackets, and none of them had shoes on, suggesting that the passengers had received some advance warning before the crash. Three of the victims had watches that had stopped at 5:27, 23 minutes after the plane's last radio report. The Navy reported that all of the victims had external injuries and multiple fractures, and concluded that the plane had probably struck the water with tremendous force. The bodies and debris were recovered from a area of the ocean. Rear Admiral T. A. Ahroon, commander of Philippine Sea, reported that there was no evidence that a midair explosion had occurred, but the Navy also found that many of the pieces of debris bore distinct evidence of fire damage. Searchers were unable to recover any of the major components of the airliner; the depth of the ocean in that area was around, which meant that any wreckage on the bottom would be too deep to locate or recover.
Aircraft
The missing aircraft was a Boeing 377 Stratocruiser 10–29 with serial number 15960 and registered with tail number N90944. It first flew on August 30, 1949, as Flagship Ireland for American Overseas Airlines, and was transferred to Pan Am on September 28, 1950, after Pan Am's acquisition of AOA.At the time of the accident, the airframe had accumulated a total of 23,690 logged flying hours. The four engines of the aircraft had total times ranging from 13,459 hours to 16,961 hours, and had been overhauled within the last 1,249 hours of flight. Investigations by the Civil Aeronautics Board found that "the aircraft, engines, and propellers had been maintained as prescribed and were within their time limitations."
The accident was the second worst accident involving the Stratocruiser. The aircraft type had a long history of mechanical problems. Several of the aircraft had experienced runaway propellers, a situation where the pilots were unable to control the pitch of the propellers. In those situations, centrifugal force caused the blades to adjust to the lowest pitch, leading to aerodynamic instability. In 1952, Pan Am Flight 202 crashed in the Amazon basin after its engine and propeller failed in flight. In 1955, Pan Am Flight 845/26 ditched in the Pacific Ocean off the coast of Oregon with four fatalities after one of the aircraft's propellers failed and caused the engine to separate from the wing.
The aircraft assigned to Flight 7 had experienced two incidents shortly before its final flight. On June 18, 1957, it had suffered a runaway propeller as it departed San Francisco. The crew was unable to resolve the situation in the air, turned around, and performed an emergency landing back at the airport. On September 19, 1957, during a flight between San Francisco and Honolulu, the crew heard a loud noise that they described as "similar to dropping the navigation stool on the flight deck". In-flight inspections were performed and the plane landed without incident after the crew found no abnormalities. A Pan Am inspector later investigated and found nothing out of the ordinary, arguing in his report that similar noises could be produced during normal activities.
The aircraft that had been built immediately before the plane assigned to Flight 7 had also crashed the year before. Named the Sovereign of the Skies, with serial number 15959, it was assigned to Pan Am Flight 6. The plane encountered mechanical problems and had ditched in the Pacific Ocean on October 16, 1956, after two of its engines had failed. All 31 people aboard on Flight 6 had been rescued, but the tail broke off on impact and the plane sank only 22 minutes after the forced landing, preventing a detailed investigation into the cause of the engine failures.