Flying Tiger Line Flight 739

Flying Tiger Line Flight 739 was a Lockheed L-1049 Super Constellation propliner chartered by the United States military that disappeared on March 16, 1962 over the Western Pacific Ocean. The aircraft was transporting 93 Army men and 3 South Vietnamese from Travis Air Force Base, California to Saigon, Vietnam. After refueling at Andersen Air Force Base, Guam, the Super Constellation was en route to Clark Air Base in the Philippines when it disappeared. All 107 aboard were declared missing and presumed dead.

The airliner's disappearance prompted one of the largest air and sea searches in the history of the Pacific. Aircraft and surface ships from four branches of the US military searched more than 200000 sqmi during the course of eight days. A civilian tanker observed what appeared to be an in-flight explosion believed to be the missing Super Constellation, though no trace of wreckage or debris was ever recovered. The Civil Aeronautics Board determined that, based on the tanker's observations, Flight 739 probably exploded in-flight, though an exact cause could not be determined without examining the remnants of the aircraft.

To date, this remains the worst aviation accident involving the Lockheed Constellation series.

Flight
The aircraft was a 5-year-old Lockheed L-1049H Super Constellation with a total of 17,224 airframe hours. It carried 11 American civilian crew members and 96 military passengers. The flight was operated by the Flying Tiger Line as Military Air Transport Service (MATS) Charter flight 739.

The Super Constellation carried 93 jungle-trained Army Rangers en route to South Vietnam. Their orders were to relieve soldiers in Saigon who had been training Vietnamese troops to fight Viet Cong guerrillas. Also on board were three members of the Vietnamese military. The flight crew consisted of eleven civilians based out of California, including four women. The pilot was Captain Gregory P. Thomas.

The flight originated from Travis Air Force Base, California, and was destined for Saigon. There were four planned refueling stops: Honolulu, Hawaii; Wake Island; Guam; and Clark Air Base, Philippines. The flight arrived at Guam at 11:14 GMT after being delayed for minor maintenance on engines numbers 1 and 3 at Honolulu, and later at Wake Island. The aircraft departed from Guam at 12:57 GMT with an estimated time of arrival at the Philippines at 19:16 GMT. The Super Constellation carried nine hours of fuel for the 1600 mi, 8-hour flight.

Eighty minutes after departure, at 14:22 GMT, the pilot radioed a routine message and gave his position as being 280 miles west of Guam at coordinates (13.66667°N, 140°W). The aircraft was expected to reach 14°N, 135°W at 15:30. At that time, the Guam IFSS experienced temporary communication difficulties with heavy radio static. At 15:39 the Guam radio operator attempted to contact the flight for a position report but was unable to establish contact. The aircraft was not seen or heard from again.

Investigation
The Clark Field Rescue Coordinating Center declared the aircraft missing the morning of 16 March 1962, 24 hours after the final radio message was received. Navy officials reported that they believed that the aircraft had crashed closer to Guam than the Philippines. At the time of the disappearance, the weather was clear and the sea calm. The Navy, Air Force, Coast Guard, and Marines ordered aircraft and ships to the area.

The first day of searching continued overnight. During the first two days of the search, vessels crisscrossed 75000 sqmi of ocean. Secretary of the Army Elvis Stahr told newspapers that "[w]e have not given up hope that it will be found and that those aboard are safe," and that a "maximum effort" was being made. After four days of searching, Major General Theodore R. Milton of the 13th Air Force told newspapers that although the chance of finding survivors was doubtful, every effort would be made "as long as there is any hope at all."

Search efforts included aircraft from Guam, Clark Field, the US 7th Fleet, and the Air Force at Okinawa. Additionally surface ships and aircraft from numerous U.S. bases in the western Pacific contributed to the search efforts.

After eight days, the search was called off. The search, which was, at the time, one of the largest to ever take place in the Pacific, had covered more than 200000 sqmi of ocean.

Conspiracy theories
Two Flying Tiger Line aircraft carrying military aid to South Vietnam were destroyed under similar circumstances on the same day, leading to "wild guesses" of sabotage and conspiracy by both airline officials and the media. Both Flight 739 and another L-1049 Super Constellation departed from Travis Air Force Base at around 9:45 PST on Wednesday 14 March 1962 to Saigon on behalf of the Department of Defense, and both encountered difficulties several hours later. The other aircraft was carrying "secret military cargo" when it crashed in the Aleutian Islands and caught fire.

Flying Tiger Lines released a statement outlining some possible reasons for the two occurrences, including sabotage of either or both aircraft, and kidnapping of Flight 739 and its passengers. The airline also said that these were merely "wild guesses" and that there was no evidence to support either theory.

Possibility of sabotage
A Liberian tanker, the SS T L Linzen, reported seeing a bright light in the sky near the aircraft's expected position about 90 minutes after the last radio contact. US military officials described it as being a “bright light strong enough to light” a ship’s decks. The Spokane Daily Chronicle reported that the tanker observed a flash of light approximately 500 mi west of Guam, followed immediately by two falling red lights falling to the ocean at different speeds.

A Civil Aeronautics Board investigation determined that witnesses aboard the tanker also observed what appeared to be vapor trails, and numerous crew members observed the two fireballs fall into the ocean. The tanker proceeded to the location where the fireballs had been observed to impact the ocean but was unable to find any trace of the falling objects during their six-hour search. A spokesman at the rescue effort headquarters in Guam said that as time passed with no sign of the aircraft, "more credence is given to the possibility that the tanker may have seen the missing aircraft explode in flight.”

Officials with the Flying Tiger Line said that if the investigation reveals that an explosion occurred on board the aircraft, it would support their earlier theories of sabotage. The executive vice president of operation told the Associated Press that experts consider it impossible for explosions to occur on the Super-Constellation in the course of normal operation. Additionally he claimed that there is nothing powerful enough aboard the aircraft to completely blow apart the vessel, and that "something violent must have happened."

The Civil Aeronautics Board determined that, given the observations of the tanker crew, the flight most likely exploded in midair. As no part of the wreckage was ever found, the CAB was unable to make a determination as to a determination of cause. The accident report concluded: A summation of all relevant factors tends to indicate that the aircraft was destroyed in flight. However, due to the lack of any substantiating evidence the Board is unable to state with any degree of certainty the exact fate of N 6921C.