TWA Flight 800 (1964). Trans World Airlines Flight 800 was an international scheduled passenger service from Kansas City, Missouri to Cairo, Egypt via Chicago, New York City, Paris, Milan, Rome, and Athens. The Boeing 707 caught fire following a rejected take off on runway 25 at Leonardo da Vinci–Fiumicino Airport, Rome at 13:09 GMT on a flight to Athens International Airport, Greece on November 23, 1964, killing 49 of the 74 people on board.

Aircraft and crew
The aircraft was a four and a half year old Boeing 707-331, registered N769TW. Onboard were 62 passengers and 11 crew. The flight crew consisted of Captain Vernon W. Lowell (44), an experienced pilot with 17,408 logged hours, 2,617 of those in the Boeing 707. The First Officer was William A. Slaughter (46) who had 17,419 hours overall and 1,269 on the 707. Second Officer John W. Churchill (41) was the least experienced amongst the flight crew with 9,928 hours in total and 1,920 hours on the 707. The Flight Engineer, H. W. Lowery (47) had a total of 14,231 hours with 1,308 of those on the type. There were also six flight attendants and one extra crewmember in the cockpit.

Incident
At the time of the accident, maintenance work was being carried out at the end of runway 25 with the last 2,000 feet of the runway closed. As the aircraft reached 80 knots during its take off roll, the instruments for engine number 4 indicated zero thrust. The flight crew assumed that this engine had failed. Seconds later the Reverser Unlock light for Engine number 2 illuminated. Since the aircraft was below its V1, the safest course of action was to abort the take off, which was done when the aircraft was around 800 metres along the runway. This was accomplished by ordering full reverse thrust on all engines, as well as deploying their thrust reversers. The aircraft began to slow down, but not as quickly as expected; Captain Lowell also had great difficulty maintaining directional control.

The 707 overran the declared end of the runway and struck a compactor crossing the runway, damaging the Number 4 engine and started a fire on the right wing. The aircraft eventually stopped a further 260 metres down the runway and an evacuation began. Only seconds after coming to a stop the center fuel tank exploded. The evacuation was greatly impeded by smoke and flames blocking most of the passenger exits. More explosions followed including that of the Number 1 fuel tank. Only 24 out of the 73 people onboard survived. Captain Lowell and Second Officer Churchill were among the survivors. A prominent fatality was passenger the Most Reverend Edward Celestin Daly, OP, Bishop of the Roman Catholic Diocese of Des Moines, Iowa, in the United States, who had just participated in Vatican Council II.

One passenger died of her injuries over a month after the accident.  The final report listed her injuries as serious.

Cause

The root cause of the accident was determined to be an inoperative number 2 engine reverse thrust system, even though cockpit instruments showed that the reverser had deployed. This was caused by the disconnection of a duct, resulting in a lack of pressure in the pneumatic clamshell door actuating mechanism. This malfunction allowed the development of considerable forward thrust by number 2 engine even though the thrust levers for all four engines were in the "reverse" position, which both increased the plane's stopping distance as well as giving it a tendency to steer to the right.

The amount of available runway was judged safe as required by the Boeing 707 for take off, rejected take off or landing. But no allowances were made for an aircraft that was not functioning normally, as in the case of Flight 800. Thus the thrust asymmetry resulted in aircraft unable to stop before the end of the declared runway available and avoid the compactor, resulting in the collision and subsequent fire.

Despite the aircraft crew following proper procedures for a rejected take off (powering down engines and hydraulic systems) after the aircraft halted, fuel leaking from the wing tanks connected to the damaged pylon caught fire, likely due to exposed and sparking electrical wiring caused by the damage. After being informed of the fire the crew activated the engine fire-suppression systems, but this had no effect as the fuel and flames had already spread to the point that they hindered evacuation efforts. Eventually the fire reached the fuselage fuel tanks, which were mostly empty except for volatile fuel vapours that ignited and exploded, destroying the aircraft.

Captain Vernon Lowell would go on to become a passionate advocate for improved safety in the aviation industry following this accident and in 1967 wrote a book, Airline Safety is a Myth in which he detailed the accident. Many of his suggestions were subsequently implemented.

References

External links
 ICAO Circular

Aviation accidents and incidents in 1964
Aviation accidents and incidents in Italy
Accidents and incidents involving the Boeing 707
800
1964 in Italy
November 1964 events in Europe
Airliner accidents and incidents caused by engine failure
Airliner accidents and incidents involving ground collisions