Boeing 707-331B accident at US, 8 Sept 1974

Accident narrative

On September 8, 1974, at 0940 Greenwich mean time, Trans World Airlines Flight 841, a Boeing 707-331B, crashed into the Ionian Sea about 50 nautical miles west of Cephalonia, Greece. All 79 passengers and 9 crewmembers aboard were killed, and the aircraft was destroyed.

### The flight

Trans World Airlines (TWA) Flight 841 was a regularly scheduled international passenger and cargo flight from Tel Aviv, Israel, to New York, New York, with scheduled stops in Athens, Greece, and Rome, Italy.

The flight departed Tel Aviv, delayed 43 minutes by passenger security procedures. It landed at Athens at 0804 without any reported mechanical difficulties. Fifty-six passengers deplaned, and 30 boarded, bringing the passenger total to 79. Baggage and cargo were loaded into the forward and rear cargo compartments.

The flight departed Athens at 0912 on an instrument flight plan to Rome. At 0930, the flight reported level at flight level 280 (FL 280). This was the flight's last known radio transmission.

### The sequence of events

At 0939, Pan American Flight 110, flying eastbound at FL 330, entered the Athens Flight Information Region. At 0940, the captain of Pan Am 110 alerted Athens air traffic control that he had seen a four-engine aircraft going down.

The captain stated he first saw the TWA aircraft about 4,000 feet below him in level flight. When he looked again, the aircraft was in a steep climb. As it passed abeam of Pan Am 110, it rolled to the left into a steep descent. The captain noticed an engine was missing and saw a whitish vapor coming from the left wing. He also saw debris below the aircraft that looked like pieces of paper fluttering down.

The first officer and flight engineer of Pan Am 110, as well as two passengers, also observed the aircraft spinning or rolling into a dive, and noted the vapor and fluttering debris. None of the witnesses saw the aircraft strike the water.

### What the investigation found

Search and rescue aircraft located debris and bodies about two and a half hours after the accident. Surface ships recovered the bodies of 24 passengers and floating debris. Medical examinations of the recovered bodies showed injuries consistent with impact; none showed signs of drowning, burns, or the effects of an explosive device.

The flight data recorder and cockpit voice recorder were not recovered. The flight data recorder's locator beacon was detected at a depth of 10,380 feet, but the Board decided the uncertain contribution of the wreckage did not justify the high cost of recovery.

The recovered debris consisted mostly of nonstructural interior items, passenger luggage, and a few structural pieces, including two crumpled pieces of the aft cargo door. Investigators selected several items for laboratory examination, including a punctured suitcase lid, a seat cushion, a floor panel section, and the aft baggage door parts. Independent examinations by the Federal Bureau of Investigation and the United Kingdom's Royal Armament Research and Development Establishment found that metal fragments embedded in these items exhibited deformation, spalling, and micro-structures typical of explosively formed fragments. Both laboratories concluded the objects were damaged by the detonation of a high-order explosive.

The Board analyzed factors that could cause a sudden loss of control. Evasive maneuvers and in-flight turbulence were ruled out. The Board also concluded that an engine separation alone, or a single flight control system malfunction, could not produce a pitchup violent enough to cause the observed structural damage. However, a performance study showed the maneuver was compatible with nearly simultaneously applied elevator and rudder displacements. The control cables for these systems were routed beneath the cabin floor.

The Board noted a previous incident on August 26, 1974, in which a passenger's suitcase containing a malfunctioning explosive device caused a fire in the rear cargo compartment of another TWA Flight 841 from Athens to Rome.

The Board believed that the detonation of an explosive device in the aft cargo compartment buckled and damaged the cabin floor, stretching or breaking the elevator and rudder control cables. The resulting displacement of the control surfaces caused a violent pitchup and yaw, making the aircraft uncontrollable. The Board believed the No. 2 engine most likely separated due to the resulting inertia and air loads, releasing fuel that witnesses saw as vapor, and that the explosive decompression expelled contents of the cargo compartment, which witnesses saw as fluttering paper.

### Probable cause

The National Transportation Safety Board determined that the probable cause of this accident was "the detonation of an explosive device within the aft cargo compartment of the aircraft which rendered the aircraft uncontrollable."