Pakistan International Airlines Flight 740

Pakistan International Airlines Flight 740 was a Hajj pilgrimage flight from Kano, Nigeria to Karachi, Pakistan with an intermediate stopover in Jeddah, Saudi Arabia. Operated by Pakistan International Airlines, on 26 November 1979, the Boeing 707-340C serving the route crashed shortly after takeoff from Jeddah International Airport. All 156 people on board were killed.

Aircraft
The aircraft involved was a nine-year-old Boeing 707-340C with serial number 20275 and serial 844. It was built in 1970 and on July 30 made its first flight. Ten days later, on 10 August, it was delivered to Pakistan International Airlines (PIA) and was registered as AP-AWB. It was re-registered as AP-AWZ in 1972 after being leased for several months to another airline. The aircraft had 30,700 flight hours at the time of the crash.

Crash
The airliner operated as flight 740 from Jeddah to Karachi, during which it carried pilgrims returning from the Hajj. There were a total of 156 people on board, 11 crew members and 145 passengers. At 01:29, flight 740 departed from Jeddah and began to climb to the planned flight level (FL) of 37000 ft. The first warning of an emergency came at 01:47, 21 minutes after takeoff, when a flight attendant informed the pilots that a fire had started in the rear of the cabin. After reporting to air traffic control (ATC) about the situation on board and beginning an emergency descent from its current altitude of 30000 ft, the crew received permission to descend to a height of 4000 ft. The pilot radioed a request to return to Jeddah because smoke was coming into the cabin and cockpit. At 02:03 the crew sent a distress signal. The Jeddah control tower heard the pilot shout "Mayday! Mayday!" before the radio went silent. Approximately one minute after this transmission, the aircraft crashed into an area of rocks located 48 km north of the city of Taif and at an altitude of 3000 ft. All 156 people on board died. The accident remains, to date, the third-deadliest plane crash on Saudi Arabian soil and the third-deadliest Boeing 707 crash.

Cause
The cause of the accident was an in-flight fire in the cabin area, which, through its intensity and rapid extension, eventually incapacitated the flight crew. The cause of the cabin fire was not determined. The most likely version is that there was a gas leak or kerosene from one of the pilgrims' stoves. The fuel leakage may have been a result of the decrease in cabin pressure. A malfunction in the electrical circuits was also considered as an ignition source, but could not be confirmed because of the design of the aircraft's electrical systems and protection devices. Terrorism was ruled out as a cause, as there was no evidence that incendiary devices were used.