Japan Airlines Flight 422 accident

Japan Airlines Flight 422 (JL422) was an international scheduled flight from Paris via London and Anchorage to Tokyo. On 16 December 1975, the Boeing 747 registered JA8122 operating the flight slid off an icy taxiway at Anchorage International Airport, seriously injuring 2 people and slightly injuring 9.

Course of the accident

Flight JL422 arrived in Anchorage from London at 17:42, after which the crew was changed. At the time light snow was falling around Anchorage Airport and there was also residual ice and snow, but the snow on the runways had later been cleared by airport staff. At 17:57 a southeasterly wind began blowing around the airport at 22 knots, the ground temperature fell below freezing, and light rain began falling around the airport at 18:15.

At 19:04 Flight JL422 left the terminal and taxied along the east-west taxiway parallel to runway 06/24 to runway 6R. The wind at the time was from 120°-130° at 15 to 32 knots. The captain was concerned at the time that the crosswind exceeded 20 knots, but the braking system was normal during taxiing. The first officer, however, stated that the aircraft had a tendency to slide on the taxiway.

As he began the takeoff, the captain heard a noise from the left side resembling a compressor stall and immediately aborted the takeoff. The first officer stated that the engine pressure ratio had risen from 1.3 to 1.4 at the time, and the flight engineer saw the needle of the second pressure ratio indicator fluctuating. The aircraft then taxied back to the terminal, by which time the pressure ratio of the No. 2 engine had risen to 1.46.

At 19:42 the aircraft returned to the terminal for inspection of the No. 1 and No. 2 engines, and fuel was added up to 7,000 pounds to replace fuel consumed while waiting. At this point the captain received a telex from JAL's Tokyo headquarters informing him that Haneda Airport banned landings after 23:00 Japan local time, so Flight JL422 would need to take off before 21:00 Alaska time in order to reach Tokyo before the curfew began. The captain then decided to taxi to the runway again.

At 20:04 Flight JL1008 (a DC-8), which had taken off from runway 6L, reported the taxiing and takeoff conditions to the JAL dispatcher, and the captain of Flight JL422 also learned of this on the JAL frequency. Airport staff estimated the braking conditions on the runway at around 20:20 but did not check the taxiways. 10 minutes later Flight JL422 was pushed back from the boarding gate, but it was delayed because the aircraft tug slipped on the ice. At 20:30:30 the Federal Aviation Administration ground controller in the tower informed Wien Air Alaska Flight 15 that the apron was slippery and the taxiways leading to runways 6L and 6R were "very slippery". At 20:35:25 the driver of an airport maintenance truck informed the tower. Runway 6R was slippery, so sand needed to be spread immediately.

11 minutes later Flight JL422 requested taxi instructions, and the tower advised it to use runway 6L or 6R, with the wind from 140° at 25 knots. The captain chose to take off from runway 6R, crossed runway 13/31 and began taxiing on the east-west taxiway leading to runway 6R, but staff had not previously taken anti-skid measures such as spreading sand or urea on the taxiway. The aircraft taxied at an average speed of 9.9 knots, while the inertial navigation system showed its speed between 5 and 10 knots. At 20:53 the tower told Flight JL422 to taxi with caution, as the taxiway was "extremely slippery". The captain later said that taxiing was not difficult, but after the tower's warning the aircraft began to slide to the right; the captain tried to use nose-wheel steering and braking to bring the aircraft back into position, and after the speed dropped to 5 knots it began to slide again, with the nose deviating 10° to 15° from the taxiway centreline. The captain then applied maximum braking, but the aircraft was still sliding, so he had to increase reverse thrust on all four engines, and the aircraft stopped sliding. Suspecting that the aircraft's taxi lights had been struck, the captain shut down all engines and told the first officer to call a tug to tow the aircraft back.

The aircraft then tilted to the right, with the angle between the nose heading and the taxiway reaching 70°. The aircraft then slid backwards, struck an embankment, and finally came to rest perpendicular to the taxiway with its right wing close to the ground; the slope at the site was about -13°. The flight attendants then began directing those on board in an emergency evacuation, and all passengers escaped within 60 seconds. The aircraft did not catch fire; the captain and one passenger suffered compression fractures of the lumbar spine, and the flight engineer, one flight attendant and 7 passengers were slightly injured in the accident.