Accident description
languages:
| Status: | Final |
| Date: | 31 MAR 1993 |
| Time: | 12:34 AST |
| Type: | Boeing 747-121 |
| Operator: | Japan Air Lines - JAL |
| Registration: | N473EV |
| C/n / msn: | 19657/37 |
| First flight: | 1970-04-15 (22 years 12 months) |
| Total airframe hrs: | 83906 |
| Cycles: | 18387 |
| Engines: | 4 Pratt & Whitney JT9D-7D |
| Crew: | Fatalities: 0 / Occupants: 3 |
| Passengers: | Fatalities: 0 / Occupants: 0 |
| Total: | Fatalities: 0 / Occupants: 3 |
| Airplane damage: | Substantial |
| Airplane fate: | Repaired |
| Location: | Anchorage International Airport, AK (ANC) (United States of America)
 |
| Phase: | Initial climb (ICL) |
| Nature: | Cargo |
| Departure airport: | Anchorage International Airport, AK (ANC/PANC), United States of America |
| Chicago-O'Hare International Airport, IL (ORD/KORD), United States of America | |
| Flightnumber: | 46E |
JAL Flight 46E departed Anchorage about 12:24 local time. The flight release/weather package provided to the pilots by Evergreen operations contained a forecast for severe turbulence and indicated that severe turbulence was reported by other large airplanes. As flight 46E taxied onto the runway to await its takeoff clearance, the local controller informed "the flightcrew that the pilot of another
Evergreen B-747 reported severe turbulence at 2,500 feet while climbing out from runway 06R.
After takeoff, at an altitude of about 2,000 feet, the airplane experienced an uncommanded left bank of approximately 50 degrees. While the desired air speed was 183 knots, the air speed fluctuated about 75 knots from a high of 245 knots to a low of 170 knots. Shortly thereafter, the flightcrew reported a "huge" yaw, the No. 2 throttle slammed to its aft stop, the No. 2 reverser indication showed thrust reverser deployment, and the No. 2 engine electrical bus failed. Several witnesses on the ground reported that the airplane experienced several severe pitch and roll osciliations before the engine separated. Shortly after the engine separated from the airplane, the flightcrew declared an emergency, and the captain initiated a large radius turn to the left to return and land on runway 06R. The No. 1 engine was maintained at
emergency/maximum power. While on the downwind portion of the landing pattern, bank angles momentarily exceeded 48 degrees, alternating with wings level. About 12:45, flight 46E advised the tower that they were on the runway.
PROBABLE CAUSE: "The lateral separation of the No. 2 engine pylon due to an encounter with severe or possibly extreme turbulence that resulted in dynamic multi-axis lateral loadings that exceeded the ultimate Iateral load-carrying capability af the pylon, which was already reduced by the presence of the fatigue crack near the forward end of the pylon's forward firewall web." Follow-up / safety actions:
As a result of its investigation of this accident, the NTSB made 7 recommendations to the FAA, including the inspection of B-747 engine pylons, the potential meteorological hazards to aircraft, an increase in the lateral load capabiiity of engine pyton structures, and the modification of the aircraft departure routes at Anchorage International Airport during periods of moderate or severe turbulence. The Safety
Board recommended that the National Weather Sewice use the WSR-88D Doppler weather radar system at Anchorage, Alaska, to document mountain-generated wind fields in the Anchorage area and to develop detailed low altitude turbulence forecasts. Additionally, the Safety Board reiterated to the FAA Safety Recommendation A-92-58. which urged the development of a meteorological aircraft hazard program to include other airports in or near mountainous terrain.
Sources:
» Air Safety Week 7:14 5.4.1993 (5)
» NTSB Safety Recommendations A-94-9 and -10
» NTSB/AAR-93/06
Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Anchorage International Airport, AK (ANC/PANC) to Chicago-O'Hare International Airport, IL (ORD/KORD) as the crow flies is 4624 km (2890 miles).
Distance from Anchorage International Airport, AK (ANC/PANC) to Chicago-O'Hare International Airport, IL (ORD/KORD) as the crow flies is 4624 km (2890 miles).
