Narrative: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 oscillations 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 of the pylon, which was already reduced by the presence of the fatigue crack near the forward end of the pylon's forward firewall web."
» Air Safety Week 7:14 5.4.1993 (5)
» NTSB Safety Recommendations A-94-9 and -10
Official accident investigation report
|investigating agency: ||National Transport Safety Bureau (NTSB) - United States of America |
|report status: ||Final|
|report number: ||NTSB/AAR-93/06|
|report released:||13 October 1993|
|duration of investigation: ||196 days (7 months)|
|download report: ||
Follow-up / safety actions
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 to Chicago-O'Hare International Airport, IL as the crow flies is 4534 km (2834 miles).