Boeing 747-422 N178UA

Summary

On 14 November 2003 at about 20:50 local time, a Boeing 747-422 registered N178UA, operated by United Air Lines Inc, was involved in an accident near San Francisco, California, United States. 356 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

14 November 2003 at 20:50

Classification

Accident

Location

San Francisco, California, United States

Nearest airport

San Francisco International (SFO)

Coordinates

37.6189, -122.3914

Aircraft

Boeing 747-422

Registration

N178UA

Category

Airplane

Engines

4

Operator

United Air Lines Inc

Operating rule

Part 121: Air Carrier

Phase of flight

Not recorded

Route

San Francisco → Hong Kong

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX04LA050

Nobody was injured.

a tail strike due to a combination of the wind shifting from a headwind to a tailwind during rotation, and the pilot's control inputs for the crosswind condition.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The airplane experienced a tail strike on rotation. The first officer was the flying pilot for the takeoff on runway 10L. The winds were from 180 degrees at 16, gusting to 22 knots. The takeoff roll was normal, and the flying pilot utilized control wheel input to correct for the crosswind. A few seconds after rotation, the crew noted the stick shaker annunciate, and flying pilot responded by gently easing back pressure off the control yoke. The crew returned to land at the departure airport after controllers in the tower reported that the airplane may have struck the tail. Flight Data Recorder (FDR) information indicated that the takeoff occurred during directionally variable wind conditions. The wind shifted during the takeoff roll, resulting in a decreasing headwind, an increasing crosswind, and finally to an average 8-knot tailwind during rotation. The maximum pitch rate during rotation was slightly higher than average, but within the normal expected variation. Analysis of the data showed this was a minor contributor to the tail strike. The flying pilot used significant wheel input (35 degrees right wheel) to counter the increasing crosswind, which resulted in the right spoiler raising 12 degrees and a corresponding loss of lift due to the use of spoilers. Rotating at a lower airspeed requires a higher angle of attack, and therefore, a higher pitch attitude to achieve liftoff. The combination of the tailwind gust and spoiler movement resulted in the airplane's pitch attitude exceeding 12.6 degrees while the gear was still on the ground. This resulted in the aft body contact with the runway. During a typical takeoff in gusty or strong crosswind conditions, the manufacturer recommended maximum takeoff thrust and to avoid rotation during a gust. Slightly delaying rotation would allow the airplane additional time to accelerate through the gust, and the greater airspeed would improve the tail clearance margin. The FDR-recorded longitudinal control system parameters suggested a properly functioning system. The airplane motion was consistent with the control inputs and power settings.

Quoted verbatim from the NTSB record.