Incident Overview
Date: Monday 13 December 1999
Aircraft Type: Boeing 777-222ER
Owner/operator: United Airlines
Registration Number: N786UA
Location: NW of London-Heathrow Airport (LHR/EGLL) –
ÿ United Kingdom
Phase of Flight: En route
Casualties: Fatalities: 0 / Occupants: 190
Component Affected: Autopilot system and speed brakes.Autopilot system and speed brakes.
Investigating Agency: AAIBAAIB
Category: Accident
An aircraft inbound to London Heathrow experienced severe turbulence due to an overcast cloud layer, followed by an overspeed warning alert. The autopilot was disconnected, and speed brakes were deployed manually. Subsequently, the aircraft experienced significant turbulence lasting less than 30 seconds, leading to injuries among flight attendants. A purser notification of injured flight attendants followed.An aircraft inbound to London Heathrow experienced severe turbulence due to an overcast cloud layer, followed by an overspeed warning alert. The autopilot was disconnected, and speed brakes were deployed manually. Subsequently, the aircraft experienced significant turbulence lasting less than 30 seconds, leading to injuries among flight attendants. A purser notification of injured flight attendants followed.
Description
The aircraft was inbound to London Heathrow on a scheduled passenger flight from Chicago (USA). During the descent, the aircraft entered an overcast cloud layer and, shortly afterwards, the overspeed warning alert sounded. The autopilot was disconnected and the speedbrakes were deployed manually to slow the aircraft. Approximately one minute later, the aircraft experienced severe turbulence that lasted less than 30 seconds. Shortly after this event, the purser contacted the flight deck crew to inform them that several flight attendants had been injured during the turbulence. One flight attendant sustained a fractured right fibula above the ankle when a passenger fell and collided with her.
Primary Cause
Overspeed warning alert triggered by inclement weather conditions (overcast cloud layer and turbulence).Overspeed warning alert triggered by inclement weather conditions (overcast cloud layer and turbulence).Share on:
