BRITISH ISSUE UPDATE ON B-777 ACCIDENT AT LONDON HEATHROW

[NTSB Press Releases <NTSBPressReleases@xxxxxxxx>]

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                       NTSB ADVISORY
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National Transportation Safety Board
Washington, DC 20594

January 24, 2008

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BRITISH ISSUE UPDATE ON B-777 ACCIDENT AT LONDON HEATHROW

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The United Kingdom's Air Accident Investigation Board 
(AAIB), which is leading the investigation into the January 
17, 2008, accident in which a British Airways Boeing 777-
236ER landed short of Runway 27L at London Heathrow Airport, 
issued a report today on the progress of their 
investigation.

At their request, we are assisting in the dissemination of 
the AAIB report, which follows:

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Accident to a Boeing 777-236, G-YMMM, on 17 January 2008 at 
1243 hrs

Initial Report Update 23 January 2008

Since the issue of the Air Accidents Investigation Branch 
(AAIB) 1st Preliminary Report on Friday 18th January 2008 at 
1700 hrs, work has continued on all fronts to identify why 
neither engine responded to throttle lever inputs during the 
final approach.  The 150 tonne aircraft was moved from the 
threshold of Runway 27L to an airport apron on Sunday 
evening, allowing the airport to return to normal 
operations.
 
The AAIB, sensitive to the needs of the industry including 
Boeing, Rolls Royce, British Airways and other Boeing 777 
operators and crews, is issuing this update  to provide such 
further factual information as is now available.

As  previously reported, whilst the aircraft was stabilised 
on an ILS approach with the autopilot engaged, the 
autothrust system commanded an increase in thrust from both 
engines.  The engines both initially responded but after 
about 3 seconds the thrust of the right engine reduced.    
Some eight seconds later the thrust reduced on the left 
engine to a similar level.  The engines did not shut down 
and both engines continued to produce thrust at an engine 
speed above flight idle, but less than the commanded thrust.

Recorded data indicates that an adequate fuel quantity was 
on board the aircraft and that the autothrottle and engine 
control commands were performing as expected prior to, and 
after, the reduction in thrust.

All possible scenarios that could explain the thrust 
reduction and continued lack of response of the engines to 
throttle lever inputs are being examined, in close 
cooperation with Boeing, Rolls Royce and British Airways.  
This work includes a detailed analysis and examination of 
the complete fuel flow path from the aircraft tanks to the 
engine fuel nozzles.  

Further factual information will be released as and when 
available.

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The AAIB will continue to release all information on the 
progress of their investigation.

NTSB Media Contact: Peter Knudson, 202-314-6100
peter.knudson@xxxxxxxx


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