The AAIB has released a further update on their investigation into the cause of Boeing 777 crash at London Heathrow.

Boeing 777-236 G-YMMM of the British Airways fleet crashed with no loss of life 300m short of the threshold of 27L at Heathrow on the 17th of January.

In the preliminary report it was established that neither engine responded to either autothrottle commands or manual throttle inputs during the last 40 or so seconds of flight.

The investigation has now revealed that the engines initially responded and then became asymmetric before both engines dropped to a power setting above flight-idle but below the requested setting.

From the report update:

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.

The full text of the update is available HERE

The AAIB will continue to investigate the accident and while a full report may be many months or even more than a year away, they will undoubtedly update manufacturers and operators of the 777 if they find any critical flaw in the design of the aircraft or systems.

Photo Credit: Adrian Pingstone

In a preliminary report from the AAIB on Thursday’s Boeing 777 crash at London Heathrow (British Airways Flight BA38) in which all 136 passengers and 16 crew survived, it is suggested that ‘unresponsive’ engines are at fault after brief Flight Data Recorder analysis.

In an earlier press conference held at British Airways headquarters, it was stated by Capt. Peter Burkill that his first-officer, John Coward was the handling pilot at the time of the crash.

Following an uneventful flight from Beijing, China, the aircraft was established on an ILS approach to Runway 27L at London Heathrow. Initially the approach progressed normally, with the Autopilot and Autothrottle engaged, until the aircraft was at a height of approximately 600 ft and 2 miles from touch down. The aircraft then descended rapidly and struck the ground, some 1,000 ft short of the paved runway surface, just inside the airfield boundary fence. The aircraft stopped on the very beginning of the paved surface of Runway 27L. During the short ground roll the right main landing gear separated from the wing and the left main landing gear was pushed up through the wing root. A significant amount of fuel leaked from the aircraft but there was no fire. An emergency evacuation via the slides was supervised by the cabin crew and all occupants left the aircraft, some receiving minor injuries.

At 600 feet, two miles out from 27 left on the extended centre-line, the autothrottles commanded increased power but the engines did not respond. The flight crew then moved the throttles manually with the same result. This situation is reported to have continued until the aircraft touched down about 300m from the threshold.

Initial indications from the interviews and Flight Recorder analyses show the flight and approach to have progressed normally until the aircraft was established on late finals for Runway 27L. At approximately 600 ft and 2 miles from touch down, the Autothrottle demanded an increase in thrust from the two engines but the engines did not respond. Following further demands for increased thrust from the Autothrottle, and subsequently the flight crew moving the throttle levers, the engines similarly failed to respond. The aircraft speed reduced and the aircraft descended onto the grass short of the paved runway surface.

As yet there is no word on the reason for the APU door being open as observed. All such information about the aircraft state on landing will probably come in the formal report.

As stated in the short preliminary report, the investigation into the crash of G-YMMM will continue until it’s culmination in a full formal report at some point in the future. There may be another ’special’ report a month or so from now.

Full Text Initial Report AAIB Ref: EW/C2008/01/01

Photo Credit: Marc-Antony Payne cc-by-3.0

Read on for the full text of the original initial report:

(more…)

A Boeing 777-200ER (Reg G-YMMM) has undershot runway 27L at Heathrow today and pretty much crashed in the process.

The aircraft which was inbound from Beijing China to Heathrow UK as British Airways flight BA038 (also reported as BA38) touched down about 300 meters from the threshold on the extended centre line of 27 Left. This was within the airfield boundary but on the cut-grass section before the hard-surface of the runway begins.

The aircraft appears to have touched down with the gear deployed but with sufficient force as to almost immediately collapse the maingear and partially collapse the nosegear. The initial contact marks in the grass indicate the maingear touchdown point and in only 30 meters or so, the engine nacelles contacted the ground and left larger gouge-marks in the grass which obscure any sign of the nosewheel contact point. The aircraft then tracked straight toward the runway threshold for about another 200meters before beginning to turn to the right and coming to a hold roughly adjacent the threshold.

The cabin crew successfully evacuated the aircraft via the inflatable emergency slides which were deployed at all the normal exit doors. Some passengers have been treated for minor injuries. The airfield fire service attended and foamed the area to reduce the risk of fire. The aircraft in it’s final resting position had almost completely collapsed maingear, the undercarriage having apparently pushed up through the latter quarter of the wingroots and disrupted the wingroots and the flaps which were set at an apparently normal angle. Some undercarriage components appear to have separated prior to the aircraft coming to rest. The leading edge slat were also configured for landing. The engine nacelles were disrupted by impact with the ground but the engines themselves remained fully attached but the pylons were pushed upwards. It was impossible to tell from the television images whether reverse thrust had been selected or begun to deploy at any point prior to the engines being damaged.

The airfield was closed for a time due to the airfield fire service being unavailable to support other flights. There is also some apparent damage to the taxiway surface to the North of the 27L threshold. I don’t think the ILS equipment was damaged by the aircraft.

There were eye-witness reports from people on the ground watching the approach. They indicate that the approach was abnormal but the reports are conflicting.

My personal speculation would be that a loss of thrust lead to the undershoot. The cause of the loss of thrust would require investigation. The BBC are currently reporting a ‘unknown’ source quoting the pilot as having said that he experienced a ‘loss of power’ and had to glide in.

There will probably be announcements of the likely cause in due course. A full AAIB report will take much longer although any critical failure of this aircraft design may lead to an early ’special bulletin’ later in the year.

Update: Close examination of television pictures shows that the APU intake door located on the fuselage to the right of the main fin ended up in the open position. The implication being that the APU was air-started in order to provide power which may have been lost from the normal engine-mounted generators. This picture shows a 777 with the APU intake door open. No imagery thus far gives any indication of the position of the Ram Air Turbine(located aft of the starboard maingear) although, if deployed, this would have separated from the aircraft when the gear collapsed.

As an aside, with a landing run of only about 330m, this may be the shortest ever survivable landing run of a Boeing 777.

Naturally getting any useful information from the television news media is nigh-on impossible as they lurch from one newsgasm to the next. I could personally have screamed when they excitedly proclaimed that it had been “confirmed” that this was not a “terrorist-related-incident”. Of course it wasn’t a terrorist incident! Accidents happen all the time and the evil bogey-man doesn’t have a hand in them. In fact, the probability of him having a hand in it is really, really remote so please, TV News, grow up and shut up with the ‘terror angle’. We could also do without television presenters *encouraging* witnesses to relate fear when they clearly weren’t particularly frightened. It ’s a disgusting practice of which so-called ‘journalists’ should be ashamed. You could almost feel the disappointment in the presenters when they were told that there was no panic. </rant>

Photo Credit: Adrian Pingstone