Boeing 747-236B, G-BDXP, 12 December 2000

Boeing 747-236B, G-BDXP AAIB Bulletin No: 5/2002 Ref: EW/C2000/12/05 Category: 1.1 INCIDENT Aircraft Type and Registration: Boeing 747-236B, G-BDXP No & Type of Engines: 4 Rolls-Royce RB211-524D4-19 turbofan engines Year of Manufacture: 1988 Date & Time (UTC): 12 December 2000 at 1938 hrs Location: London Heathrow Airport Type of Flight: Public Transport (Passenger) Persons on Board: Crew -18 Passengers - 116 Injuries: Crew - None Passengers - None Nature of Damage: None Commander's Licence: Airline Transport Pilot's Licence Commander's Age: 47 years Commander's Flying Experience: 11,336 hours (of which 6,344 were on type) Last 90 days - 112 hours Last 28 days - 71 hours Information Source: AAIB Field Investigation History of the flight The flight departed from Boston USA and was inbound to London Heathrow Airport (LHR). The 1800 hrs Terminal Aerodrome Forecast (TAF) for LHR, obtained en-route by the crew, indicated that surface winds could increase to a value in excess of the aircraft crosswind limitation at the expected time of arrival. The crew reviewed the available alternates and decided that London Stansted Airport would be the most suitable in the event of LHR being unavailable. At 1917 hrs the aircraft was required to hold in the London area awaiting an approach. The crew asked London Area and Terminal Control Centre (LATCC) whether Runway 23 would be available in view of the wind conditions. They were advised that it was but would entail a 20 minute delay for the flight. In light of this information, together with the fact that the surface wind remained within limits for Runway 27R and that an ILS approach would be preferred the commander elected to continue for an approach for Runway 27R, the landing runway scheduled for use until 2359 hrs. The First Officer (FO) flew the approach with the autopilot engaged. At about 1,000 feet agl the Flight Engineer (FE) advised the others of the Inertial Navigation System (INS) derived wind; 206°/45kt with a drift of 16.1°. ATC advised another aircraft ahead on the approach that severe turbulence could be expected around the area of the hangars on short final. A question was raised amongst the incident crew as to why the airport was using this runway in these conditions as from their own previous experience Runway 27L would be preferable. At 700 feet agl with visual contact established the commander took control, in accordance with company standard operating procedures, and then disengaged the autopilot. Flap 25 with a VREF speed of 135 kt was used for landing. The FE read out a drift angle of 12° at touchdown. The touchdown was made at 150 kt on a heading 8o left of the runway QDM of 273°M, smoothly and close to the centreline. Autospeedbrake deployed normally. After touchdown the aircraft initially tracked towards the left of the runway despite the commander's attempts to maintain the centreline by the use of full right rudder. The left wing of the aircraft lifted to give a right roll attitude of 4° and then returned to level. The FO delayed the selection of reverse thrust until he was confident that the aircraft was under control. The aircraft tracked back towards the runway centreline and thrust reversers were then deployed at a speed of 110 kt. The centreline was regained and the aircraft began to track slightly to the right. An input of 70% left rudder was used for a short time to counter this and the aircraft swung rapidly to the left. Reverse thrust was cancelled and the commander attempted to use the steering tiller to regain control but felt the nosewheel scrubbing across the runway surface. The left wing briefly lifted again. Full right rudder was reapplied but the aircraft continued tracking to the left and came off the paved area into a grass triangle between two taxiways. The aircraft came to rest on the grass and the flight crew assessed the possible damage. The commander consulted with the attending Heathrow Fire Service and decided that it was not necessary to carry out a passenger evacuation of the aircraft and completed a normal shutdown. The emergency services confirmed that there was no apparent damage to the aircraft. There was some delay before steps could be attached and passengers disembarked because of the difficult ground and wind conditions. Meteorological conditions The synoptic situation at 1900 hrs on 12 December 2000 showed a low pressure area centred over north-west Ireland with a cold front lying from South Wales to Western Scotland and a trough lying 40 nm west of London. A very strong southerly airstream covered the Heathrow area. The 1920 hrs ATIS report for LHR included the following; "landing Runway 27R, surface wind 190°/21 kt gusting to 32 kt, varying between 160° and 220°, visibility 10 km, moderate rain, cloud broken at 1,300 feet and overcast at 1,800 feet, temperature 13°C, dewpoint 11°C and QNH 998 mb pilots be advised turbulence may be experienced during the last mile of final approach to Runway 27R and windshear has been forecast". This information was included as a result of an instruction in the Manual of Air Traffic Services (MATS) Part 2 for LHR requiring a message to be broadcast if the surface wind is between 170° and 230° in direction and exceeds 15 kt. There was no similar requirement for Runway 27L. A Meteorological Office anemograph trace was available for the investigation. The anemometer was located in a position near to the threshold of Runway 09R, some 1 to 2 nm from the relevant section of Runway 27R. These traces recorded a minimum wind speed of 12 kt and a maximum of 36 kt in a two-minute period around the time of the incident. Data was also available from a touchdown sensor for Runway 27R. This data gives a 2-minute mean wind speed and the maximum and minimum values over a 10-minute period. The values recorded at 1938 hrs were as follows; mean wind speed 25 kt, maximum 33 kt and minimum 15 kt, mean wind direction 198°M, maximum 220°M and minimum 180°M. The tower reported wind passed to the aircraft with the landing clearance was 200°M/31 kt. The runway condition was wet. Subsequent to the incident a grip test on Runway 27R was carried out by the airport operator and a braking condition 'good' reading was obtained. The aircraft The aircraft centre of gravity was calculated to have been in the middle of the allowable range. The landing weight of the aircraft was 216 tonnes, the maximum allowable was 285 tonnes. The aircraft had one significant outstanding technical defect, an unserviceable autothrottle system. This defect caused the orange reference speed 'bug' to remain fixed at 290 kt throughout the flight. A manually positioned 'bug' was used instead by the crew for setting the appropriate reference speed and the thrust levers were operated manually. The maximum demonstrated crosswind for the aircraft type on initial certification was 28 kt. The crosswind demonstration was conducted on a dry runway, and this level of crosswind was not considered to be the limiting crosswind condition. In 1995, a need to better understand the aircraft's crosswind capability was identified following a number of crosswind related diversions among operators. The manufacturer carried out a program of simulator trials and engineering analysis that resulted in revised crosswind guidelines. The simulator trials were based on steady wind conditions. The landing crosswind guideline for the 747-200 aircraft was revised to 32 kt on a wet runway and the operator adopted this in September 1996. The recommended technique for landing in a crosswind on a wet surface was to fly the aircraft onto the runway while maintaining the runway centreline track. The Boeing 747 Flight Crew Training Manual states: "It is not necessary to eliminate the crosswind crab angle prior to touchdown on wet runways. Allowing the airplane to touch down without removing the crab angle will r

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Boeing 747-236B, G-BDXP, 12 December 2000

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