FROM : AIRBUS FLIGHT SAFETY DEPARTMENT TOULOUSE
ACCIDENT INFORMATION TELEX - ACCIDENT INFORMATION TELEX
SUBJECT: A310 ACCIDENT IN IRKUTSK, RUSSIA OUR REF.: S7 778 AIT 2 Dated 04th AUGUST 2006.
Previous ref: S7 778 AIT 1 dated July 9th 2006
This AIT is an update of previous AIT n°1 concerning the A310 Siberia Airlines flight S7 778 accident in Irkutsk, Russia which occurred on July 09th 2006.
The following information has been approved for release by the
Interstate Aviation Committee (MAK).
The preliminary analysis of the accident data, including DFDR data,
indicates the following sequence of events:
The aircraft was dispatched with engine 1 (LH) reverse deactivated as per MEL.
The aircraft was approaching runway 30 (taking into account the
displaced Runway threshold, the Landing Distance Available was 2425 meters) with a wind of 285°/10kts, in raining condition.
Landing configuration was established with Slats/flaps fully extended,
gear down, ground spoilers armed. Airspeed and selected approach speed
were 138 kts, ground speed 135 kts. The vertical speed was stabilized around 700 ft/min.
Autopilot and autothrottle were disconnected at 300 ft radio-altitude.
They remained disconnected until the end of the flight.
Final approach was uneventful, with both engines throttles set to Idle position prior to touchdown.
At time of touchdown the airspeed and ground speed were 132 kts.
Upon touchdown, the ground spoilers automatically extended. This was
immediately followed by an increase of the longitudinal deceleration
up to almost 0.2g without brake pedal action. The autobrake was active and worked correctly in Low mode.
Within a few seconds after touchdown, the engine 2 thrust reverse was
selected to idle reverse and then to max reverse. The engine 1 thrust reverse was not selected. This is consistent with the engine reverse 1 deactivated.
Then recorders indicate that engine 2 reverse thrust was progressively reduced until the reverse was stowed and it remained in that position
until the end. At the same time, engine 1 throttle changed position giving significant forward thrust.
The investigation commission is working on determining the possible
sequence of events leading to this throttle asymmetry.
The thrust asymmetry was counteracted with full rudder.
Full manual braking was applied on both pedals about 15 seconds after touchdown.
The a/c overran the end of the runway at approximately 95 knots.
At this stage of the investigation, Airbus has no specific recommendation to give to operators.
An update of this AIT will be provided as soon as valuable information is made available.