On 29 August 2009, a Boeing 737-800 (7T-VJK) being operated by Air Algérie on a scheduled passenger flight from Lyon to Sétif, Algeria under callsign DAH1155 left the runway during the daylight take off roll in normal ground visibility before regaining the paved surface and completing the take off and continuing, damaged as a result of collision with obstructions, to destination. None of the 46 occupants were injured and damage to the aircraft other than multiple fan blade distortions and damage to both nosewheel tyres was minor.
An Investigation was carried out by the French Bureau d'Enquêtes et d'Analyses (BEA). Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR) downloads covering the event were available to the Investigation as was the ATC ground radar recording and the marks made by the landing gear as the aircraft left the runway, travelled on the grass and then regained it (see the diagram below).
It was noted that the 57 year-old aircraft commander, who had overall flying experience commensurate with age, had been promoted to Captain with the operator after 20 years service as a First Officer almost 10 years prior to the investigated incident. He had logged 3500 hours in command on the Boeing NG. The 31 year-old First Officer was recorded in the Investigation Report as holding an Algerian PPL issued in 2005 and as having acquired just over 1000 hours experience on type out of 2100 hours in total, having joined the operator soon after issue of his PPL initially on the ATR 72.
It was established that after the crew had wrongly reported that they had reached the holding point for the 4000 metre long departure runway 36L when they were still about 240 metres from it, a take off clearance had been issued with approximately 140 metres still to go. After first stabilising the engines at 40% N1, the aircraft commander as PF had begun to set the calculated reduced take off thrust symmetrically and progressively when the aircraft was still about 20 metres from the holding point, but he had not been prepared for the effect of this action on his ability to maintain the indicated and intended track onto the runway centreline with such a lightly-loaded aircraft. As a result of the premature application of thrust, the aircraft then left the right hand side of the 45 metre wide runway (opposite to the entry taxiway) at a recorded ground speed of 61 knots, then travelled for about 250 metres on the grass shoulder parallel to it before hitting and destroying a runway edge marker as it rejoined the paved surface at 92 KCAS (77 knots ground speed) and continuing to complete the take-off. Recorded data showed that the actual rotation speed had been 161 KCAS compared to the planned VR recorded on the flight documents of 129 KIAS.
On arrival in Sétif, the aircraft was found to have sustained damage to 24 of the right engine fan blades, to the right side landing light, to the lower anti collision beacon and to both nose landing gear tyres. The runway excursion was not reported to ATC who had not observed it. Awareness of the event was only gained some eight hours later after the operator’s operations control sent a telex to their company station manager at Lyon asking him to request that the airport carry out a runway inspection because of damage to the aircraft involved which had been found on arrival at Sétif.
CVR data showed that during the climb out, the First Officer had asked the commander about what had happened during take-off and he had replied to the effect that “he had tried his best from the start, but that he couldn't get the aircraft back” and that “he had then slightly reduced the power of the left engine to get the aircraft back on the runway”. There was no further discussion of the incident during the remainder of the flight and it was not mentioned to the Senior Cabin Crew Member.
The flight documents indicated a take-off weight of 54.9 tonnes - well within the MTOM of 78.2 tonnes - and a take-off C of G towards the allowable aft limit. It was noted that the surface wind given by ATC at the time the take off clearance was from 360° at 13-20 knots and it was considered that this would have been unlikely to have been a factor in the excursion.
The tracks of the main landing gear (aircraft came from the lower edge of the picture then regained the runway near the top of the picture after travelling at speed on the grass (reproduced from the Official Report)
In respect of the departure from the runway, the Investigation was of the opinion that:
“In the course of the turn (onto the runway), the nose gear skidded badly, because it was positioned at right angles to the track of the aircraft, leaving a single tyre mark. The fact that the centre of gravity of the aircraft was to the rear, and the force of the acceleration combined with the absence of any forward movement of the handle, contributed to the aircraft's skidding. Moreover, no attempt was made to brake the main landing gear. The PF, taken by surprise by the acceleration of the aircraft and by the rapid deterioration of the situation, did not disengage the A/T to reduce the speed of the two engines and to try and prevent the aircraft from leaving the right side of the runway. The PF had probably already executed rolling take-offs when not yet lined up with the runway centre line, but in heavier aircraft.”
It was further noted that whilst the aircraft was travelling on the grass, “the PF reduced the speed of the left engine for a few seconds by moving the left engine throttle lever into the IDLE position and kept turning the manual nose gear steering wheel and depressing the left rudder pedal” and concluded that “these actions and the efficiency of the rudder” had enabled him to put the aircraft on a track which was convergent with the runway centre line. It was observed that the damage to the right engine had occurred whilst the aircraft was on the grass with the engine set to take-off thrust.
In respect of the continued take off, it was considered that “Crew Resource Management does not seem to have prompted the crew to carry out a better analysis of the situation or to take appropriate decisions.”
The formally recorded Conclusion of the Investigation was as follows:
“The runway excursion was due to non-compliance with the rolling take-off procedure, owing to the premature selection of the take-off thrust whilst the aircraft, which was light and had a centre of gravity to the rear, had not yet entered the runway.
A possible tendency on the part of the PF to select the thrust before the aircraft is fully lined up with the runway centre line contributed to this serious incident.
The decision to continue the take-off, after rejoining the runway at a speed below V1, prompted the crew to continue the flight despite the fact that they were unaware of the extent of the damage to their aircraft.”
The Final Report of the Investigation was issued in a French language version only in December 2010 and is also available here on SKYbrary in an [unofficial English language translation]. No Safety Recommendations were made.