Incorrect weight data on an in-flight computer caused the tail of an Emirates Airbus A340 (A6-ERG) to scrape the runway during takeoff March 20, 2009 from the Melbourne Airport, according to Australian Transport Safety Board (ATSB) officials.
The Dubai-bound jetliner was forced to make an emergency landing an hour after taking off. Flight EK407 circled the airport for more than 30 minutes to dump fuel before landing safely. There were no injuries among the 257 passengers and 18 crewmembers on board, but plane’s tail was seriously damaged from being dragged along the tarmac.
The ATSB’s preliminary findings determined that during the takeoff roll on Runway 16, the captain called for the first officer to rotate. However, when the aircraft was slow to respond, the captain commanded and applied maximum take-off thrust. The aircraft’s tail struck the runway and the aircraft lifted off shortly afterwards. During the takeoff, the aircraft’s tail contacted the ground beyond the end of the runway and a number of airport landing aids came into contact with the aircraft.
After becoming airborne, the flight crew received a cockpit message that a tail strike had occurred. They contacted Air Traffic Control and requested a return to Melbourne. The aircraft was radar vectored over Port Philip Bay to dump fuel to reduce the aircraft’s weight for landing.
“While reviewing the aircraft’s performance documentation in preparation for landing, the crew noticed that an incorrect weight had been inadvertently entered into the laptop when completing the take-off performance calculation prior to departure. The performance calculations were based on a take-off weight that was 100 tons below the actual takeoff weight of the aircraft. The result of that incorrect takeoff weight was to produce a thrust setting and takeoff reference speeds that were lower than those required for the aircraft’s actual weight,” the ATSB report states.
The ATSB did not say how the wrong number came to be entered into the computer or why the crew failed to pick up the error in cross-checks.
During the return to land at Melbourne, a cabin crewmember reported smoke in the cabin. The aircraft subsequently landed safely and was able to be taxied to the terminal.
Damage to the aircraft included abraded skin to the rear, lower fuselage and damage to the rear pressure bulkhead. There was also damage to a fixed approach light, an instrument landing system (ILS) monitor antenna and the ILS localizer antenna.
The aircraft was fitted with a Flight Data Recorder (FDR), Cockpit Voice Recorder (CVR) and a Digital Aircraft Condition Monitoring System Recorder (DAR). The FDR was dislodged from its mounting in the rear of the aircraft during the tail strike and only recorded data up to that point. The CVR and DAR recorded data for the entire flight.
The ATSB said the accident investigation is continuing and will examine:
- human performance and organizational risk controls
- computer-based flight performance planning, including the effectiveness of the human interface of computer based planning tools.
- reduced power takeoffs, including the associated risks and how they are managed.
- The aircraft operator has informed the ATSB that based on their internal investigation, the following areas are under review:
- human factors
- training
- fleet technical and procedures
- hardware and software technology.
The Australian quotes the airline’s senior vice-president for flight operations, Alan Stealey, as saying the air carrier has a standard operating procedure for setting up the plane for takeoff. Stealey said the error should have been picked up.
“The process itself is extremely robust if it’s done correctly,” he said. “The process that we use is the same one that Airbus … have in their manuals and we’ve picked it up and we’ve operated with that.”
Emirates held its own board of inquiry into the accident. The results have not been released, but both pilots have since resigned from the company, the Australian newspaper reported.
He said the company has heard from a major avionics firm about developing some kind of performance monitor.
“And if we can work with them, we have sufficient leverage with both of the big manufacturers as an airline that we can actually drive the industry and get a solution not just for our own airline but across the industry itself,” he said.
“We believe there’s probably sufficient information on the aircraft itself to develop some kind of software to monitor the performance on takeoff, to warn the crew that the acceleration is not what would be expected under the circumstances.”