Investigation Summary
The investigation focused on the ergonomics of the Electronic Flight Bag (EFB) and the human factors of data entry. The crew intended to use a takeoff weight of 362.9 tonnes, but the first officer typed 262.9 tonnes. This 100-tonne discrepancy led the EFB to calculate a 'flex' temperature and V-speeds that were dangerously low for the aircraft's actual mass. Because the pilots flew a 'mixed fleet' (both A330 and A340), they were accustomed to a wide range of weights, which degraded their ability to recognize that the calculated speeds were 'unreasonable' for a fully loaded A340-500. The error was compounded by distractions in the cockpit during the pre-flight phase, which caused the crew to skip verbal cross-checks that might have caught the typo.
Final Conclusions
The Australian Transport Safety Bureau (ATSB) concluded that the primary cause was a transcription error during the takeoff performance calculation. The crew's failure to detect the 100-tonne error was attributed to cockpit distractions, non-adherence to standard operating procedures regarding verbal verification, and the lack of an automated system to cross-check EFB inputs against the aircraft's actual weight. The aircraft's survival was credited to the captain's rapid decision to apply TOGA thrust, though the aircraft still came within meters of impacting the airport perimeter fence.
Video Analysis
100 Tons Too Light: The Near-Disaster of Emirates 407 — On March 20, 2009, an Airbus A340-541 attempted takeoff from Melbourne’s Tullamarine Airport. Due to a miscalculated weight entry, the takeoff turned into a battle to get the massive aircraft into the air.
If playback is blocked, the owner has disabled embedding — use the link above.
Airframe & Maintenance
Crew Experience
Captain
First Officer
Relief Captain
Relief First Officer
Systems & Failure Modes
Electronic Flight Bag (EFB)
The laptop-based system used by the crew to calculate takeoff performance; it lacked a 'reasonableness' check for weight inputs.
Takeoff/Go-Around (TOGA) Detent
The maximum thrust setting applied by the captain to force the aircraft into the air after the initial rotation failed.
Flight Management and Guidance System (FMGS)
The onboard computer where the erroneous EFB speeds were manually entered, failing to trigger an alert despite the weight discrepancy.
Interesting Facts
- 01The aircraft was 100 tonnes heavier than the weight used for takeoff calculations (362.9t actual vs 262.9t entered).
- 02The tail struck the runway three times during the takeoff roll, causing substantial structural damage.
- 03The aircraft cleared the airport perimeter fence by only a few feet.
- 04The impact with the localizer antenna disabled the Instrument Landing System (ILS) for Runway 16.
- 05Both pilots resigned from Emirates shortly after the incident.
Safety Actions & Advisories
Software Enhancements
Emirates and Airbus reviewed the human factors of data entry, leading to software updates in Electronic Flight Bags to include 'reasonableness' checks or automated alerts when entered weights differ significantly from the aircraft's sensed weight.
Takeoff Performance Monitoring Systems
The accident accelerated the development and implementation of onboard systems designed to monitor real-time acceleration and alert pilots if the aircraft is not performing according to the calculated parameters.