What happened
On 11 December 2018, an Embraer 190-100 SR, registration G-LCYZ, was performing a commercial passenger flight from London City Airport. During the takeoff roll, as the aircraft accelerated through 60 knots, the crew noticed that the Engine Indicating and Crew Alerting System (EICAS) was displaying a 'Takeoff 3' (T/O-3) thrust indication. The flight had been planned using a 'Takeoff 1' (T/O-1) setting, which provides higher maximum available thrust.
The T/O-3 setting reduced the maximum available thrust per engine from 18,500 lbf to 15,450 lbf. The commander, acting as Pilot Monitoring, determined that continuing the takeoff was safer than attempting to reject it, as the incorrect setting had invalidated the previously calculated rejected takeoff stopping distances. To compensate for the reduced power, the commander delayed the rotation call by approximately 5 knots. The aircraft climbed out without further incident, though a subsequent recalculation above 10,000 feet indicated that while a safe stop was possible up to V1, climb performance could have been compromised had an engine failure occurred shortly after liftoff.
The investigation
The AAIB investigation established that the takeoff performance figures had been correctly calculated using electronic flight bags, but the T/O-3 setting was manually entered into the flight management computer in error. The crew could not confirm if the incorrect setting was read out incorrectly or misheard during the Vital Data Review (VDR).
Investigators examined the aircraft's systems and found that while the aircraft featured an Automatic Takeoff Thrust Control System (ATTCS) to increase thrust to a reserve level during an engine failure, the crew did not consider that advancing the thrust levers to command this reserve thrust was necessary for a safe departure. The investigation also noted that the aircraft lacked any automated system to alert pilots to an inappropriate takeoff thrust setting.
Findings
- The T/O-3 thrust setting was manually selected in error during cockpit preparation.
- Human performance limitations and potential confirmation bias contributed to the error remaining undetected during the pre-takeoff checks.
- The commander's recent experience primarily flying the smaller E170 variant, which frequently utilizes the T/O-3 de-rate, may have contributed to the initial slip.
- The reduced thrust setting could have adversely affected aircraft handling and performance in the event of an engine failure during the initial climb.