A Boeing 737 carrying 185 passengers struggled to take off before it reached the end of the runway at Belfast International Airport last year after pilots typed the wrong temperature into the onboard computer, which investigators said could have had "catastrophic" consequences.
With the autopilot calculating the takeoff speed based on a temperature of -52 degrees, instead of 16 degrees, the plane lifted off at the extreme end of the runway, striking a 36cm-high light on the ground almost 30m after takeoff.
Pilots eventually increased the thrust after the 737 had travelled 2½ miles and climbed to just 800ft, far below the usual steep climb on takeoff.
Investigators said only the “benign nature” of the clearway after the runway, and the surrounding area’s lack of obstacles, saved the plane from further collision. They said any engine failure that might have occurred as the plane struggled to get off the ground would have been catastrophic.
The incident happened on a Sunwing holiday flight from Belfast to Corfu on July 21st last year. Crew on the Canadian carrier could not account for why they had put in the wrong temperature, but investigators found that one of the pilots may have been suffering from jetlag.
The crew did not report the incident themselves. They only became aware something was wrong with the acceleration as the aircraft was rapidly approaching the end of the runway. After applying the full thrust, the plane climbed and continued its flight to Greece safely.
Airport staff who had seen the low takeoff and checked the broken light found it marked with rubber from the 737’s tyre.
The Air Accidents Investigation Branch recommended that all Boeing 737s have a software upgrade, which had been available but not installed on the Sunwing flight, to ensure the plane crosschecks the information typed into the flight management system with its own temperature sensors.
It has also recommended that safety systems be introduced to warn pilots of unusually low acceleration before take-off, and low altitude afterwards. – Guardian