Catastrophe averted: Canadian Sunwing Boeing 737 from Belfast could barely take off after data error
- The plane carrying 185 passengers almost ran out of runway, clipped a 36cm-tall light, then only reached an altitude of 240 metres, 4km after take-off
- Only a lack of obstacles prevented a disaster, after the pilots for the Canadian airline inadvertently input the wrong air temperature
A Boeing 737 carrying 185 passengers struggled to take off before it reached the end of the runway at Belfast international airport and then flew low for 4km (2.5 miles) after pilots typed the wrong temperature into the on-board computer, which investigators said could have had “catastrophic” consequences.
With the autopilot calculating the take-off speed based on a temperature of -52C, instead of 16C, the plane lifted off at the extreme end of the runway, striking a 36cm-high (1.2-foot) light on the ground almost 30 metres (33 yards) after the end of the runway.
Pilots eventually increased the thrust after the 737 had travelled 4km and climbed to just 240 metres (787 feet), far below the usual steep climb on take-off.
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 21 last year. The UK’s Air Accidents Investigation Branch issued a report on the event Wednesday.
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 jet lag.
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 take-off 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 cross checks 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.