LONDON (Reuters) - A small business jet narrowly missed colliding with a Boeing 777 carrying 232 people over the capital this summer because of a verbal communication error, air accident investigators said on Thursday.
The jet came perilously close to flying into the path of a Turkish Airlines passenger plane after taking off from London City Airport, as the 777 began its descent into the city’s larger Heathrow airport.
Describing the near-miss in late July as a “serious incident,” the Air Accidents Investigation Board (AAIB) said the planes came within half a mile of each other.
The business jet, carrying two crew and one passenger, was flying only 100 feet (30 metres) to 200 feet below the descending airliner, the AAIB said.
Investigators said a communication error between the pilot of the smaller jet and air traffic controllers at London City Airport had caused it to stray into the 777’s flight path. Controllers had given the business jet clearance to climb to 3,000 feet, but when the flight crew relayed back the instruction, as required, they mistakenly said 4,000 feet instead.
The voice error was not picked up by the tower and the Turkish flight had descended to the same altitude.
The AAIB said if the incident had happened during bad weather the only barrier to a potential mid-air collision would have been to use a collision-avoidance system on the airliner as the respective pilots would not have seen each other.
Investigators said the Turkish Airlines flight crew had not noticed the on-board collision-avoidance warnings, while the smaller jet was not fitted with the specialised equipment.
Writing by Stefano Ambrogi; Editing by Steve Addison