A potential disaster was narrowly avoided when a loaded passenger plane took off just seconds before it was about to veer off the runway due to a software glitch.
The Boeing jet, operated by TUI, was flying from Bristol Airport to Las Palmas in Gran Canaria on March 9 with 163 passengers on board when it had difficulty taking off.
The 737-800 cleared runway 9 with only 260 meters (853 ft) of tarmac remaining at 10 feet.
It then flew over the nearby A38 at a height of only 30 meters (100 ft), traveling at about 150 kts (about 173 mph).
The A38 is a major busy A-class road linking the South West of England with the Midlands and the North.
The Air Accidents Investigation Branch (AAIB), part of the Department for Transport, said the incident was the result of insufficient thrust being used during take-off.
The pilots manually adjusted the thrust level after a software glitch that Boeing was aware of before takeoff.
“The Boeing 737-800 completed take-off from runway 09 at Bristol Airport with insufficient thrust to meet regulated performance,” the AAIB report said.
“The automatic throttle (A/T) disengaged when the takeoff mode was selected, early in the roll-off, and subsequently the crew’s manually set thrust (84.5% N1 ) was less than the required takeoff thrust (92.8% N1 ). .
“Neither pilot noticed that the thrust was set incorrectly and was not caught by standard operating procedures (SOPs).
The plane’s acceleration was significantly slower than 99.7 per cent of other planes of the same model departing from the same airport, performance data collected by the AAIB showed.
The autothrottle system on the Boeing 737-800 can control thrust from take-off to landing, the AAIB added.
Boeing told investigators looking into the incident that it was aware of “a long history of nuisance disconnects during takeoff mode engagement.”
She added that the plane was equipped with an FDR recording device, known as a “black box”, which records flight data, and a CVR, which records recent sounds in the cockpit.
The AAIB said: “G-FDZS was equipped with both FDR and CVR. The CVR fitted to G-FDZS was not removed from the aircraft as it is constantly overwritten and only retains the last two hours of audio.
“The take-off recording would thus be overwritten during the flight to Las Palmas. However, FDR was removed and withdrawn”.
The incident is the latest in a series of problems with Boeings in recent years.
The aviation giant’s safety standards are coming under increasing scrutiny after several incidents recent incidentsincluding one where an unused door fell out of a brand new 737 Max shortly after takeoff. There were no injuries.
In April, a FedEx Airlines Boeing cargo plane landed at Istanbul Airport without its nose gear deployed, but managed to stay on the runway.
Five years ago, Boeing pledged to pay $2.5 billion and then make safety improvements two new 737 Max jets crashed over five months – one in Indonesia in 2018 and one in Ethiopia in 2019, killing a total of 346 people.
In May, US officials warned Boeing that it could face criminal prosecution following claims the airline failed to improve aircraft safety and honor the agreement following the fatal 737 crashes.
A TUI UK&I spokesman said: “We have been working closely with the authorities to provide all available information.
“The AAIB’s recommendations and insights from this launch will support the entire aviation sector and other airlines. The safety of our passengers and crew is always our top priority.”
Boeing has been contacted for comment.