Almost 200 people were left at risk of developing a potentially fatal condition after a “serious incident” in the skies above a UK airport. A TUI plane had to return to Manchester Airport in October last year after an alert following takeoff.
Just minutes into the Boeing 737-8K5’s flight to Kos Airport in Greece, shortly after 6am on October 17, 2023, a cabin altitude warning was sounded, according to a report from the Air Accidents Investigation Branch.
The alert informed the six crew members that two vital systems were turned off, Grimsby Live reports. The report said: “Both engine bleed air systems had been inadvertently left off for the departure, so the aircraft failed to pressurise.”
The crew reactivated the systems, which had been turned off by engineers performing routine maintenance and not turned back on. They believed the problem was then solved but then soon hit another issue.
As the TUI aircraft continued to climb, the master caution lit up, highlighting a fault in the plane’s right air conditioning pack. After consulting the operator’s maintenance control, the commander concluded that the plane should return to Manchester Airport.
However, the aircraft was too heavy and the pilot was forced to keep it in the sky, entering a holding pattern and burning fuel before landing. The report states that during this time, the crew failed to complete the necessary cabin altitude drills with the 187 passengers.
The oxygen mask light remained illuminated for around 43 minutes while crew and passengers were left “exposed to the risk of hypoxia” – a dangerous and potentially fatal condition where the body is deprived of oxygen.
The report found that, at that time, the “altitude window” caused “hypoxic exposure” significant enough that it could have noticeably affected people’s cognitive performance. It concluded: “As the aircraft did not pressurise, the crew and passengers were exposed to the risk of hypoxia. At cabin altitudes above 10,000 ft but below 14,000 ft, without the pre-existence of significant medical issues, the likelihood of loss of consciousness is very small.
“However, in this altitude window, the hypoxic exposure can be sufficient to affect cognitive performance and decision-making to the point where the decline would be observable in cognitive tests.
“In this range of altitudes there are many variables that affect the severity and impact of hypoxia, including duration of exposure, rate of hypoxia onset (eg rate of climb if no pressurisation), physical workload, fatigue, individual responses and type of task being performed.
“In this range of altitudes it is also difficult to separate the relative contribution of hypoxia versus other performance degraders such as fatigue, distraction or other human performance issues.”
The plane ultimately landed safely and without incident at Manchester Airport at 8.10am after completing its holding pattern. The report later states the commander was operating on three hours of sleep.
The report added: “Though the commander did not believe fatigue was a factor in this event, the analysis of his roster over the eight weeks preceding the event and the rest period immediately before it suggest that fatigue could still have been a contributory factor. It should be noted that fatigue, particularly chronic fatigue, can be insidious such that an individual may not recognise the symptoms in themselves.”
TUI has been approached for comment.
Don’t miss the latest news from around Scotland and beyond.Sign up to our daily newsletter.