Passengers were placed at risk of a deadly condition
A TUI flight suffered a ‘serious incident’ while carrying 187 passengers and six crew members en route to Kos Airport.
The Boeing 737-8K5 took off from Manchester Airport at 6.06am on October 17, 2023.
However, a new report from the Air Accidents Investigation Branch states that a cabin altitude warning alerted staff to a “serious incident” just minutes into the flight.
“Both engine bleed air systems had been inadvertently left off for the departure, so the aircraft failed to pressurise,” the report says.
Maintenance workers had reportedly turned the systems off for routine maintenance, but they failed to turn them back on.
Staff reactivated the systems and believed they had solved the issue, but this was not the case.
It’s reported that as the aircraft gained altitude the master caution lit, indicating a fault in the aircraft’s right air conditioning pack.
After consulting with maintenance control, it was concluded by the commander that the flight should return to Manchester.
However, the plane was too heavy to land, and so was placed in a holding pattern to burn fuel before landing.
The report claims that it was at this time crew failed to undertake necessary cabin altitude drills.
The oxygen mask light was lit for 43 minutes, leaving everyone onboard “exposed to the risk of hypoxia”.
Hypoxia is a dangerous condition where humans are deprived of oxygen. It can be fatal.
Investigators found that the “altitude window” caused “hypoxic exposure” that was significant enough to potentially affect cognitive performance.
“As the aircraft did not pressurise, the crew and passengers were exposed to the risk of hypoxia,” the report states.
“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.”
Thankfully, the plane landed safely at Manchester Airport at 8.10am.
The report says that the commander was running on three hours of sleep.
“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.”
The same plane ‘suffered a catastrophic failure’ just three days after the Manchester incident.
In an unrelated event, the plane landed at Leeds Bradford Airport during Storm Babet.
