A TUI plane with 187 passengers on board was involved in a 'serious incident' above North Lincolnshire just three days before the same plane had a 'catastrophic failure' in an unrelated incident.
The Boeing 737-8K5 took off from Manchester Airport at 6:06am on 17 October, 2023, and a report by the Air Accidents Investigation Branch (AAIB) has looked into what happened.
Just six minutes after takeoff, there was a cabin altitude warning when the aircraft travelled over North Lincolnshire, expecting to land at Kos Airport in Greece, the AAIB said.
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The report claims that 'both engine bleed air systems had been inadvertently left off for the departure' and that the plane was unable to 'pressurise'.
During pre-flight checks, both engines should have been turned on.
After spotting the issues, airline staff were able to successfully turn on both systems, but then another problem occurred when climbing mid air.
The master caution lit up and warned that there was a fault in the right air conditioning pack.
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To avoid any risk, the decision was made for the aircraft to return to Manchester Airport.
"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," the report said.
"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."
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The report states that 'the aircraft’s passenger oxygen system would have deployed automatically when the cabin altitude reached 14,000 ft'.
It added: "As progressive exposure to hypoxia increased, the likelihood of the crew taking correct recovery actions would have decreased."
Suggestions were also made that the commander only had three hours of sleep the previous night and 'had carried out a significant number of overtime duties' over the previous weeks.
"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," it said.
Thankfully the TUI aircraft landed safely at Manchester Airport at 8:10am and nobody was injured.
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Though just three days later on 20 October, the same plane 'suffered a catastrophic failure' during an unrelated incident after troubling weather conditions from Storm Babet meant the jet was forced to land at Leeds Bradford Airport. No one was injured.
LADbible Group has contacted TUI for comment.
Anish Vij