(File pic) A TUI passenger plane was flying above the Humber area when it was involved in a ‘serious incident’ (Image: Getty)
A TUI passenger plane was flying above the Humber area when it was involved in a “serious incident”, just three days before the same aircraft suffered an unrelated “catastrophic failure” while landing at Lees Bradford Airport, a report has found.
A new report released by the Air Accidents Investigation Branch looked into the North Lincolnshire incident. The Boeing 737-8K5 had taken off from Manchester Airport shortly after 6am on October 17 2023. It was carrying 187 passengers and six crew members – no one was injured in the incident. The aircraft landed safely at Manchester at 8.10am.
Just a few minutes after take off, a cabin altitude warning alerted the pilot of a cabin pressure failure while flying to Kos Airport in Greece.
The “serious incident” report said: “Both engine bleed air systems had been inadvertently left off for the departure, so the aircraft failed to pressurise.”
Engineers had reportedly let off the systems during previous maintenance, yet not turned back on during the plane’s pre-flight checks.
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An investigation took place into the aircraft which had two serious incidents just days apart (Image: Getty)
The crew selected both systems to be back on and, believing the problem was solved, continued to fly higher into the sky. However, during the climb, the master caution lit up, which indicates a fault. The commander decided to return back to Manchester Airport as a safety precaution after consulting the operator’s maintenance control.
Since the plane was too heavy to land, it had to enter a hold to burn fuel and reduce the aircraft’s weight. The crew did not complete the prescribed drills specific to them in response to a cabin altitude warning – such as wearing oxygen masks – which remained illuminated for 43 minutes, reports.
The report described the risk of hypoxia, low levels of oxygen in the blood, saying: “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.
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“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 aircraft’s climb was interrupted by the air conditioning caution, the report said. It said that, had the aircraft continued to climb, “the aircraft’s passenger oxygen system would have deployed automatically when the cabin altitude reached 14,000 ft”.
Once reaching 15,800 ft cabin altitude, the pressurisation auto fail master caution would have been triggered. The report added: “As progressive exposure to hypoxia increased, the likelihood of the crew taking correct recovery actions would have decreased.”
The report also noted that the pilots were not originally scheduled to fly that plane, stepping up from standby duty at 3am. The commander, who had been woken up by a notification on his smartphone roster app at 1am indicating he had been assigned to the Manchester to Kos flight, had reportedly only slept for three hours the previous night, having carried out a “significant number of overtime duties” over the previous eight weeks.
The co-pilot was notified by a phone call from crewing at 2.30am. Both pilots were given a report time of 4.30am.
Although they were not necessarily individually fatiguing, the cumulative disruption may have been a factor, the report stated. It read: “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.”
Three days after this incident, the same aircraft left the runway while landing in the midst of Storm Babet at Leeds Bradford Airport. While the aircraft sustained minor damage, none of the people on board were injured.
TUI was approached for comment.