Blunder led to TUI 737 flight being aborted in mid air
An investigation revealed that a TUI aircraft carrying 193 passengers did not maintain cabin pressure because engineers neglected to reactivate switches after completing maintenance work.
On October 17, 2023, a Boeing 737-8K5 departed from Manchester Airport heading to Kos, Greece. However, it was forced to turn back just after reaching northern Lincolnshire.
The Air Accidents Investigation Branch (AAIB) discovered that both pilots missed the mistake during their inspections and did not follow the required procedures when it was brought to their attention.
The plane made its way back to Manchester without any reported injuries. However, investigators suggested that those onboard probably faced a growing risk of hypoxia. The BBC has reached out to TUI for their response.
Only three days later, the same plane went off the runway at Leeds Bradford Airport while Storm Babet was hitting the area. It was determined that a "catastrophic failure" of the nosewheel bearing was responsible for the incident.
A report about the incident in Lincolnshire revealed that the aircraft took off without the engine bleed air system turned on. This happened because the switches had been mistakenly left off after maintenance work was done the night before.
The switches were not activated during the pre-flight inspections either.
"The after take-off checklist is meant to catch such mistakes, but the crew failed to notice the wrong switch was chosen," the report indicates.
The engineer who performed the task informed AAIB investigators that they believed the switches were switched back to the "on" position after finishing the job.
Another engineer also did not notice the wrong position of the switch.
According to the report, the plane was unable to pressurize properly, and the crew did not follow the recommended procedures from the Quick Reaction Handbook (QRH) when they received a warning about the cabin altitude. This warning stayed on for 43 minutes.
A QRH (Quick Reference Handbook) features checklists that outline procedures for handling unusual situations. For instance, the cabin altitude checklist instructs on the prompt use of oxygen masks.
The report indicates that the pilot engaged both switches and proceeded to ascend.
Another alert went off, causing the pilot to halt the ascent and consult with the ground team.
The report indicates that the choice was made to head back to Manchester Airport, and the circumstances were communicated to the passengers through the loudspeaker system.
Investigators mentioned that if the plane, which had six crew members and 187 passengers on board, had kept ascending, the oxygen masks for the passengers would have activated automatically when the altitude reached 14,000 feet (4,267 meters).
According to the report, the chances of losing consciousness at altitudes under 14,000 feet are "extremely low" for individuals who do not have serious medical issues.
Nonetheless, it notes that this elevation might influence cognitive abilities and the process of making decisions.
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