Easyjet A20N near Belfast on Apr 20th 2025, loss of cabin pressure

Last Update: January 8, 2026 / 17:02:20 GMT/Zulu time

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Incident Facts

Date of incident
Apr 20, 2025

Classification
Incident

Cause
Loss of cabin pressure

Airline
Easyjet

Flight number
U2-3011

Departure
Belfast Aldergrove, United Kingdom

Destination
Palma Mallorca, Spain

Aircraft Registration
G-UZEF

Aircraft Type
Airbus A320-200N

ICAO Type Designator
A20N

An Easyjet Airbus A320-200N, registration G-UZEF performing flight U2-3011 from Belfast Aldergrove,NI (UK) to Palma Mallorca,SP (Spain) with 177 passengers and 6 crew, was enroute at FL390 about 140nm south of Belfast when the crew initiated an emergency descent due to the loss of cabin pressure. The aircraft subsequently levelled off at FL200 and about 6 minutes later climbed back to FL370 and continued to Palma Mallorca for a safe landing.

The aircraft departed for the return flight with a delay of about 3 hours and continued service.

The AAIB rated the occurrence a serious incident and opened an investigation.

On Jan 8th 2026 the AAIB released their bulletin concluding the probable cause of the serious incident was:

The event was caused by missing checklist items that were not noticed by either crew until the cabin altitude reached the threshold for the aircraft system alerts. The crew managed the event successfully, getting the aircraft into a descent before the situation in the cabin required the passengers to use oxygen masks. Once the error was detected and rectified, the crew reviewed their situation and concluded that it was appropriate to continue to their destination.

The AAIB summarized the sequence of events:

The crew left the ditching pushbutton selected when re-configuring the aircraft from the de-icing checklist. With the ditching pushbutton selected the aircraft did not pressurise and the cabin altitude slowly increased as the aircraft climbed to its cruise altitude of FL390. The crew were alerted to the increasing cabin altitude, and an emergency descent was performed. During this procedure the commander noticed the ditching pushbutton was on and once this was deselected the aircraft pressurisation returned to normal. The aircraft was levelled at FL200 and after some analysis the crew determined that they could continue with the flight to their destination. The aircraft climbed up to FL370 and the rest of the flight was completed without further incident.

The AAIB analysed:

After configuring the aircraft for de-icing, which was then not required, the crew re-configured the aircraft, but did not deselect the ditching pushbutton or check that the outflow valve was open, as required by the checklist. The commander, who was PM for the flight, performed the configuration as ‘read and do’ with the co-pilot watching. The co-pilot, who was under training, had never performed the de-icing procedure before, and the checklist was unfamiliar. The commander felt some time pressure to get the aircraft away as close to scheduled time as possible and, as a result, probably completed the re-configuration with little reference to the checklist. The unusual situation of the eventual lack of de-icing also meant that several of the items on the checklist were not relevant and were skipped. With the dark light conditions, the flight deck annunciator lights had been set to dim. That, together with the ditching pushbutton being difficult to see from the left seat, meant the commander did not notice it was illuminated until after the emergency descent had been initiated, when he switched the annunciator lights to bright.

Selecting the ditching pushbutton signals the pack control valves to close regardless of the pack and engine bleed selections. That meant there was no air flowing into the packs which normally provide air for pressurisation of the cabin. As the aircraft climbed, the pressure in the cabin slowly reduced as the air leaked out. Eventually, as the aircraft reached FL390, the ECAM alerted the crew to the pressurisation problem.

Having noticed the cabin altitude continuing to rise, but without an identifiable reason for it, the commander instructed that they should both go onto oxygen and initiate an emergency descent. The descent was well managed as a crew, with the commander taking over when he felt the co-pilot hesitated, and the co-pilot providing good support once he had become PM. During the descent, the commander switched the annunciator lights to bright and noticed the illuminated ditching pushbutton. De-selecting the button saw the aircraft immediately begin to pressurise. The commander levelled the aircraft at FL200 where the crew discussed their options using the operator’s decision-making framework. They concluded that they could continue to their destination, so climbed up to FL370 and continued the flight without further incident.

The operator had recorded 19 previous events, where the ditching pushbutton had not been deselected, but all of those occurred on the ground. A number of those reports noted difficulty in seeing the ditching pushbutton from the left seat. The manufacturer recorded six events where ECAM alerts were generated in flight because of the ditching pushbutton being on. Four of those involved incorrect reconfiguration after de-icing, with the other two having insufficient information to tell.