Loss of pressurization Serious incident Boeing 737-8GQ (WL) OK-TSO, Wednesday 14 June 2023
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Date:Wednesday 14 June 2023
Time:08:45 UTC
Type:Silhouette image of generic B738 model; specific model in this crash may look slightly different    
Boeing 737-8GQ (WL)
Registration: OK-TSO
MSN: 35793/2428
Year of manufacture:2007
Fatalities:Fatalities: 0 / Occupants: 128
Other fatalities:0
Aircraft damage: None
Category:Serious incident
Location:N of Chania -   Greece
Phase: En route
Nature:Passenger - Scheduled
Departure airport:Chania-Soúda Airport (CHQ/LGSA)
Destination airport:Praha-Václav Havel Airport (PRG/LKPR)
Investigating agency: UZPLN
Confidence Rating: Information verified through data from accident investigation authorities
Smartwings flight QS1111, a Boeing 737-8GQ, suffered a loss of cabin pressure about 12 minutes after takeoff from Chania-Soúda Airport (CHQ).
The flight crew initiated an emergency descent and diverted to Heraklion, Crete.

Prior to departude from Chania, maintenance was conducted on the aircraft due to a fault message "ENGINE COWL VALVE OPEN" on the right engine. The aircraft was released by a Greek technician based on MEL 30-03-03B.
During engine start-up, the crew noticed low pressure in the air supply of the right engine. After consulting with MCC, the crew decided to proceed with taxiing for takeoff.
At FL230, a cabin altitude warning sounded, and the crew immediately donned oxygen masks and initiated appropriate procedures. The crew decided to descend immediately to FL100. Attempts to establish communication with ATC were unsuccessful due to frequency congestion, so the crew set the SSR transponder code to 7700 and initiated an immediate descent.
Shortly after, the crew established communication with ATC and declared an emergency and descent to FL100.
During the descent, cabin altitude continued to rise. The pilots consulted with the cabin manager about the passengers' condition and decided to manually activate passenger oxygen masks.
The crew then opted for diversion to LGIR (Heraklion).
Upon reaching FL80, the crew removed their oxygen masks and informed the cabin crew and passengers about the situation and diversion.
The crew canceled the emergency status and informed the operations center in Prague.
During the approach, the crew gradually released pressure from the aircraft. Despite careful manipulation of the pressurization valve, there were significant changes in cabin altitude ±1,000 ft.
The landing was completed without further complications.

In the service organization at Heraklion Airport, it was discovered that the maintenance at Chania Airport was not carried out in accordance with the procedures specified in MEL 30-03-03B. There was incorrect handling of the valves controlling the aircraft's pressurization system.
The aircraft was released by the service organization at Heraklion Airport for a technical flight without passengers to Prague.



Revision history:

15-Jun-2023 19:15 harro Added
15-Jun-2023 19:15 harro Updated
22-Jul-2023 07:19 harro Updated

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