Loss of pressurization Incident Boeing 737-7CT (WL) C-FWCN, Saturday 2 March 2024
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Date:Saturday 2 March 2024
Time:22:30 PST
Type:Silhouette image of generic B737 model; specific model in this crash may look slightly different    
Boeing 737-7CT (WL)
Owner/operator:Westjet Airlines
Registration: C-FWCN
MSN: 33698/1346
Year of manufacture:2003
Fatalities:Fatalities: 0 / Occupants: 88
Other fatalities:0
Aircraft damage: None
Location:188 nm NE of Vancouver, BC -   Canada
Phase: En route
Nature:Passenger - Scheduled
Departure airport:Calgary International Airport, AB (YYC/CYYC)
Destination airport:Vancouver International Airport, BC (YVR/CYVR)
Investigating agency: TSB
Confidence Rating: Information verified through data from accident investigation authorities
WestJet Airlines flight WJA131, a Boeing 737-700 sufferered a loss of cabin pressure during cruise at FL 320.
Approximately 45 minutes prior to landing, the Captain felt sudden ear pressure and observed the cabin vertical speed indicator (VSI) was indicating a climb at the maximum rate position of 4000 feet per minute. The Captain donned his oxygen mask, declared a MAYDAY, and requested an immediate descent with air traffic control. The Cabin Altitude Warning horn sounded and the oxygen masks in the cabin deployed. The pilots referred to the quick reference checklist (QRC) and initiated the procedures outlined in the Cabin Altitude Warning checklist. During the rapid descent the flight crew were able to regain control of the cabin pressure in manual mode on the mode controller. When the crew completed the emergency descent and the aircraft was level at 10 000 feet above sea level (ASL), they removed their masks and checked on the cabin crew members and the passengers. The aircraft continued at 10 000 feet ASL until they descended for CYVR. Concurrently, approximately 20 minutes before the landing, the cabin crew heard a smoke detector alarm sound in the right aft lavatory. The cabin crew investigated and did not observe any smoke or fire. The aircraft landed without further incident. Aircraft rescue and firefighting crews met the aircraft and after a brief inspection, the crew taxied to the gate. There were no reported injuries and no damage to the aircraft.

Maintenance was unable to pressurize the aircraft the day after the occurrence. The air conditioning accessory unit was found to have failed and was replaced. An air check valve was also replaced. Following engine bleed system check and a successful flight test, the aircraft was returned to service. A Service Difficulty Report (SDR) is being prepared for submission to Transport Canada.


TSB A24P0026

Revision history:

19-Mar-2024 16:52 ASN Added

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