WS131 - Incident: Westjet B737 near Vancouver on Mar 2nd 2024

A Westjet Boeing 737-700, registration C-FWCN performing flight WS-131 from Calgary,AB to Vancouver,BC (Canada) with 88 people on board, was enroute at FL320 about 45 minutes prior to estimated arrival, when the crew donned their oxygen masks and initiated an emergency descent to 10,000 feet due to the loss of cabin pressure. The aircraft continued to Vancouver for a safe landing on runway 08L about 45 minutes after leaving FL320.

The Canadian TSB reported:

During cruise at flight level 320 (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 4 000 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.

Related Flight: WS131, WestJet News