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| Date: | Tuesday 11 December 1990 |
| Time: | 06:30 |
| Type: |  Lockheed L-1011-385-3 TriStar 500 |
| Owner/operator: | Air Canada |
| Registration: | C-GAGI |
| MSN: | 193H-1209 |
| Fatalities: | Fatalities: 0 / Occupants: 114 |
| Other fatalities: | 0 |
| Aircraft damage: | Substantial |
| Category: | Accident |
| Location: | 1NM Southeast of Manchester -
 United Kingdom
|
| Phase: | En route |
| Nature: | Passenger - Scheduled |
| Departure airport: | Montréal-Pierre Elliot Trudeau Airport, QC (YUL/CYUL) |
| London-Heathrow Airport (LHR/EGLL) | |
| Investigating agency: | AAIB |
| Confidence Rating: |  Accident investigation report completed and information captured |
The aircraft was operating schedule Air Canada 866 from Montreal Mirabel to London Heathrow.
Shortly after passing Manchester at flight level (FL) 370 the aircraft suffered a rapid loss of cabin pressurisation and a few seconds later the cabin altitude warning horn sounded. The crew donned oxygen masks and the first officer obtained clearance to descend. The commander began a maximum rate descent whilst the second officer completed the checklist for an emergency descent and confirmed the automatic deployment of the passenger oxygen masks. Having advised ATC that the aircraft had a pressurisation problem, the first officer then declared an emergency and was given unrestricted clearance for both altitude and heading. He then switched on the 'Fasten Seat Belts' sign and broadcast on the cabin address system an instruction to the passengers to put on oxygen masks immediately, repeating these words twice. In the passenger cabin, two flight attendants near the rear of the aircraft heard a dull 'boom' and a sound of rushing air from the left-hand rear toilet. Some 30 to 40 seconds later the flight attendants saw the passenger oxygen masks deploy. All then took their seats and donned masks in accordance with their standard operating instructions. The commander meantime had established the aircraft in descent at maximum operating speed (Mudmo), descending to FL180 in a little over 3 minutes. He continued down to FL100 at a slightly reduced rate of descent, reaching this level some 5 minutes 20 seconds after cabin pressurisation was lost. During the descent, cabin altitude rose rapidly from 6,300 feet to a peak of 20,500 feet before falling again quickly to 10,000 feet. Cabin altitude was above 20,000 for 56 seconds and above 18,000 for 2 minutes 20 seconds. When the aircraft was level at FL100 the commander used the cabin address to call the in-charge flight attendant to the cockpit, who advised him that the passengers were in a satisfactory condition. On hearing this call on the cabin address, the flight attendants left their seats and continued their normal duties. They found that during the emergency 3 passengers had experienced severe headache and earache. A few others complained of dizziness. The aircraft made a normal landing at London Heathrow at 0658 hrs. After landing, an inspection of the aft toilet compartments revealed that one of the decorative wall panels had been pushed back towards the rear pressure
bulkhead, causing the corners of the panel to split. Fibreglass insulation material was hanging from access panel grills on the fuselage skin beneath the tailplane centre section, and additional insulation could be seen distributed around the interior of the rear fuselage aft of the rear pressure bulkhead. An inspection of the aft side of the rear pressure bulkhead revealed that it had ruptured near the outer edge of the 8- 9 o'clock gore panel, allowing a rectangular element approximately 2ft high by 1ft wide to flap outwards.
Accident investigation:
 |
|
Sources:
https://assets.publishing.service.gov.uk/media/5422f44ced915d13740004c7/3-1991_C-GAGI.pdf
https://www.jetphotos.com/photo/7664818 (Photo)
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 09-Mar-2025 07:55 | Justanormalperson | Added |
| 09-Mar-2025 07:56 | ASN | Updated [Narrative, Accident report, ] |
| 09-Mar-2025 07:57 | ASN | Updated |
| 24-May-2025 15:02 | Justanormalperson | Updated |
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