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| Date: | Monday 22 December 2008 |
| Time: | |
| Type: |  Airbus A319-111 |
| Owner/operator: | TAP Air Portugal |
| Registration: | CS-TTA |
| MSN: | 750 |
| Year of manufacture: | 1997 |
| Engine model: | CFMI CFM56-5B5/P |
| Fatalities: | Fatalities: 0 / Occupants: |
| Other fatalities: | 0 |
| Aircraft damage: | None |
| Category: | Incident |
| Location: | Waypoint RALUS -
 Portugal
|
| Phase: | En route |
| Nature: | Passenger - Scheduled |
| Departure airport: | København-Kastrup Airport (CPH/EKCH) |
| Lisboa-Humberto Delgado Airport (LIS/LPPT) | |
| Investigating agency: | GPIAA |
| Confidence Rating: |  Accident investigation report completed and information captured |
The aircraft was operating a flight from Copenhagen to Lisbon when, while cruising at flight level 390 and approaching waypoint RALUS - a point located on the boundary between the Spanish and Portuguese FIRs (Flight Information Regions) - a pressurization failure occurred.
The cabin pressurization system failed in both mode 1 and mode 2, and effective control of the outflow valve was unsuccessful when switched to MANUAL mode. In this manual mode, the cabin rate of climb/descent varied between a descent of 1000 feet per minute and a climb of 1600 feet per minute.
After the system failure, the pilots attempted to reset the Cabin Pressure Controllers (CPCs), but without success. The cabin altitude exceeded the safety threshold of 10,000 feet, reaching up to 10,800 feet.
The crew donned their full-face oxygen masks and declared a PAN PAN emergency to Madrid ATC. Since they received no response from Madrid Control, the pilots escalated to a MAYDAY MAYDAY declaration and initiated an emergency descent.
During the descent, due to TCAS detection of traffic below CS-TTA, the descent was temporarily halted at flight level 350, at which point the cabin altitude recovered to 9000 feet. The remaining descent was managed by Lisbon ATC, to whom the pilots canceled the emergency. The final phase of the flight, including landing at Lisbon International Airport, was completed without further incident.
The aircraft was handed over to the Operator’s Maintenance team, who discovered that the Outflow Valve (OFV) was inoperative, mechanically blocked, and not responding to CPC inputs or pilot commands in MANUAL mode.
Accident investigation:
 |
|
Sources:
GPIAAF
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 12-Apr-2025 09:55 | ASN | Added |
| 01-May-2025 15:37 | ASN | Updated [Cn, Location, Phase, Nature, Departure airport, Destination airport, Damage, Narrative, ] |
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