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A Q400 flight crew failed to note the pack switches were in the off position which caused a cabin altitude warning on the subsequent climb out. The switches were repositioned; pressurization resumed and the flight continued to its destination.
| Attributes | |
| ACN | 867432 |
| Time | |
| Date | 201001 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | Q400 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Climb |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Air Conditioning and Pressurization Pack |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Person 2 | |
| Function | Pilot Not Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy |
Narrative:
Climbing through 12;000 a triple chime master warning was followed by a cabin altitude warning. We complied with the emergency checklist while obtaining a descent clearance from ATC. We found both of the pack switches in the off position. After turning on the pack switches; the aircraft began pressurizing normally and the flight continued to destination. Neither I; nor the first officer recalled turning the pack switches off; it would be unusual for any crew member to touch those switches; and they were obviously on when I had landed the leg before because I had brought the same aircraft in. I did have a different first officer for that flight. Because it was not a new aircraft for me; I did not 'originate' the aircraft where I would have checked the pack switch position. It is possible that the previous first officer accidentally turned off the pack switches instead of the bleed switches on the previous parking flow; or that somehow the switches were accidentally turned off by either of us in the course of attempting to complete our flows. It is a poor design feature of the Q400 that there is no cockpit annunciation of the pressurization air flow being turned off. Also; it would be helpful if the after start flow had the crew check that the pack switches are on; along with the bleed switches.
Original NASA ASRS Text
Title: A Q400 flight crew failed to note the pack switches were in the OFF position which caused a cabin altitude warning on the subsequent climb out. The switches were repositioned; pressurization resumed and the flight continued to its destination.
Narrative: Climbing through 12;000 a triple chime master warning was followed by a cabin altitude warning. We complied with the emergency checklist while obtaining a descent clearance from ATC. We found both of the pack switches in the OFF position. After turning on the pack switches; the aircraft began pressurizing normally and the flight continued to destination. Neither I; nor the First Officer recalled turning the pack switches off; it would be unusual for any crew member to touch those switches; and they were obviously on when I had landed the leg before because I had brought the same aircraft in. I did have a different First Officer for that flight. Because it was not a new aircraft for me; I did not 'Originate' the aircraft where I would have checked the pack switch position. It is possible that the previous First Officer accidentally turned off the pack switches instead of the bleed switches on the previous parking flow; or that somehow the switches were accidentally turned off by either of us in the course of attempting to complete our flows. It is a poor design feature of the Q400 that there is no cockpit annunciation of the pressurization air flow being turned off. Also; it would be helpful if the after start flow had the crew check that the pack switches are on; along with the bleed switches.
Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.