 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
A B737-700 pressurization warning alerted at the same time the autopilot disconnected while descending through FL345 to FL340. The cabin altitude warning horn confused the crew who thought for a while it was the autopilot disconnect warning. Once the pressurization anomaly was detected the descent continued to 16;000 feet and the QRH completed.
| Attributes | |
| ACN | 1278146 |
| Time | |
| Date | 201507 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Pressurization System |
| Person 1 | |
| Function | Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 176 Flight Crew Type 10800 |
| Person 2 | |
| Function | First Officer |
| Experience | Flight Crew Last 90 Days 154 Flight Crew Type 6600 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Altitude Overshoot Deviation - Procedural Clearance |
Narrative:
Descending to and leveling at FL340; the cabin altitude warning horn sounded. After a few seconds of identifying the nature of the horn; we donned the oxygen masks and established communication with each other. We discovered the cabin altitude had reached 10;000. In the confusion of the emergency; the aircraft had descended through the altitude FL340. Recognizing that we had in fact a cabin altitude warning quickly; such as a warning light that is not installed on this aircraft. We could have assessed the situation in a calm; coordinated manner. Until you experience a true pressurization emergency; it is hard to describe the confusion associated with something so simple. When you do the cabin altitude warning brief at the beginning of the day; really think about the sound and what that means you are going to do. Try donning your mask someday with the headsets and glasses and 'establish communication.' it is more distracting than you think when you are just briefing it. Because of this event; the lack of a cabin altitude warning light in some aircraft seems to be an oversight on safety. When you get a horn or any warning for that matter; there needs to be a visual cue associated. I strongly advise the installation of the light on all aircraft.
Original NASA ASRS Text
Title: A B737-700 pressurization warning alerted at the same time the autopilot disconnected while descending through FL345 to FL340. The Cabin Altitude Warning horn confused the crew who thought for a while it was the autopilot disconnect warning. Once the pressurization anomaly was detected the descent continued to 16;000 feet and the QRH completed.
Narrative: Descending to and leveling at FL340; the Cabin Altitude Warning horn sounded. After a few seconds of identifying the nature of the horn; we donned the oxygen masks and established communication with each other. We discovered the cabin altitude had reached 10;000. In the confusion of the emergency; the aircraft had descended through the altitude FL340. Recognizing that we had in fact a cabin altitude warning quickly; such as a warning light that is not installed on this aircraft. We could have assessed the situation in a calm; coordinated manner. Until you experience a true pressurization emergency; it is hard to describe the confusion associated with something so simple. When you do the cabin altitude warning brief at the beginning of the day; really think about the sound and what that means you are going to do. Try donning your mask someday with the headsets and glasses and 'establish communication.' It is more distracting than you think when you are just briefing it. Because of this event; the lack of a Cabin Altitude Warning light in some aircraft seems to be an oversight on safety. When you get a horn or any warning for that matter; there needs to be a visual cue associated. I strongly advise the installation of the light on all aircraft.
Data retrieved from NASA's ASRS site 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.