 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Upon encountering a severe mountain wave and associated turbulence at FL390; a B737-700 flight crew declared an emergency due to the inability to maintain their cleared altitude and struggled to maintain control until the conditions abated.
| Attributes | |
| ACN | 949987 |
| Time | |
| Date | 201105 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Environment | |
| Flight Conditions | IMC |
| Light | Dusk |
| Aircraft 1 | |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Person 1 | |
| Function | Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 203 |
| Events | |
| Anomaly | Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance Deviation - Speed All Types Inflight Event / Encounter Weather / Turbulence |
Narrative:
We were unable to maintain our cruise altitude of FL390 due to severe mountain wave and turbulence. The aircraft was going between a high speed and low speed buffet and climbed approximately 800 ft then descended 1;500 ft or so. An emergency was declared and I don't believe there was a loss of separation of traffic. We called the flight attendants to see if there were any injuries and made a PA to the passengers to update them on the situation. No injuries were sustained as everyone was seated. We landed uneventfully at our destination.
Original NASA ASRS Text
Title: Upon encountering a severe mountain wave and associated turbulence at FL390; a B737-700 flight crew declared an emergency due to the inability to maintain their cleared altitude and struggled to maintain control until the conditions abated.
Narrative: We were unable to maintain our cruise altitude of FL390 due to severe mountain wave and turbulence. The aircraft was going between a high speed and low speed buffet and climbed approximately 800 FT then descended 1;500 FT or so. An emergency was declared and I don't believe there was a loss of separation of traffic. We called the flight attendants to see if there were any injuries and made a PA to the passengers to update them on the situation. No injuries were sustained as everyone was seated. We landed uneventfully at our destination.
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.