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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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PIC of a chartered medical flight temporarily loses control of his aircraft during descent when encountering clear air turbulence. Aircraft goes below assigned altitude. Controller notes this and reminds flight crew.
| Attributes | |
| ACN | 384270 |
| Time | |
| Date | 199710 |
| Day | Thu |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : czvr |
| State Reference | BC |
| Altitude | msl bound lower : 25700 msl bound upper : 26000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : czvr |
| Operator | other |
| Make Model Name | Any Unknown or Unlisted Aircraft Manufacturer |
| Operating Under FAR Part | Part 135 |
| Flight Phase | descent other |
| Route In Use | enroute : direct enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | Other |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| ASRS Report | 384270 |
| Person 2 | |
| Affiliation | Other |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : overshoot inflight encounter other non adherence : clearance other anomaly |
| Independent Detector | other controllera other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course flight crew : regained aircraft control other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Weather |
| Air Traffic Incident | Pilot Deviation other |
Narrative:
We were given a clearance to descend out of 39000 ft to maintain 26000 ft. Moderate turbulence had been reported for our descent. As we began our descent the turbulence increased in intensity. As we were nearing 26000 ft we got a large drop in altitude, I suspect as a result of mountain wave activity. We were correcting immediately but due to the consistent moderate turbulence we descended below our assigned altitude momentarily. Center called on the radio and said FL260 and I responded appropriately.
Original NASA ASRS Text
Title: PIC OF A CHARTERED MEDICAL FLT TEMPORARILY LOSES CTL OF HIS ACFT DURING DSCNT WHEN ENCOUNTERING CLR AIR TURB. ACFT GOES BELOW ASSIGNED ALT. CTLR NOTES THIS AND REMINDS FLC.
Narrative: WE WERE GIVEN A CLRNC TO DSND OUT OF 39000 FT TO MAINTAIN 26000 FT. MODERATE TURB HAD BEEN RPTED FOR OUR DSCNT. AS WE BEGAN OUR DSCNT THE TURB INCREASED IN INTENSITY. AS WE WERE NEARING 26000 FT WE GOT A LARGE DROP IN ALT, I SUSPECT AS A RESULT OF MOUNTAIN WAVE ACTIVITY. WE WERE CORRECTING IMMEDIATELY BUT DUE TO THE CONSISTENT MODERATE TURB WE DSNDED BELOW OUR ASSIGNED ALT MOMENTARILY. CTR CALLED ON THE RADIO AND SAID FL260 AND I RESPONDED APPROPRIATELY.
Data retrieved from NASA's ASRS site as of July 2007 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.