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P46T pilot reported ATC issued a terrain warning on approach to jac when he had trouble maintaining altitude because of mountain wave.
| Attributes | |
| ACN | 1387107 |
| Time | |
| Date | 201609 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | JAC.Airport |
| State Reference | WY |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | PA-46 Malibu/Malibu Mirage/Malibu Matrix |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Descent |
| Route In Use | Direct |
| Flight Plan | IFR |
| Person 1 | |
| Function | Pilot Flying Single Pilot |
| Qualification | Flight Crew Instrument Flight Crew Private Flight Crew Multiengine |
| Experience | Flight Crew Last 90 Days 29 Flight Crew Total 1065 Flight Crew Type 156 |
| Events | |
| Anomaly | Deviation - Altitude Excursion From Assigned Altitude Inflight Event / Encounter CFTT / CFIT Inflight Event / Encounter Weather / Turbulence |
Narrative:
I was on an IFR flight plan (in VMC; below a cloud deck) assigned 13;000 feet on descent into jac. I could see mountainous terrain below me; falling away as I was approaching the valley to jackson; wy. There was continuous moderate turbulence; affecting the airplane both in pitch and in roll; due to what I suspected was a mountain wave.at one point; I realized the autopilot had disconnected and we were in a nose up attitude. I lowered the nose to regain airspeed and in the process descended a few hundred feet.ATC gave me a terrain alert and I attempted to regain my assigned altitude; but it took about a minute to fight the descending wave. By the time I was through the most turbulent section; I was able to report the airport in sight and request a visual approach.after landing; I was instructed to call salt lake center and I provided this accounting which had caused a loss of terrain separation.in hindsight; I could have reported the turbulence sooner and perhaps requested a block altitude. Or better (since I had the airport in sight) I could have requested a visual approach sooner to relieve ATC of the terrain clearance.
Original NASA ASRS Text
Title: P46T pilot reported ATC issued a terrain warning on approach to JAC when he had trouble maintaining altitude because of mountain wave.
Narrative: I was on an IFR flight plan (in VMC; below a cloud deck) assigned 13;000 feet on descent into JAC. I could see mountainous terrain below me; falling away as I was approaching the valley to Jackson; WY. There was continuous moderate turbulence; affecting the airplane both in pitch and in roll; due to what I suspected was a mountain wave.At one point; I realized the autopilot had disconnected and we were in a nose up attitude. I lowered the nose to regain airspeed and in the process descended a few hundred feet.ATC gave me a terrain alert and I attempted to regain my assigned altitude; but it took about a minute to fight the descending wave. By the time I was through the most turbulent section; I was able to report the airport in sight and request a visual approach.After landing; I was instructed to call Salt Lake Center and I provided this accounting which had caused a loss of terrain separation.In hindsight; I could have reported the turbulence sooner and perhaps requested a block altitude. Or better (since I had the airport in sight) I could have requested a visual approach sooner to relieve ATC of the terrain clearance.
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.