Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 25; Flight Crew Total 7600; Flight Crew Type 500
Workload; Situational Awareness; Distraction; Training / Qualification
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Weather / Turbulence
Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification
Aircraft; Procedure; Weather
In level flight at FL410 after being in cruise at altitude for approximately 1/2 hour; we experienced some moderate turbulence. Then we felt a buffet and the airspeed started decreasing. The autopilot started pitching the aircraft nose high to maintain altitude. I increased to max take-off power and disconnected the autopilot. We could not maintain altitude and the airspeed was decreasing so we requested descent to FL390. Upon reaching FL390 we continued to feel buffet and requested FL370. We continued the descent to FL370 and the turbulence cleared up. We continued the flight at FL370 for approximately 30 minutes in light turbulence. We requested FL390 for the rest of the flight and did not have any turbulence at FL390.
A G200 experienced an altitude loss in moderate turbulence at FL410 so after the autopilot pitched up and aircraft speed decreased to maintain FL410; the crew descended to FL370 to maintain stable flight.