B737-700
Flight Crew Air Transport Pilot (ATP)
Deviation - Speed All Types; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action
Aircraft; Weather
The location of the event was approximately 40 miles west of the TAY VORTAC at FL 410. The First Officer was flying and the Captain was monitoring. We had been cruising at FL410 for approximately 20-30 minutes in light chop and aware of isolated storms enroute. The radar was being used in both manual and auto mode to attempt to 'paint' any potential weather enroute. Our optimum altitude in the FMC was FL410 and we had just entered what appeared to be wispy high clouds. While cruising at .79 mach in light chop (in the proverbial milk carton) the airspeed began to increase notably (much like mountain wave); and it became necessary for the First Officer to manually retard the thrust levers to approximately a 'stand up' position on the quadrant. Within a few seconds the 'increase shear' quickly became a 'decreasing shear' and the (yellow) footer quickly came into view followed very rapidly by the (red hashed) stick shaker. Full thrust (to the stops) was instantly applied; despite the autothrottles trying to reduce thrust. The aircraft; though in the stick shaker was NOT stalled as no uncommanded movements of the aircraft were encountered; no altitude loss was noted and the wings were always level and responding to input. The Captain asked ATC for lower (FL390) and simultaneously pressed level change to FL390 as ATC cleared us and asked if we needed any assistance. The aircraft pitch commands did not display a descent out of FL410; hence the First Officer disengaged the autopilot and began the descent (the autothrottles) continued to resist increasing thrust by the First Officer as the aircraft continued to experience periodic stick shaker indications. The Captain disengaged the autothrottles and increased thrust. Shortly after we began our descent to FL390 the aircraft airspeed began to return towards normal. No exceedances were noted; however; to be certain; upon landing the Captain called for Maintenance to check for engine exceedance...none was discovered on the instruments or in the FMC by the Technician.
B737-700 Captain reports encountering up and downdrafts at FL410 requiring full thrust to maintain flying speed; followed by a descent to FL390.