Light Transport; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Flight Crew Last 90 Days 60; Flight Crew Total 3000; Flight Crew Type 500
Deviation - Altitude Excursion From Assigned Altitude; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Took Evasive Action
Weather
We encountered clear air turbulence at FL320. Turbulence at the time was moderate. We encountered a 1;000 feet climb followed by a rapid downward descent of 4;000 feet plus. I disengaged the autopilot and tried to regain control. By the time we were level; we were at FL230. In the descent we did advise ATC that we were unable to maintain altitude and had experienced severe turbulence. We did not declare any emergency and there were no injuries on board or damage to aircraft. ATC did advise us that there could be a light mountain wave and turbulence before this occurred. The turbulence was not too bad up until that point. I have never encountered that in my life. The best way I can describe it was a rogue wave of air and we hit it just right. The weather was clearing up to almost clear skies when this occurred. Lesson learned is don't judge a book by its cover.
Captain reported encountering clear air turbulence during cruise and as a result were momentarily unable to maintain altitude.