GA LTT LOW SPD BUFFET AT FL450.

Narrative

APPROX 1:40 INTO A FLT FROM CHICAGO MIDWAY TO OXNARD; CA; AT 45000 FT; THE LTT I WAS FLYING ENCOUNTERED BUFFET AND COULD NOT HOLD ALT. LEADING TO THIS EVENT; WE HAD BLOCKED 430-450 AND HAD BEEN DRIFTING UP FOR 15-20 MINS; MAINTAINING 150-155 KTS IAS. AT 44500 CTLR ASKED IF WE COULD ACCEPT 450. THERE WAS AN ACR LGT OVERTAKING AT 430. WT WAS SHOWING JUST UNDER 14000 POUNDS; OUR MAX WT FOR 450. I TOLD THE CTLR 'YES'; AND WE WERE CLRED TO MAINTAIN 450. GOING UP THE LAST 500 FT OUR SPD DROPPED TO 140 KTS IAS. LEVEL AT 450 SPD BEGAN TO DECAY. AT APPROX 125-120 KTS IAS WE ENCOUNTERED ONSET OF BUFFET. I TOLD THE CTLR WE HAD ENTERED BUFFET AND HAD TO COME DOWN. HE TOLD ME WE COULDN'T COME DOWN BECAUSE OF TFC AND THAT I SHOULD TURN TO THE R 60 DEGS UNTIL HE COULD CLR ME DOWN. WE WERE ENCOUNTERING DSNDING AIR. IF WE CONTINUED AHEAD I WAS SURE WE WOULD STALL OR UNPORT. TURNING WOULD TAKE MY AWAY FROM THE TFC BUT WAS NOT A SAFE MANEUVER. I TOLD THE CTLR I WAS TURNING AND COMING DOWN AND DSNDED 1000 FT TURNING 60 DEGS TO THE R. THE AIRLINER BELOW AND BEHIND RPTED HE HAD US VISUALLY AND WE WERE NO PROBLEM. SUBSEQUENTLY; ON BEING SWITCHED TO DENVER; WE LEARNED THERE WAS MOUNTAIN WAVE ACTIVITY RPTED BY AIRLINERS AT 420. CLRED TO 430 AND STABILIZED AT APPROX 170 KTS IAS; WE EXPERIENCED UP TO 15 KT SPD CHANGES ALONG WITH ALT CHANGES AS WE ENCOUNTERED AREAS OF ASCENDING AND DSNDING AIR. ASIDE FROM THE OBVIOUS (IF WE HAD KNOWN IT WAS A TRAP WE WOULD NOT HAVE ENTERED IT); I BELIEVE THE ACTION TAKEN WAS THE SAFEST. I TOLD THE CTLR WHAT I HAD TO DO. I BELIEVE HE WOULD HAVE TURNED THE LGT IMMEDIATELY IF THERE WAS THE SLIGHTEST DANGER OF A COLLISION. 2 CONSTRUCTIVE SUGGESTIONS: 1) A SEGMENT SHOULD BE ADDED TO INITIAL AND RECURRENT TRAINING COVERING HIGH ALT; THIN AIR FLYING. THIS IS AT THE EDGE OF THE ENVELOPE AND THERE IS NOTHING IN THE TRAINING SYLLABUS COVERING IT. 2) IF THERE IS NOT; THERE SHOULD BE TRAINING FOR THE CTLRS IN ACFT PROBLEMS AT HIGH ALT FLT; I.E.; A BUFFET IS ON THE WAY TO A STALL OR FLAME-OUT AND ANY TURNS SHOULD BE GIVEN TO THE ACFT WHICH CAN SAFELY MAKE THE TURN; NOT THE ONE IN TROUBLE.