AN A319 LEAVES ITS ASSIGNED ALT OF FL370 WHEN IT ENCOUNTERS A MOUNTAIN WAVE WITH A SUBSEQUENT AUTOPLT DISCONNECT WHEN APCHING OPPOSITE DIRECTION TFC; A B747 AT FL390 OVER ALS; CO.

Narrative

DURING CRUISE WE ENCOUNTERED MOUNTAIN WAVE JUST AS AN AIRLINE B747 PASSED OVER US AT FL390. DUE TO MOUNTAIN WAVE ACTION WE HAD AN OVERSPD AND THE AUTOPLT DISCONNECTED AND THE ACFT LEFT OUR ASSIGNED ALT IN A CLB. WE GAINED 400 FT BEFORE WE WERE ABLE TO ARREST THE CLB MANUALLY AND AS A RESULT CAUSED AN ALERT ON ZDV'S COMPUTER. A CONTRIBUTING FACTOR WAS THAT WE GOT NO AURAL OR VISUAL WARNING THAT THE AUTOPLT DISCONNECTED. OUR ACFT WAS EXTREMELY LIGHT DUE TO MAINT FERRY FLT -- APPROX 107000 LBS. THERE WAS A DELAYED RESPONSE BY AUTOTHRUST TO OVERSPD CONDITION CAUSED BY MOUNTAIN WAVE. FACTORS AFFECTING QUALITY OF HUMAN PERFORMANCE: A319 AUTOMATION IN NORMAL LAW PREVENTED US FROM BEING ABLE TO PITCH THE NOSE OVER TO RETURN TO FL370 DURING OVERSPD CONDITION. SUPPLEMENTAL INFO FROM ACN 469827: ACFT WAS ON AUTOPLT WITH MANAGED SPD (AUTOTHROTTLE). AIRSPD INCREASED BEYOND BARBER POLE. AUTOPLT KICKED OFF AND ACFT STARTED SMALL CLB TO RETARD AIRSPD. AFTER CLB OF 300-400 FT; I PUSHED OVER NOSE TO DSND BACK TO FL370. AS THIS WAS TAKING PLACE; A B747 WAS PASSING OVERHEAD AT FL390. NO TCASII ADVISORY TOOK PLACE.