A320 FLC ENCOUNTERS MOUNTAIN WAVE ACTIVITY. ACFT HAS OVERSPD AND ALT EXCURSION.

Narrative

DURING CRUISE; ENTERED MOUNTAIN WAVE AND WIND CHANGE WITH LIGHT TURB. SPD INCREASED FROM 260 KIAS/MACH .84 TO 275 KIAS/MACH .84 IN 2 SECONDS. REMAINED IN OVERSPD RANGE FOR 4 SECONDS. WHEN AIRSPD INCREASE DETECTED APCHING RED ARC; SELECTED MACH .76. AIRSPD CONTINUED TO INCREASE ACCOMPANIED BY ALT INCREASE FROM UPDRAFT. RECEIVED MASTER WARNING FOR OVERSPD FOLLOWED BY ALT ALERT AS ACFT CONTINUED TO CLB. SEAT BELT SIGN WAS TURNED ON. FMA READ MACH/ALT CRUISE/NAV. HOWEVER; WE DID NOT DETECT THAT THE AUTOPLT WAS DISENGAGED. AFTER AIRSPD DECREASED AND DSCNT CORRECTION NOT BEING MADE; PULLED FOR OP DEC. WHEN STILL NOT CORRECTING; PUSHED AUTOPLT DISCONNECT BUTTON AND REALIZED; AT THAT TIME; THAT THE AUTOPLT WAS NOT ENGAGED. A CORRECTION WAS HAND FLOWN WITHOUT INCIDENT AND RPTED TO ATC. I NOW REMEMBER THAT THE AUTOPLT DISENGAGED AT MACH .83 AND A PITCH UP WAS INITIATED; UNTIL I REDUCED BELOW MACH .83. RESULTED IN SIGNIFICANT CLB RATE SUSTAINED BY 1-G WHICH WAS COMMANDED USING NEUTRAL STICK. LONG STABILITY WAS NOT SACRIFICED WITH AIRSPD DECREASE. THE AUTOPLT DISENGAGEMENT WAS MASKED BY MASTER WARNING FOR OVERSPD AND ALT ALERT. THE AUTOPLT DISENGAGE ECAM WAS PRESENT BUT UNNOTICED BY SELF OR FO AS ALL EYES WERE ELSEWHERE. THE SIT RESULTED IN A TOTAL ALT INCREASE OF ALMOST 1000 FT. THERE WAS NO WARNING OF MOUNTAIN WAVE OR WIND CHANGE BUT SOME OF THE ALT INCREASE WOULD HAVE BEEN CTLED WITH SOONER AWARENESS OF AUTOPLT DISENGAGEMENT. AWARENESS OF THIS POSSIBLE SCENARIO AND DISCUSSION WITH OTHER A-320 PLTS MAY AID OTHERS IN MAKING A QUICKER RESPONSE. A DIFFERENT AURAL WARNING; AS WITH ALL OTHER ACFT I'VE FLOWN; FOR OVERSPD WOULD ALSO ENHANCE DETECTION OF BOTH WARNINGS.