Narrative:

Cruising at FL330, autoplt and autothrottles disengaged seemingly concurrent with master caution yaw damper off and mach trim inoperative lights. Flew aircraft in to atl with only slightly degraded control due to yaw damper inoperative. Occasionally, during speed and trim changes, we could feel the tail yaw. We notified the flight attendants of condition and they reported a slight feeling of abnormal aircraft movement and no unusual noises. The captain and I could not locate any suitable abnormal procedures to match aircraft condition. After it was imminent that we were going to get vectors and prominent speed changes, the captain declared an emergency and we landed without incident. After landing, while waiting for traffic, we noticed the C17 dfg system 'a' circuit breaker was popped.

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Original NASA ASRS Text

Title: AN MD80 IN CRUISE AT FL330 DECLARED AN EMER DUE TO AUTOPLT AND AUTOTHROTTLES DISENGAGED WITH MASTER CAUTION YAW DAMPER AND MACH TRIM INOP LIGHTS. AFTER LNDG FOUND DFG 'A' CIRCUIT BREAKER TRIPPED.

Narrative: CRUISING AT FL330, AUTOPLT AND AUTOTHROTTLES DISENGAGED SEEMINGLY CONCURRENT WITH MASTER CAUTION YAW DAMPER OFF AND MACH TRIM INOP LIGHTS. FLEW ACFT IN TO ATL WITH ONLY SLIGHTLY DEGRADED CTL DUE TO YAW DAMPER INOP. OCCASIONALLY, DURING SPD AND TRIM CHANGES, WE COULD FEEL THE TAIL YAW. WE NOTIFIED THE FLT ATTENDANTS OF CONDITION AND THEY RPTED A SLIGHT FEELING OF ABNORMAL ACFT MOVEMENT AND NO UNUSUAL NOISES. THE CAPT AND I COULD NOT LOCATE ANY SUITABLE ABNORMAL PROCS TO MATCH ACFT CONDITION. AFTER IT WAS IMMINENT THAT WE WERE GOING TO GET VECTORS AND PROMINENT SPD CHANGES, THE CAPT DECLARED AN EMER AND WE LANDED WITHOUT INCIDENT. AFTER LNDG, WHILE WAITING FOR TFC, WE NOTICED THE C17 DFG SYS 'A' CIRCUIT BREAKER WAS POPPED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.