CPR LTT ACFT HAD AN ALTDEV CAUSED BY AN AUTOPLT MALFUNCTION. A WDB ACFT WAS NEARBY CAUSING LTSS. LTT PLTS TURNED OFF THE AUTOPLT TO CORRECT THE SEPARATION PROBLEM.

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AT FL330 APPROX 25 MI E OF ST JOHNS VOR; WE HAD LEVELED OFF AT THE CTR ASSIGNED ALT. THE AUTOPLT WAS ENGAGED. THE CAPT AND MYSELF NOTED A 150 FT VARIATION IN ALT; WHICH IS CHARACTERISTIC OF THIS MAKE OF AUTOPLT. APPROX 2 SECONDS AFTER THE ALT VARIATION; WE HEARD THE AUDIBLE TRIM þCLICKER;þ SIGNIFYING THAT THE INTERNAL PITCH TRIM WAS IN TRANSIT. APPROX 1 1/2 SECONDS AFTER THE CLICKER BEGAN; THE ALT HOLD DISENGAGED ITSELF. THE ACFT THEN BEGAN AN IMMEDIATE; ABRUPT CLB. THE CAPT IMMEDIATELY; AND AGGRESSIVELY; BEGAN A PUSHOVER; USING THE AUTOPLT PITCH TRIM WHEEL. REALIZING THAT THE MACH.82 SPD LIMITATION WOULD BE EXCEEDED; HE MOVED HIS R HAND FROM THE PITCH TRIM WHEEL TO THE PWR LEVERS IN ORDER TO REDUCE THRUST; AND USED HIS L HAND WHILE ADJUSTING PWR WITH THE R. THE ALT ALERT WAS NOT HEARD BY EITHER CREW MEMBER. ZAB ASKED US TO VERIFY OUR ALT AS FL330. I RESPONDED THAT WE WERE LEVEL AT FL330; WHICH WAS THE INDICATED ALT AT THE TIME OF THE REPLY. THERE WAS A WDB AT OUR 11 OþCLOCK POS; AT APPROX 5 MI; WHICH WE HAD IN VISUAL CONTACT PRIOR TO AND AFTER THE MOMENT THAT THE PITCH TRIM BEGAN IN MOTION. UPON TRANSFERRING TO THE NEXT ZAB SECTOR; THE CTLR ADVISED US TO CALL IN REF TO A þPOSSIBLE ALT DEV.þ IT SHOULD BE NOTED THAT A VERY AGGRESSIVE MANEUVER WAS INITIATED IMMEDIATELY UPON DETECTING A PROBLEM IN THE PITCH TRIM. FURTHERMORE; VISUAL CONTACT WITH THE WDB WAS NEVER LOST. NOR WAS PROX TO THE ACFT EVER IN QUESTION TO EITHER ACFTþS CREW. I FEEL THAT; GIVEN THE SITUATION; THE CREW DID EVERYTHING HUMANLY POSSIBLE TO AVOID ANY FURTHER AIRSPACE INCURSIONS; ESPECIALLY GIVEN THE EXCEPTIONAL CLB PERFORMANCE OF THE LTT.