MLG FLT HAD ALTDEV.

Narrative

CLRED BY ZNY TO CROSS FIX W OF ALLENTOWN AT 13000. ALTIMETER WAS 29.05 (LOW) CAPT (FLYING) ATTEMPTED TO PUT XING RESTRICTION IN FMC AFTER SETTING ALT IN MCP. COMPUTER WOULD NOT ACCEPT XING RESTRICTION AND WE WERE COMING UP ON FIX SO I PRESSED LEVEL CHANGE AND CONTINUED TO ATTEMPT TO PROGRAM THE COMPUTER. COPLT ASKED 'HAVE YOU BEEN CLRED LOWER; AND I LOOKED UP AND SAW US DSNDING THROUGH 13000 ON HIS ALTIMETER. DISCONNECTED AUTOPLT AND LEVELED AT 12500 AND RETURNED TO 13000. I HAD NOT CALLED FOR THE IN-RANGE CHK AND COPLT HAD NOT INITIATED IT BUT HAD RESET HIS ALTIMETER WITHOUT CALLING FOR OR CHKING MINE. I FEEL 2 FACTORS CONTRIBUTED TO THIS INCIDENT: 1) COPLT WAS FROM ANOTHER AIRLINE IN A MERGER AND FELT HE HAD BEEN 'SCREWED' IN THE SENIORITY INTEGRATION. HIS ATTITUDE WAS BAD AND HE IS RESENTFUL IN HAVING TO FLY WITH YOUNGER CAPTS. HE DOES HIS JOB IN AN EXTREMELY PASSIVE MANNER AND IS QUITE CAPABLE OF QUIETLY WATCHING SOMEONE BUST AN ALT; IN FACT; DESCRIBED DOING SO IN THE PAST. (THIS IN NO WAY DIMINISHES MY RESPONSIBILITY FOR WHAT HAPPENED.) 2) OUR AIRLINE HAS RECENTLY TERMINATED CREW MEALS AS A COST SAVINGS MEASURE; AND NEITHER OF US HAD EATEN IN SEVERAL HRS.