ACR MLG ON DESCENT LEVELED OFF AT INTERMEDIATE ALT WITHOUT ADVISING ATC.

Narrative

I WAS FLYING THE ACFT. WE HAD LEVELED OFF AT OUR ASSIGNED CRS ALT OF FL330. ON OUR AIRLINE THE PF MAKES ENRTE PAX ANNOUNCEMENTS. I TOLD THE CAPT I WAS GOING OFF AS I REACHED FOR THE P/A. I MADE MY ANNOUNCEMENT AND UPON COMPLETING IT; I FAILED TO TURN THE MONITOR SWITCH FOR THE PRIMARY RADIO BACK ON. I WAS ALSO FEELING QUITE RUSHED. I COMMUTE FROM A DISTANT CITY (2 TIME ZONES FROM DOMICILE) AND I DID NOT SLEEP WELL THE PREVIOUS EVENING. ALTHOUGH IT WAS AT MY DOMICILE; IT INVOLVED JET LAG PLUS WITHDRAWAL DUE TO ANOTHER FAMILY SEP. IN ADDITION; I WAS FROM A RECENTLY ACQUIRED AIRLINE (1 YR) AND THE CAPT WAS FROM THE ACQUIRING AIRLINE. ALTHOUGH WE ALL WEAR THE SAME UNIFORM; THERE IS A SEPARATE IDENTITY AND I WAS EAGER TO MAKE A GOOD IMPRESSION ON MY FIRST LEG AT THE CTLS. FINALLY; THIS CAPT WAS VERY SHARP AND PROCEDURALLY CORRECT; THE ANTITHESIS OF THE CAPT I HAD FLOWN WITH JUST 2 DAYS BEFORE. AS A RESULT I WAS STILL ADJUSTING TO THE CHANGE FROM TAKING THE INITIATIVE TO BEING MORE PASSIVE. THE NET EFFECT WAS THAT THOSE THINGS THAT USUALLY CAME AUTOMATICALLY REQUIRED CONSCIOUS THOUGHT AND I HAD NO RHYTHM. OVER SGF I WAS AWARE THAT THE RADIO SEEMED AWFULLY QUIET. AT THAT POINT I NOTICED THE CAPT SPEAKING INTO HIS MIC AND I BECAME AWARE THAT MY RADIO MONITOR WAS OFF. THE CAPT TOLD ME TO DES TO FL290 AND I REPEATED THE CLRNC. AFTER ESTABLISHING A 1500 FPM DES I MADE A 5 MI ADJUSTMENT IN MY CALCULATED DES POINT. (THIS WAS SIGNIFICANT BECAUSE AT 1000'/2 1/2 MI RATIO; IT SHOULD HAVE BEEN A 10 MI ADJUSTMENT.) I LEVELED THE ACFT AT FL310 WHILE THE CAPT WAS ATTEMPTING TO REACH THE COMPANY TO CLARIFY THE STATUS OF THE ACFT UPON ARR. (WE WERE FLYING AN EQUIP SUBSTITUTION AND THERE WAS NO PUBLISHED DATA FOR EITHER THE COCKPIT OR CABIN CREW.) AS A RESULT OF THIS DISTR THE CAPT DID NOT NOTICE MY INCORRECT LEVEL OFF. APPROX 4 MINS LATER CENTER CALLED AND ASKED OUR ALT. I IMMEDIATELY NOTICED THE DISCREPANCY BTWN THE ALT ALERTER AND THE ALTIMETER. I REPLIED; 'DSNDING OUT OF 310 FOR 290.' THE CTLR WAS UNDERSTANDABLY UPSET AND ASKED; 'DID LEVEL OFF ON YOUR OWN? YOU'VE BEEN AT 3-1-0 FOR 50 MI?' I REPLIED; 'YES; IT WAS SORT OF A MISUNDERSTANDING.' THERE WAS NO FURTHER EXCHANGE. I AM AN AVID READER OF THE 'CALLBACK' AND THIS INCIDENT IS SO TYPICAL OF WHAT I HAVE READ IN YOUR PUBLICATION SO MANY TIMES BEFORE. THE UNCOMFORTABLE 'OUT OF SYNC' FEELING IS DEFINITELY AN INDICATOR OF TROUBLE. UNFORTUNATELY; THERE IS NO SYS OTHER THAN THE TRIED AND TRUE; IE; CHKLISTS AND ESTABLISHED PROCS; FOR RESOLVING THOSE FEELINGS IN A SAFE MANNER. IN OUR CASE; WHILE CHKLISTS AND PROCS WERE FOLLOWED METICULOUSLY; DISTRS WERE ALLOWED TO DILUTE THE CREW CONCEPT.