Narrative:

Event flight was operating on an IFR flight from bos to bhb. Approximately 30 NM southwest of rkd, ZBW cleared us to descend 'at pilot's discretion' from our cruise altitude of 15000 ft MSL to 11000 ft MSL. First officer, acting as PF, initiated the descent upon clearance receipt. Overhead rkd, I advised first officer that I was off communication #1 to call company operations on communication #2. At the time we were descending through approximately 12000 ft MSL. While talking to company operations I observed first officer select bgr approach frequency to communication #1, indicating a handoff from ZBW. When I returned to communication #1, I observed first officer descending through 10500 ft MSL. The altitude alerter had not been reset to a lower altitude than the original 11000 ft we were cleared to descend to, but since I had not been monitoring communication #1, I thought we may have been cleared to a lower altitude upon the handoff to bgr approach and that the first officer had simply forgotten to reset the alerter. At approximately 10300 ft MSL I discovered I was in error when bgr approach called us and asked to verify 'level at 11000 ft.' we quickly initiated a climb back to our assigned altitude and apologized to bgr approach for the error. Factors contributing to this incident were my inattn to the first officer's actions, and my being 'out of the communications loop' while I was off communication #1. In the future, I will take more care to make the standard altitude callouts, even while off the primary radio frequency. Also, I will avoid making calls to company operations while approaching an assigned altitude.

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Original NASA ASRS Text

Title: PNF DISTR BY COMPANY RADIO. ALT ALERTER NOT SET. ACFT DSCNT BELOW ASSIGNED ALT UNTIL CTLR QUESTIONED ALT. RETURNED TO ASSIGNED ALT.

Narrative: EVENT FLT WAS OPERATING ON AN IFR FLT FROM BOS TO BHB. APPROX 30 NM SW OF RKD, ZBW CLRED US TO DSND 'AT PLT'S DISCRETION' FROM OUR CRUISE ALT OF 15000 FT MSL TO 11000 FT MSL. FO, ACTING AS PF, INITIATED THE DSCNT UPON CLRNC RECEIPT. OVERHEAD RKD, I ADVISED FO THAT I WAS OFF COM #1 TO CALL COMPANY OPS ON COM #2. AT THE TIME WE WERE DSNDING THROUGH APPROX 12000 FT MSL. WHILE TALKING TO COMPANY OPS I OBSERVED FO SELECT BGR APCH FREQ TO COM #1, INDICATING A HDOF FROM ZBW. WHEN I RETURNED TO COM #1, I OBSERVED FO DSNDING THROUGH 10500 FT MSL. THE ALT ALERTER HAD NOT BEEN RESET TO A LOWER ALT THAN THE ORIGINAL 11000 FT WE WERE CLRED TO DSND TO, BUT SINCE I HAD NOT BEEN MONITORING COM #1, I THOUGHT WE MAY HAVE BEEN CLRED TO A LOWER ALT UPON THE HDOF TO BGR APCH AND THAT THE FO HAD SIMPLY FORGOTTEN TO RESET THE ALERTER. AT APPROX 10300 FT MSL I DISCOVERED I WAS IN ERROR WHEN BGR APCH CALLED US AND ASKED TO VERIFY 'LEVEL AT 11000 FT.' WE QUICKLY INITIATED A CLB BACK TO OUR ASSIGNED ALT AND APOLOGIZED TO BGR APCH FOR THE ERROR. FACTORS CONTRIBUTING TO THIS INCIDENT WERE MY INATTN TO THE FO'S ACTIONS, AND MY BEING 'OUT OF THE COMS LOOP' WHILE I WAS OFF COM #1. IN THE FUTURE, I WILL TAKE MORE CARE TO MAKE THE STANDARD ALT CALLOUTS, EVEN WHILE OFF THE PRIMARY RADIO FREQ. ALSO, I WILL AVOID MAKING CALLS TO COMPANY OPS WHILE APCHING AN ASSIGNED ALT.

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.