Narrative:

Altitude deviation. We had been given descent clearance to cross 35 mi west of allentown at FL180. As the aircraft went into the altitude capture mode, we got a new clearance to cross 10 mi west of fjc at 13000 ft. Because the airplane was already in the altitude capture mode as captain set a lower altitude of 11000 ft to keep our descent going and to make the new restr. I just never reset the correct altitude, as I became busy with other duties. This was my fault and was brought to our attention by the controller at nyc. We immediately climbed up to 13000 ft and I do not think that there was a conflict with any other aircraft. Supplemental information from acn 428146: during descent, we were given a crossing restr of 35 mi west of allentown, maintain 18000 ft. While attempting to make that restr, we were given an additional crossing altitude of 10 mi west of allentown at 13000 ft. 11000 ft was dialed into the altitude selecting. 13000 ft was acknowledged, but due to hurriedness to get down, neither captain nor myself caught the misdialed altitude. We leveled at 11000 ft and ZNY advised that we should be at 13000 ft. We then acknowledged our mistake and expedited back to 13000 ft. No further problems for the remainder of flight.

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Original NASA ASRS Text

Title: MD80 CREW HAD ALT EXCURSION ON DSCNT.

Narrative: ALTDEV. WE HAD BEEN GIVEN DSCNT CLRNC TO CROSS 35 MI W OF ALLENTOWN AT FL180. AS THE ACFT WENT INTO THE ALT CAPTURE MODE, WE GOT A NEW CLRNC TO CROSS 10 MI W OF FJC AT 13000 FT. BECAUSE THE AIRPLANE WAS ALREADY IN THE ALT CAPTURE MODE AS CAPT SET A LOWER ALT OF 11000 FT TO KEEP OUR DSCNT GOING AND TO MAKE THE NEW RESTR. I JUST NEVER RESET THE CORRECT ALT, AS I BECAME BUSY WITH OTHER DUTIES. THIS WAS MY FAULT AND WAS BROUGHT TO OUR ATTN BY THE CTLR AT NYC. WE IMMEDIATELY CLBED UP TO 13000 FT AND I DO NOT THINK THAT THERE WAS A CONFLICT WITH ANY OTHER ACFT. SUPPLEMENTAL INFO FROM ACN 428146: DURING DSCNT, WE WERE GIVEN A XING RESTR OF 35 MI W OF ALLENTOWN, MAINTAIN 18000 FT. WHILE ATTEMPTING TO MAKE THAT RESTR, WE WERE GIVEN AN ADDITIONAL XING ALT OF 10 MI W OF ALLENTOWN AT 13000 FT. 11000 FT WAS DIALED INTO THE ALT SELECTING. 13000 FT WAS ACKNOWLEDGED, BUT DUE TO HURRIEDNESS TO GET DOWN, NEITHER CAPT NOR MYSELF CAUGHT THE MISDIALED ALT. WE LEVELED AT 11000 FT AND ZNY ADVISED THAT WE SHOULD BE AT 13000 FT. WE THEN ACKNOWLEDGED OUR MISTAKE AND EXPEDITED BACK TO 13000 FT. NO FURTHER PROBS FOR THE REMAINDER OF FLT.

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.