Narrative:

I was descending originally out of 7000 ft for 5000 ft on a vector for the visual 6 at ack. The approach frequency was busy as well as our company frequency at the time which we are required to monitor. I thought what I heard was a handoff for me to call ack tower. I acknowledged 'aircraft X to nantucket, roger' and switched over to ack tower. I called them 20 northwest, inbound with ATIS out of 3700 ft for 3000 ft. They asked me if I was VFR or IFR. I stated 'I believe I was on a handoff, still on an IFR flight plan.' they said no I was not and to call cape approach again. I called back again, and cape said I was not handed off and said to me 'well, now you might as well continue to 3000 ft!' I suddenly realized I was not cleared originally below 5000 ft, but thought I had been, along with the supposed handoff to the tower. Now I was out of 3300 ft for 3000 ft. All continued fine and I was handed off to tower. Tower cleared me for landing. Upon arrival, I was instructed to call cape approach by phone. I did so, and spoke to a nice guy there who reported himself as the supervisor there (I don't recall his name). He said to me that 'even though it's not really a big deal now,' he wanted me to be aware of what I had done and that come the busy season, we all need more of a heads-up and listen more carefully. He knows I responded accidentally for another handoff to ack tower, but could not get back to me before I switched over. Also, he stated he had to vector a BE1900 to a heading of 170 degrees as a result of my descent. He was reassuring that this was not an incident to worry about and I admitted my error in thinking I was cleared for further descent and handoff to tower.

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Original NASA ASRS Text

Title: C402 CREW, IN DSCNT TO ACK, OVERSHOT THEIR ASSIGNED ALT, RESPONDING TO ANOTHER'S CLRNC.

Narrative: I WAS DSNDING ORIGINALLY OUT OF 7000 FT FOR 5000 FT ON A VECTOR FOR THE VISUAL 6 AT ACK. THE APCH FREQ WAS BUSY AS WELL AS OUR COMPANY FREQ AT THE TIME WHICH WE ARE REQUIRED TO MONITOR. I THOUGHT WHAT I HEARD WAS A HDOF FOR ME TO CALL ACK TWR. I ACKNOWLEDGED 'ACFT X TO NANTUCKET, ROGER' AND SWITCHED OVER TO ACK TWR. I CALLED THEM 20 NW, INBOUND WITH ATIS OUT OF 3700 FT FOR 3000 FT. THEY ASKED ME IF I WAS VFR OR IFR. I STATED 'I BELIEVE I WAS ON A HDOF, STILL ON AN IFR FLT PLAN.' THEY SAID NO I WAS NOT AND TO CALL CAPE APCH AGAIN. I CALLED BACK AGAIN, AND CAPE SAID I WAS NOT HANDED OFF AND SAID TO ME 'WELL, NOW YOU MIGHT AS WELL CONTINUE TO 3000 FT!' I SUDDENLY REALIZED I WAS NOT CLRED ORIGINALLY BELOW 5000 FT, BUT THOUGHT I HAD BEEN, ALONG WITH THE SUPPOSED HDOF TO THE TWR. NOW I WAS OUT OF 3300 FT FOR 3000 FT. ALL CONTINUED FINE AND I WAS HANDED OFF TO TWR. TWR CLRED ME FOR LNDG. UPON ARR, I WAS INSTRUCTED TO CALL CAPE APCH BY PHONE. I DID SO, AND SPOKE TO A NICE GUY THERE WHO RPTED HIMSELF AS THE SUPVR THERE (I DON'T RECALL HIS NAME). HE SAID TO ME THAT 'EVEN THOUGH IT'S NOT REALLY A BIG DEAL NOW,' HE WANTED ME TO BE AWARE OF WHAT I HAD DONE AND THAT COME THE BUSY SEASON, WE ALL NEED MORE OF A HEADS-UP AND LISTEN MORE CAREFULLY. HE KNOWS I RESPONDED ACCIDENTALLY FOR ANOTHER HDOF TO ACK TWR, BUT COULD NOT GET BACK TO ME BEFORE I SWITCHED OVER. ALSO, HE STATED HE HAD TO VECTOR A BE1900 TO A HDG OF 170 DEGS AS A RESULT OF MY DSCNT. HE WAS REASSURING THAT THIS WAS NOT AN INCIDENT TO WORRY ABOUT AND I ADMITTED MY ERROR IN THINKING I WAS CLRED FOR FURTHER DSCNT AND HDOF TO TWR.

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.