Narrative:

We were on vectors with approach control when we were cleared to a lower altitude. I was the PF. Both of us heard a new altitude of 2500 ft MSL. We both pointed to the new altitude I set (2500 ft) and my first officer read back the clearance to 2500 ft. At the time we were about 6000 ft. During my approach briefing, I talked about the towers on top of a ridge south of the airport up to 2049 ft MSL. We soon broke out of the clouds and leveled off at 2500 ft MSL in VFR conditions. I mentioned that 2500 ft seemed low with the towers nearby. I looked at the approach chart and saw that the procedure turn altitude was 2600 ft. I then assumed that we were at a minimum vectoring altitude. We were at 2500 ft for about 1 min when bhm approach told us we were supposed to be at 3500 ft. He gave us a new heading further away from the towers and a new altitude of 3000 ft. He apologized for missing our readback of 2500 ft and we continued on for our landing. I am certain we heard a clearance to 2500 ft. However, I can't imagine the controller ever clears anyone to that altitude so close to the towers. We may have heard the wrong altitude and the controller did hear the wrong readback. It just never registered with us or the controller. We followed all company procedures in the cockpits, but that wasn't enough. We as pilots and controllers both need to listen to each other more closely. Another possible factor: approach control was at the same time trying to communicate with an open cockpit airplane whose radio calls were extremely long and distracting to anyone on our frequency.

Related reports:

Google
 

Original NASA ASRS Text

Title: AN MD88 FLT CREW THOUGHT THEY RECEIVED DSCNT TO 2500 FT AND READ IT BACK. BHM APCH CTLR NOTIFIED THE FLT CREW THAT THEY WERE SUPPOSED TO BE AT 3500 FT.

Narrative: WE WERE ON VECTORS WITH APCH CTL WHEN WE WERE CLRED TO A LOWER ALT. I WAS THE PF. BOTH OF US HEARD A NEW ALT OF 2500 FT MSL. WE BOTH POINTED TO THE NEW ALT I SET (2500 FT) AND MY FO READ BACK THE CLRNC TO 2500 FT. AT THE TIME WE WERE ABOUT 6000 FT. DURING MY APCH BRIEFING, I TALKED ABOUT THE TWRS ON TOP OF A RIDGE S OF THE ARPT UP TO 2049 FT MSL. WE SOON BROKE OUT OF THE CLOUDS AND LEVELED OFF AT 2500 FT MSL IN VFR CONDITIONS. I MENTIONED THAT 2500 FT SEEMED LOW WITH THE TWRS NEARBY. I LOOKED AT THE APCH CHART AND SAW THAT THE PROC TURN ALT WAS 2600 FT. I THEN ASSUMED THAT WE WERE AT A MINIMUM VECTORING ALT. WE WERE AT 2500 FT FOR ABOUT 1 MIN WHEN BHM APCH TOLD US WE WERE SUPPOSED TO BE AT 3500 FT. HE GAVE US A NEW HDG FURTHER AWAY FROM THE TWRS AND A NEW ALT OF 3000 FT. HE APOLOGIZED FOR MISSING OUR READBACK OF 2500 FT AND WE CONTINUED ON FOR OUR LNDG. I AM CERTAIN WE HEARD A CLRNC TO 2500 FT. HOWEVER, I CAN'T IMAGINE THE CTLR EVER CLRS ANYONE TO THAT ALT SO CLOSE TO THE TWRS. WE MAY HAVE HEARD THE WRONG ALT AND THE CTLR DID HEAR THE WRONG READBACK. IT JUST NEVER REGISTERED WITH US OR THE CTLR. WE FOLLOWED ALL COMPANY PROCS IN THE COCKPITS, BUT THAT WASN'T ENOUGH. WE AS PLTS AND CTLRS BOTH NEED TO LISTEN TO EACH OTHER MORE CLOSELY. ANOTHER POSSIBLE FACTOR: APCH CTL WAS AT THE SAME TIME TRYING TO COMMUNICATE WITH AN OPEN COCKPIT AIRPLANE WHOSE RADIO CALLS WERE EXTREMELY LONG AND DISTRACTING TO ANYONE ON OUR FREQ.

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.