Narrative:

Descent into atl we had an air conditioning/pressurization 'flow' light illuminate. First officer was flying the aircraft and he was given the job of monitoring the radios. I went to the pom to review and apply any procedures. We were at 12000 ft and handed off to approach control. First officer checked in with approach control about the time I finished with the procedures. We were discussing the necessary things to include in the write-up, when we both noticed the left pack pressure was much lower than the right. Somewhere in all of this we both became aware that we were approaching atl VOR and had not been given a turn to downwind by center. At this point we tried calling center 2-3 times and then started hunting for another frequency to talk with them. Our radio was on frequency X and the approach plate lists frequency Y. We assumed the radio had inadvertently been changed. We went to frequency Y and established contact with atl as we went over top atl VOR. Landing was uneventful. I was asked to call approach on the phone. On the phone approach control explained that frequency X was a good frequency and that we had a stuck microphone which had blocked the entire frequency to all aircraft. He stated that it really caused a lot of problems and that they were about to start holding when we finally made contact. I apologized for the problem, explaining that we had not even recognized that we had a stuck microphone. As the first officer and I talked later about the problem, we were still unable to identify which microphone was stuck open or when it cleared up.

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Original NASA ASRS Text

Title: FLC OF AN MD88 FOUND APCH CTLR HAPPY TO HEAR FROM THEM AFTER CHANGING TO ANOTHER FREQ SINCE THEY HAD A STUCK MIKE, AND DID NOT KNOW IT, CAUSING THE CTLR TO BE BLOCKED IN COMMUNICATING WITH OTHER ACFT.

Narrative: DSCNT INTO ATL WE HAD AN AIR CONDITIONING/PRESSURIZATION 'FLOW' LIGHT ILLUMINATE. FO WAS FLYING THE ACFT AND HE WAS GIVEN THE JOB OF MONITORING THE RADIOS. I WENT TO THE POM TO REVIEW AND APPLY ANY PROCS. WE WERE AT 12000 FT AND HANDED OFF TO APCH CTL. FO CHKED IN WITH APCH CTL ABOUT THE TIME I FINISHED WITH THE PROCS. WE WERE DISCUSSING THE NECESSARY THINGS TO INCLUDE IN THE WRITE-UP, WHEN WE BOTH NOTICED THE L PACK PRESSURE WAS MUCH LOWER THAN THE R. SOMEWHERE IN ALL OF THIS WE BOTH BECAME AWARE THAT WE WERE APCHING ATL VOR AND HAD NOT BEEN GIVEN A TURN TO DOWNWIND BY CTR. AT THIS POINT WE TRIED CALLING CTR 2-3 TIMES AND THEN STARTED HUNTING FOR ANOTHER FREQ TO TALK WITH THEM. OUR RADIO WAS ON FREQ X AND THE APCH PLATE LISTS FREQ Y. WE ASSUMED THE RADIO HAD INADVERTENTLY BEEN CHANGED. WE WENT TO FREQ Y AND ESTABLISHED CONTACT WITH ATL AS WE WENT OVER TOP ATL VOR. LNDG WAS UNEVENTFUL. I WAS ASKED TO CALL APCH ON THE PHONE. ON THE PHONE APCH CTL EXPLAINED THAT FREQ X WAS A GOOD FREQ AND THAT WE HAD A STUCK MIKE WHICH HAD BLOCKED THE ENTIRE FREQ TO ALL ACFT. HE STATED THAT IT REALLY CAUSED A LOT OF PROBS AND THAT THEY WERE ABOUT TO START HOLDING WHEN WE FINALLY MADE CONTACT. I APOLOGIZED FOR THE PROB, EXPLAINING THAT WE HAD NOT EVEN RECOGNIZED THAT WE HAD A STUCK MIKE. AS THE FO AND I TALKED LATER ABOUT THE PROB, WE WERE STILL UNABLE TO IDENT WHICH MIKE WAS STUCK OPEN OR WHEN IT CLRED UP.

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.