Narrative:

On descent to mobile was inbound from the east. Another aircraft was heading northwest from southeast overflying mobile. We thought we were cleared to 6000 and began descent from 11000. The controller called traffic 10-11 O'clock, 6 mi at 6000. I replied we were also cleared to 6000 and the controller stated we were cleared to 7000 to climb to 7000. I climbed to 7000 immediately and asked the first officer if he remembered hearing 7000. He stated he really couldn't remember. I very definitely remembered reading back 'descending to 6000.' just prior to descending, we were advised the WX at mobile was obscured by fog, visibility 3 mi, runway 14 RVR 800-1000. We cannot initiate an approach to a runway with that RVR and asked for runway 32 visibility. The controller stated runway 32 visibility 3 mi and asked if we wanted 32 and we said yes and began setting up for 32. After we experienced the communication breakdown involving the altitude confusion, we were vectored for ILS 32, we were not receiving the identify and advised the controller who gave us another vector and basically stated they had forgotten to switch the approach from 14 to 32. We then intercepted the ILS and landed without incident. I called approach control from my hotel and they advised that there had never been a lack of separation standards and they missed my readback to 6000, and saw no need to peruse the matter further, we exchanged goodnight's and hung up. From my point of view, the greatest contributor to this occurrence was fatigue caused by lack of sleep due to a schedule continuous duty overnight the night before this scheduled continuous duty overnight, and the inability to force sleep during daylight hours with no conditioning of the body and mind with a regular schedule. Airline's scheduling policies are unsafe in this respect and abuse every intent of scheduling regulations.

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Original NASA ASRS Text

Title: ALTDEV. CLRED 7000 FLT WAS DSNDING TO 6000 WHEN CORRECTED BY CTLR ACCOUNT TFC AT 6000.

Narrative: ON DSCNT TO MOBILE WAS INBOUND FROM THE E. ANOTHER ACFT WAS HDG NW FROM SE OVERFLYING MOBILE. WE THOUGHT WE WERE CLRED TO 6000 AND BEGAN DSCNT FROM 11000. THE CTLR CALLED TFC 10-11 O'CLOCK, 6 MI AT 6000. I REPLIED WE WERE ALSO CLRED TO 6000 AND THE CTLR STATED WE WERE CLRED TO 7000 TO CLB TO 7000. I CLBED TO 7000 IMMEDIATELY AND ASKED THE FO IF HE REMEMBERED HEARING 7000. HE STATED HE REALLY COULDN'T REMEMBER. I VERY DEFINITELY REMEMBERED READING BACK 'DSNDING TO 6000.' JUST PRIOR TO DSNDING, WE WERE ADVISED THE WX AT MOBILE WAS OBSCURED BY FOG, VISIBILITY 3 MI, RWY 14 RVR 800-1000. WE CANNOT INITIATE AN APCH TO A RWY WITH THAT RVR AND ASKED FOR RWY 32 VISIBILITY. THE CTLR STATED RWY 32 VISIBILITY 3 MI AND ASKED IF WE WANTED 32 AND WE SAID YES AND BEGAN SETTING UP FOR 32. AFTER WE EXPERIENCED THE COM BREAKDOWN INVOLVING THE ALT CONFUSION, WE WERE VECTORED FOR ILS 32, WE WERE NOT RECEIVING THE IDENT AND ADVISED THE CTLR WHO GAVE US ANOTHER VECTOR AND BASICALLY STATED THEY HAD FORGOTTEN TO SWITCH THE APCH FROM 14 TO 32. WE THEN INTERCEPTED THE ILS AND LANDED WITHOUT INCIDENT. I CALLED APCH CTL FROM MY HOTEL AND THEY ADVISED THAT THERE HAD NEVER BEEN A LACK OF SEPARATION STANDARDS AND THEY MISSED MY READBACK TO 6000, AND SAW NO NEED TO PERUSE THE MATTER FURTHER, WE EXCHANGED GOODNIGHT'S AND HUNG UP. FROM MY POINT OF VIEW, THE GREATEST CONTRIBUTOR TO THIS OCCURRENCE WAS FATIGUE CAUSED BY LACK OF SLEEP DUE TO A SCHEDULE CONTINUOUS DUTY OVERNIGHT THE NIGHT BEFORE THIS SCHEDULED CONTINUOUS DUTY OVERNIGHT, AND THE INABILITY TO FORCE SLEEP DURING DAYLIGHT HRS WITH NO CONDITIONING OF THE BODY AND MIND WITH A REGULAR SCHEDULE. AIRLINE'S SCHEDULING POLICIES ARE UNSAFE IN THIS RESPECT AND ABUSE EVERY INTENT OF SCHEDULING REGS.

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.