Narrative:

Altitude deviation. Just departing austin, we were at about FL205 climbing to FL210 when I received an RA which I followed, and at about the same time I disconnected the autoplt and autothrottles to manually fly the aircraft. We were entering a little area of rain showers which I also was deviating. Evidently at this same time, while I was doing all this, we received a clearance to cross hirst intersection at 11000 ft. When the aircraft was now at FL210 and stabilized from the RA, I was told from first officer our clearance was to cross hirst at 10000 ft. I did so and was level at hirst at 10000 ft when we were now talking to dfw approach, who told us to climb and maintain 11000 ft and that that should have been our altitude. We climbed to 11000 ft and asked him if there was a conflict. He said no. My copilot is sure he heard the restr as 10000 ft. I should have heard the clearance myself but I did not. I was quite busy flying the aircraft at the time. Supplemental information from acn 418569: we were at FL210. ZHU gave us a crossing restr to descend and cross hirst intersection at what I understood to be 10000 ft. I dialed in 10000 ft on the altitude selector. I thought I read back 10000 ft. After a few mins we began our descent to meet the crossing restr and I reported out of FL210 for 10000 ft. ZHU then switched us over to dfw approach as we were leveling off. When I checked in with dfw approach I reported out of 11300 ft for 10000 ft with the ATIS. After leveling at 10000 ft, approach said to maintain 11000 ft. We climbed back to 11000 ft.

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Original NASA ASRS Text

Title: MD80 CREW DSNDED BELOW THEIR CLRED ALT.

Narrative: ALTDEV. JUST DEPARTING AUSTIN, WE WERE AT ABOUT FL205 CLBING TO FL210 WHEN I RECEIVED AN RA WHICH I FOLLOWED, AND AT ABOUT THE SAME TIME I DISCONNECTED THE AUTOPLT AND AUTOTHROTTLES TO MANUALLY FLY THE ACFT. WE WERE ENTERING A LITTLE AREA OF RAIN SHOWERS WHICH I ALSO WAS DEVIATING. EVIDENTLY AT THIS SAME TIME, WHILE I WAS DOING ALL THIS, WE RECEIVED A CLRNC TO CROSS HIRST INTXN AT 11000 FT. WHEN THE ACFT WAS NOW AT FL210 AND STABILIZED FROM THE RA, I WAS TOLD FROM FO OUR CLRNC WAS TO CROSS HIRST AT 10000 FT. I DID SO AND WAS LEVEL AT HIRST AT 10000 FT WHEN WE WERE NOW TALKING TO DFW APCH, WHO TOLD US TO CLB AND MAINTAIN 11000 FT AND THAT THAT SHOULD HAVE BEEN OUR ALT. WE CLBED TO 11000 FT AND ASKED HIM IF THERE WAS A CONFLICT. HE SAID NO. MY COPLT IS SURE HE HEARD THE RESTR AS 10000 FT. I SHOULD HAVE HEARD THE CLRNC MYSELF BUT I DID NOT. I WAS QUITE BUSY FLYING THE ACFT AT THE TIME. SUPPLEMENTAL INFO FROM ACN 418569: WE WERE AT FL210. ZHU GAVE US A XING RESTR TO DSND AND CROSS HIRST INTXN AT WHAT I UNDERSTOOD TO BE 10000 FT. I DIALED IN 10000 FT ON THE ALT SELECTOR. I THOUGHT I READ BACK 10000 FT. AFTER A FEW MINS WE BEGAN OUR DSCNT TO MEET THE XING RESTR AND I RPTED OUT OF FL210 FOR 10000 FT. ZHU THEN SWITCHED US OVER TO DFW APCH AS WE WERE LEVELING OFF. WHEN I CHKED IN WITH DFW APCH I RPTED OUT OF 11300 FT FOR 10000 FT WITH THE ATIS. AFTER LEVELING AT 10000 FT, APCH SAID TO MAINTAIN 11000 FT. WE CLBED BACK TO 11000 FT.

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.