Narrative:

While in cruise and prior to descent from FL410, chief purser asked so to check on close connections for passenger upon our arrival. So began using ACARS radio to do so. A short time later, still in cruise, the first officer asked to be excused for 'physiological reasons.' shortly after that ATC cleared us to cross 85 mi south of fak VOR at FL230. I read it back, put it in the cleared altitude window (23000 ft) and began descent to comply with issued clearance. During descent first officer returned to cockpit and I advised him of the clearance. He then began flying again and descended to FL230. Shortly after level off at FL230 the ATC controller requested our altitude. I responded 'level at FL230.' he came back with a climb clearance to FL240, which we did. He said he had cleared us to FL270!? I thought I heard FL230, and due to minor distrs (i.e., so on company radio) and physiological need (of first officer to the lavatory) I was the only one who heard the clearance! Supplemental information from acn 244957: it was a easy and honest mistake, but we are still unsure of who was at fault -- ATC or captain, who didn't hear proper readback. In future I believe a minimum of 2 crew members should hear and confirm all ATC instructions. If a 2-MAN crew, maybe instructions should be confirmed with ATC upon return of missing crew member.

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Original NASA ASRS Text

Title: ALTDEV ALT OVERSHOT AND ALT XING RESTRICTION NOT MET.

Narrative: WHILE IN CRUISE AND PRIOR TO DSCNT FROM FL410, CHIEF PURSER ASKED SO TO CHK ON CLOSE CONNECTIONS FOR PAX UPON OUR ARR. SO BEGAN USING ACARS RADIO TO DO SO. A SHORT TIME LATER, STILL IN CRUISE, THE FO ASKED TO BE EXCUSED FOR 'PHYSIOLOGICAL REASONS.' SHORTLY AFTER THAT ATC CLRED US TO CROSS 85 MI S OF FAK VOR AT FL230. I READ IT BACK, PUT IT IN THE CLRED ALT WINDOW (23000 FT) AND BEGAN DSCNT TO COMPLY WITH ISSUED CLRNC. DURING DSCNT FO RETURNED TO COCKPIT AND I ADVISED HIM OF THE CLRNC. HE THEN BEGAN FLYING AGAIN AND DSNDED TO FL230. SHORTLY AFTER LEVEL OFF AT FL230 THE ATC CTLR REQUESTED OUR ALT. I RESPONDED 'LEVEL AT FL230.' HE CAME BACK WITH A CLB CLRNC TO FL240, WHICH WE DID. HE SAID HE HAD CLRED US TO FL270!? I THOUGHT I HEARD FL230, AND DUE TO MINOR DISTRS (I.E., SO ON COMPANY RADIO) AND PHYSIOLOGICAL NEED (OF FO TO THE LAVATORY) I WAS THE ONLY ONE WHO HEARD THE CLRNC! SUPPLEMENTAL INFORMATION FROM ACN 244957: IT WAS A EASY AND HONEST MISTAKE, BUT WE ARE STILL UNSURE OF WHO WAS AT FAULT -- ATC OR CAPT, WHO DIDN'T HEAR PROPER READBACK. IN FUTURE I BELIEVE A MINIMUM OF 2 CREW MEMBERS SHOULD HEAR AND CONFIRM ALL ATC INSTRUCTIONS. IF A 2-MAN CREW, MAYBE INSTRUCTIONS SHOULD BE CONFIRMED WITH ATC UPON RETURN OF MISSING CREW MEMBER.

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.