Narrative:

During a routine flight we were cleared direct to lamma intersection on the bitho 6 arrival into orl. The arrival states to 'expect to cross lamma intersection at 12000 ft.' consequently, I programmed the FMC to cross lamma intersection at 12000 ft. Prior to receiving a descent clearance the aircraft began to descend based on the computer top of descent point. The captain, who had left the cockpit for physiological reasons, was just getting back into his seat. ZJX then asked us what our altitude was. At this time I realized we were never cleared to leave FL310 and hence, started a climb back to FL310. The controller then cleared us to cross lamma intersection at 12000 ft. When asked about the altitude deviation the controller stated, 'don't worry about it.' the contributing factors to this event are as follows. The crew flew to same destination all month and was routinely cleared to cross a fix at same altitude. We were preprogrammed mentally for such action. A 2-MAN cockpit lends itself to errors when no backup is available if 1 of the crew leaves the cockpit. The pilot with low time operating experience in a sophisticated aircraft that is computer operated inadvertently programmed computer improperly. 3 areas that may be considered to prevent this from happening are re-word altitude crossing restrs on departure and arrs such as: eliminate the phrase 'expect to cross at' and replace with 'cross at, only if radio contact failure.' re-examine company procedures with regard to programming FMC's. Analyze aim procedures with regard to clrncs given to 2-MAN crews when 1 crew member is out of the cockpit.

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Original NASA ASRS Text

Title: FMC PROGRAMMED FOR AN 'EXPECT' CLRNC BEGAN DSCNT PRIOR TO ACTUAL ATC CLRNC. CTLR INTERVENED.

Narrative: DURING A ROUTINE FLT WE WERE CLRED DIRECT TO LAMMA INTXN ON THE BITHO 6 ARR INTO ORL. THE ARR STATES TO 'EXPECT TO CROSS LAMMA INTXN AT 12000 FT.' CONSEQUENTLY, I PROGRAMMED THE FMC TO CROSS LAMMA INTXN AT 12000 FT. PRIOR TO RECEIVING A DSCNT CLRNC THE ACFT BEGAN TO DSND BASED ON THE COMPUTER TOP OF DSCNT POINT. THE CAPT, WHO HAD LEFT THE COCKPIT FOR PHYSIOLOGICAL REASONS, WAS JUST GETTING BACK INTO HIS SEAT. ZJX THEN ASKED US WHAT OUR ALT WAS. AT THIS TIME I REALIZED WE WERE NEVER CLRED TO LEAVE FL310 AND HENCE, STARTED A CLB BACK TO FL310. THE CTLR THEN CLRED US TO CROSS LAMMA INTXN AT 12000 FT. WHEN ASKED ABOUT THE ALTDEV THE CTLR STATED, 'DON'T WORRY ABOUT IT.' THE CONTRIBUTING FACTORS TO THIS EVENT ARE AS FOLLOWS. THE CREW FLEW TO SAME DEST ALL MONTH AND WAS ROUTINELY CLRED TO CROSS A FIX AT SAME ALT. WE WERE PREPROGRAMMED MENTALLY FOR SUCH ACTION. A 2-MAN COCKPIT LENDS ITSELF TO ERRORS WHEN NO BACKUP IS AVAILABLE IF 1 OF THE CREW LEAVES THE COCKPIT. THE PLT WITH LOW TIME OPERATING EXPERIENCE IN A SOPHISTICATED ACFT THAT IS COMPUTER OPERATED INADVERTENTLY PROGRAMMED COMPUTER IMPROPERLY. 3 AREAS THAT MAY BE CONSIDERED TO PREVENT THIS FROM HAPPENING ARE RE-WORD ALT XING RESTRS ON DEP AND ARRS SUCH AS: ELIMINATE THE PHRASE 'EXPECT TO CROSS AT' AND REPLACE WITH 'CROSS AT, ONLY IF RADIO CONTACT FAILURE.' RE-EXAMINE COMPANY PROCS WITH REGARD TO PROGRAMMING FMC'S. ANALYZE AIM PROCS WITH REGARD TO CLRNCS GIVEN TO 2-MAN CREWS WHEN 1 CREW MEMBER IS OUT OF THE COCKPIT.

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.