Narrative:

Center controller gave clearance to descend so as to cross 55 mi north of marvi intersection at FL270. Next controller stated to comply with previous restrs and descend and maintain FL180. My interpretation was that the FL180 clearance was at pilot's discretion after the FL270 restr. That was not what the controller said or wanted. The FMC leveled the aircraft at FL270 and showed 15 NM before the optimum top of descent point. So even though the altitude window had FL180 set in, the aircraft temporarily leveled off. The controller asked what the rate of descent was, and we told him we leveled off at FL270. He said descend to FL180 and turn left heading XXX for radar vectors. He did not say if there was a conflict and after a short vector he turned us back on course and nothing further was mentioned. This resulted from an assumption that the FL180 clearance was discretionary. Neither myself nor the first officer understood it that way because it was not what we expected to hear. The controller was doing his job well and the pilots were not. Even though we read the clearance back correctly, we did not comply with what we read back. When the aircraft leveled off I considered selecting another autoplt mode to continue the descent, but did not. The first officer did not question my actions even though we covered exactly this scenario in our preflight briefing on the first day of trip. First officer was lacking in monitoring and assertiveness and the captain (me) lacked supervision qualities and did not ask the first officer for clarification when something just didn't feel right when I was considering another autoplt mode to continue the descent. (Cockpit resource management not effectively used.)

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Original NASA ASRS Text

Title: ALTDEV ALT UNDERSHOT. FLC OF ACR LEVELED OFF DURING A NON DISCRETIONARY DSCNT.

Narrative: CTR CTLR GAVE CLRNC TO DSND SO AS TO CROSS 55 MI N OF MARVI INTXN AT FL270. NEXT CTLR STATED TO COMPLY WITH PREVIOUS RESTRS AND DSND AND MAINTAIN FL180. MY INTERP WAS THAT THE FL180 CLRNC WAS AT PLT'S DISCRETION AFTER THE FL270 RESTR. THAT WAS NOT WHAT THE CTLR SAID OR WANTED. THE FMC LEVELED THE ACFT AT FL270 AND SHOWED 15 NM BEFORE THE OPTIMUM TOP OF DSCNT POINT. SO EVEN THOUGH THE ALT WINDOW HAD FL180 SET IN, THE ACFT TEMPORARILY LEVELED OFF. THE CTLR ASKED WHAT THE RATE OF DSCNT WAS, AND WE TOLD HIM WE LEVELED OFF AT FL270. HE SAID DSND TO FL180 AND TURN L HDG XXX FOR RADAR VECTORS. HE DID NOT SAY IF THERE WAS A CONFLICT AND AFTER A SHORT VECTOR HE TURNED US BACK ON COURSE AND NOTHING FURTHER WAS MENTIONED. THIS RESULTED FROM AN ASSUMPTION THAT THE FL180 CLRNC WAS DISCRETIONARY. NEITHER MYSELF NOR THE FO UNDERSTOOD IT THAT WAY BECAUSE IT WAS NOT WHAT WE EXPECTED TO HEAR. THE CTLR WAS DOING HIS JOB WELL AND THE PLTS WERE NOT. EVEN THOUGH WE READ THE CLRNC BACK CORRECTLY, WE DID NOT COMPLY WITH WHAT WE READ BACK. WHEN THE ACFT LEVELED OFF I CONSIDERED SELECTING ANOTHER AUTOPLT MODE TO CONTINUE THE DSCNT, BUT DID NOT. THE FO DID NOT QUESTION MY ACTIONS EVEN THOUGH WE COVERED EXACTLY THIS SCENARIO IN OUR PREFLT BRIEFING ON THE FIRST DAY OF TRIP. FO WAS LACKING IN MONITORING AND ASSERTIVENESS AND THE CAPT (ME) LACKED SUPERVISION QUALITIES AND DID NOT ASK THE FO FOR CLARIFICATION WHEN SOMETHING JUST DIDN'T FEEL RIGHT WHEN I WAS CONSIDERING ANOTHER AUTOPLT MODE TO CONTINUE THE DSCNT. (COCKPIT RESOURCE MGMNT NOT EFFECTIVELY USED.)

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.