Narrative:

30 NM west of mol, while at FL350, ZDC cleared us to descend to FL330. We reset the altitude window to FL330 and selected FL330 as cruise altitude in CDU. We had been operating in VNAV but for some unknown reason the aircraft then reverted to altitude hold. I, as the PF, failed to check the ADI for the appropriate descent indications and went about reviewing the arrival procedures for jfk. A min or 2 later, center called and asked if we had received the descent to FL330. I then initiated the descent using flight level change. The flight continued without further incident. Lesson learned: check what is actually on your plate. Supplemental information from acn 409280: we reset the altitude window but failed to notice that we had not engaged the autoplt to start the descent.

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Original NASA ASRS Text

Title: B767 CRUISING AT FL350. CAPT FAILED TO INITIATE DSCNT WHEN CLRED TO LOWER ALT DUE TO UNMONITORED VNAV MALFUNCTION.

Narrative: 30 NM W OF MOL, WHILE AT FL350, ZDC CLRED US TO DSND TO FL330. WE RESET THE ALT WINDOW TO FL330 AND SELECTED FL330 AS CRUISE ALT IN CDU. WE HAD BEEN OPERATING IN VNAV BUT FOR SOME UNKNOWN REASON THE ACFT THEN REVERTED TO ALT HOLD. I, AS THE PF, FAILED TO CHK THE ADI FOR THE APPROPRIATE DSCNT INDICATIONS AND WENT ABOUT REVIEWING THE ARR PROCS FOR JFK. A MIN OR 2 LATER, CTR CALLED AND ASKED IF WE HAD RECEIVED THE DSCNT TO FL330. I THEN INITIATED THE DSCNT USING FLT LEVEL CHANGE. THE FLT CONTINUED WITHOUT FURTHER INCIDENT. LESSON LEARNED: CHK WHAT IS ACTUALLY ON YOUR PLATE. SUPPLEMENTAL INFO FROM ACN 409280: WE RESET THE ALT WINDOW BUT FAILED TO NOTICE THAT WE HAD NOT ENGAGED THE AUTOPLT TO START THE DSCNT.

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.