B737 crew did not comply with an ATC issued crossing restr.

Attributes
ACN	465113
Time
Date	200002
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : zizzi
State Reference	NJ
Altitude	msl single value : 18000
Environment
Flight Conditions	Marginal
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : vacating altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 230 flight time total : 9200 flight time type : 760
ASRS Report	465113
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : crossing restriction not met non adherence : clearance
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While flying southwest along J-174 approaching zizzi intersection at FL260, we were directed by ZDC to descend and cross the zizzi intersection at FL180. We acknowledged the clearance, set FL180 in the MCP and I, as the PF, programmed the FMC to cross zizzi intersection at FL180. Since we weren't yet at the computed top of descent point, I elected to capture the programmed descent profile and the aircraft started at 1000 FPM descent. I checked the programmed descent, verified VNAV and LNAV captured on the mode annunciator panel, and assumed the FMC would fly the aircraft to reach zizzi intersection at FL180. Approximately 3 mins later, the captain saw that the FMC did not increase rate of descent at the top of descent point. We retarded the throttles to flight idle and deployed the speed brake while notifying ATC that we might not make zizzi at FL180. Neither of us know why the FMC did not descend properly as it was programmed and confirmed by both pilots. We reached FL180 approximately 2 NM southwest of zizzi without traffic conflict. I'm trying to get an answer from the training department as to why the FMC did not follow the programmed descent.

Original NASA ASRS Text

Title: B737 CREW DID NOT COMPLY WITH AN ATC ISSUED XING RESTR.

Narrative: WHILE FLYING SW ALONG J-174 APCHING ZIZZI INTXN AT FL260, WE WERE DIRECTED BY ZDC TO DSND AND CROSS THE ZIZZI INTXN AT FL180. WE ACKNOWLEDGED THE CLRNC, SET FL180 IN THE MCP AND I, AS THE PF, PROGRAMMED THE FMC TO CROSS ZIZZI INTXN AT FL180. SINCE WE WEREN'T YET AT THE COMPUTED TOP OF DSCNT POINT, I ELECTED TO CAPTURE THE PROGRAMMED DSCNT PROFILE AND THE ACFT STARTED AT 1000 FPM DSCNT. I CHKED THE PROGRAMMED DSCNT, VERIFIED VNAV AND LNAV CAPTURED ON THE MODE ANNUNCIATOR PANEL, AND ASSUMED THE FMC WOULD FLY THE ACFT TO REACH ZIZZI INTXN AT FL180. APPROX 3 MINS LATER, THE CAPT SAW THAT THE FMC DID NOT INCREASE RATE OF DSCNT AT THE TOP OF DSCNT POINT. WE RETARDED THE THROTTLES TO FLT IDLE AND DEPLOYED THE SPD BRAKE WHILE NOTIFYING ATC THAT WE MIGHT NOT MAKE ZIZZI AT FL180. NEITHER OF US KNOW WHY THE FMC DID NOT DSND PROPERLY AS IT WAS PROGRAMMED AND CONFIRMED BY BOTH PLTS. WE REACHED FL180 APPROX 2 NM SW OF ZIZZI WITHOUT TFC CONFLICT. I'M TRYING TO GET AN ANSWER FROM THE TRAINING DEPT AS TO WHY THE FMC DID NOT FOLLOW THE PROGRAMMED 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.