Flight crew of a B737-400 failed to cross altitude fix at assigned altitude resulting in ATC interve...

Attributes
ACN	402440
Time
Date	199805
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : dny
State Reference	NY
Altitude	msl bound lower : 19000 msl bound upper : 24000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny tower : clt
Operator	common carrier : air carrier
Make Model Name	B737-400
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other
Route In Use	enroute airway : zny
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 13200 flight time type : 6500
ASRS Report	402440
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : crossing restriction not met non adherence : clearance
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Cruising at FL240, ATC issued 'cross 15 mi south of dny at FL190.' I read back clearance. First officer (PF) entered crossing restr in FMC. A few mins after that, first officer made PA to passenger. As he started PA I went to descent page on FMC. I noticed we still had 24 mi until top of descent. All I looked at was just that, and not top of descent for 15 mi south of dny. Turns out 24000 ft until top of descent was for next waypoint down the road. Just about the time we realized the problem, ATC inquired when we would begin our descent. I replied 'not for a little while yet.' I was still thinking we had a few more mi yet. However, an inquiry from ATC about your altitude usually sends a jolt of adrenaline and we both checked our distance from dny. To our shock, we were about 20 mi south, already past the crossing restr, and still at FL240. ATC then issued the following, 'just cross lhy at 12000 ft.' nothing further was said about it between ATC and us. After reflecting on the incident, the first officer and I thought the only possible scenario was the FMC dumped the data because it was entered properly, VNAV was engaged, and it is possible that the data was lost because it couldn't 'make' the descent. This is the first time this has ever happened to me and other than the fact I should have monitored better, I have never seen an FMS do that. Now I monitor better and check it again before allowing and trusting a computer to do it.

Original NASA ASRS Text

Title: FLC OF A B737-400 FAILED TO CROSS ALT FIX AT ASSIGNED ALT RESULTING IN ATC INTERVENTION TO REMIND RPTR THAT THE FIX HAD BEEN OVERSHOT. ATC AMENDED CLRNC FOR OTHER ALT XING FIXES.

Narrative: CRUISING AT FL240, ATC ISSUED 'CROSS 15 MI S OF DNY AT FL190.' I READ BACK CLRNC. FO (PF) ENTERED XING RESTR IN FMC. A FEW MINS AFTER THAT, FO MADE PA TO PAX. AS HE STARTED PA I WENT TO DSCNT PAGE ON FMC. I NOTICED WE STILL HAD 24 MI UNTIL TOP OF DSCNT. ALL I LOOKED AT WAS JUST THAT, AND NOT TOP OF DSCNT FOR 15 MI S OF DNY. TURNS OUT 24000 FT UNTIL TOP OF DSCNT WAS FOR NEXT WAYPOINT DOWN THE ROAD. JUST ABOUT THE TIME WE REALIZED THE PROB, ATC INQUIRED WHEN WE WOULD BEGIN OUR DSCNT. I REPLIED 'NOT FOR A LITTLE WHILE YET.' I WAS STILL THINKING WE HAD A FEW MORE MI YET. HOWEVER, AN INQUIRY FROM ATC ABOUT YOUR ALT USUALLY SENDS A JOLT OF ADRENALINE AND WE BOTH CHKED OUR DISTANCE FROM DNY. TO OUR SHOCK, WE WERE ABOUT 20 MI S, ALREADY PAST THE XING RESTR, AND STILL AT FL240. ATC THEN ISSUED THE FOLLOWING, 'JUST CROSS LHY AT 12000 FT.' NOTHING FURTHER WAS SAID ABOUT IT BTWN ATC AND US. AFTER REFLECTING ON THE INCIDENT, THE FO AND I THOUGHT THE ONLY POSSIBLE SCENARIO WAS THE FMC DUMPED THE DATA BECAUSE IT WAS ENTERED PROPERLY, VNAV WAS ENGAGED, AND IT IS POSSIBLE THAT THE DATA WAS LOST BECAUSE IT COULDN'T 'MAKE' THE DSCNT. THIS IS THE FIRST TIME THIS HAS EVER HAPPENED TO ME AND OTHER THAN THE FACT I SHOULD HAVE MONITORED BETTER, I HAVE NEVER SEEN AN FMS DO THAT. NOW I MONITOR BETTER AND CHK IT AGAIN BEFORE ALLOWING AND TRUSTING A COMPUTER TO DO IT.

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.

Flight crew of a B737-400 failed to cross altitude fix at assigned altitude resulting in ATC intervention to remind reporter that the fix had been overshot. ATC amended clearance for other altitude crossing fixes.