The FMS failed to make a crossing restriction

Attributes
ACN	272508
Time
Date	199405
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : iah airport : hou
State Reference	TX
Altitude	msl bound lower : 17500 msl bound upper : 17500
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	tower : ewr
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	arrival other arrival star : star enroute airway : hour
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 225 flight time total : 12400 flight time type : 4000
ASRS Report	272508
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 210 flight time total : 11000 flight time type : 4500
ASRS Report	273253
Events
Anomaly	altitude deviation : excursion from assigned altitude altitude deviation : crossing restriction not met altitude deviation : undershoot non adherence : clearance non adherence : published procedure other anomaly other
Independent Detector	other controllera
Resolutory Action	controller : issued new clearance other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I missed the crossing restriction of 10000 ft at 'bumby' on the batsn.BATSN3 arrival to hou. We had been maneuvering around thunderstorms and had received a few routing changes, the latest of which was 'direct to das then to the airport.' as we approached hou, we were cleared direct to bumby and the remainder of the arrival. I started the airplane direct to bumby with the FMS and then inserted the crossing restriction of 10000 ft on the legs page. I then selected the batsn-3 arrival for use by the FMS. What I failed to notice was that by inserting the arrival in the FMS, the computer dumped the crossing restriction I had inserted just a few moments earlier. At this point, I felt comfortable with the position of 'top of descent' point and proceeded to load in the approach to runway 4 (ILS), which had changed from runway 12R with a new ATIS message. At 15 mi prior to the descent point, I started down and intercepted the descent profile well ahead of schedule. During the descent I briefed the approach and set up the navigation for the ILS. Through about 17500 ft, approach control asked if we would make the bumby restriction (10000 ft) and it was immediately obvious that we would not as the descent line we were on no long was using the bumby restriction for computation. The controller stated that it was not a problem and that we should just keep our speed up and proceed on the arrival. The landing was completed without further incident or difficulty. The cause, I believe, was a combination of cockpit management overload during the approach phase coupled with an overconfidence in the FMS to present valid descent profile information. I allowed myself to get too busy during the descent to make essential xchks to confirm the FMS was working as advertised. The correction: always double check the FMS data against other availaable navigation data to insure that your programming is correct and that the aircraft is following accurate FMS guidance. Overconfidence in the FMS and increased workload in the cockpit during bad WX and approach preparation is no excuse for sound pilotage and the maintenance of situational awareness.

Original NASA ASRS Text

Title: THE FMS FAILED TO MAKE A XING RESTRICTION

Narrative: I MISSED THE XING RESTRICTION OF 10000 FT AT 'BUMBY' ON THE BATSN.BATSN3 ARR TO HOU. WE HAD BEEN MANEUVERING AROUND TSTMS AND HAD RECEIVED A FEW ROUTING CHANGES, THE LATEST OF WHICH WAS 'DIRECT TO DAS THEN TO THE ARPT.' AS WE APCHED HOU, WE WERE CLRED DIRECT TO BUMBY AND THE REMAINDER OF THE ARR. I STARTED THE AIRPLANE DIRECT TO BUMBY WITH THE FMS AND THEN INSERTED THE XING RESTRICTION OF 10000 FT ON THE LEGS PAGE. I THEN SELECTED THE BATSN-3 ARR FOR USE BY THE FMS. WHAT I FAILED TO NOTICE WAS THAT BY INSERTING THE ARR IN THE FMS, THE COMPUTER DUMPED THE XING RESTRICTION I HAD INSERTED JUST A FEW MOMENTS EARLIER. AT THIS POINT, I FELT COMFORTABLE WITH THE POS OF 'TOP OF DSCNT' POINT AND PROCEEDED TO LOAD IN THE APCH TO RWY 4 (ILS), WHICH HAD CHANGED FROM RWY 12R WITH A NEW ATIS MESSAGE. AT 15 MI PRIOR TO THE DSCNT POINT, I STARTED DOWN AND INTERCEPTED THE DSCNT PROFILE WELL AHEAD OF SCHEDULE. DURING THE DSCNT I BRIEFED THE APCH AND SET UP THE NAV FOR THE ILS. THROUGH ABOUT 17500 FT, APCH CTL ASKED IF WE WOULD MAKE THE BUMBY RESTRICTION (10000 FT) AND IT WAS IMMEDIATELY OBVIOUS THAT WE WOULD NOT AS THE DSCNT LINE WE WERE ON NO LONG WAS USING THE BUMBY RESTRICTION FOR COMPUTATION. THE CTLR STATED THAT IT WAS NOT A PROB AND THAT WE SHOULD JUST KEEP OUR SPD UP AND PROCEED ON THE ARR. THE LNDG WAS COMPLETED WITHOUT FURTHER INCIDENT OR DIFFICULTY. THE CAUSE, I BELIEVE, WAS A COMBINATION OF COCKPIT MGMNT OVERLOAD DURING THE APCH PHASE COUPLED WITH AN OVERCONFIDENCE IN THE FMS TO PRESENT VALID DSCNT PROFILE INFO. I ALLOWED MYSELF TO GET TOO BUSY DURING THE DSCNT TO MAKE ESSENTIAL XCHKS TO CONFIRM THE FMS WAS WORKING AS ADVERTISED. THE CORRECTION: ALWAYS DOUBLE CHK THE FMS DATA AGAINST OTHER AVAILAABLE NAV DATA TO INSURE THAT YOUR PROGRAMMING IS CORRECT AND THAT THE ACFT IS FOLLOWING ACCURATE FMS GUIDANCE. OVERCONFIDENCE IN THE FMS AND INCREASED WORKLOAD IN THE COCKPIT DURING BAD WX AND APCH PREPARATION IS NO EXCUSE FOR SOUND PILOTAGE AND THE MAINT OF SITUATIONAL AWARENESS.

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.