Narrative:

We were flying a widebody transport with the latest glass cockpit including moving map display and computerized VNAV, etc. We were descending to land at dtw and had been given an expected crossing restriction of 40 east of mkg at FL230. I was flying the aircraft and the first officer was handling radios and programming the flight management computer (FMC) which includes the VNAV. The first officer programmed the crossing restriction into the FMC VNAV. He entered it out of sequence (after, rather then before the next chkpoint). This caused an incorrect prediction of the point at which we would reach the altitude. The crossing point was displayed in a confusing manner and I never idented it until we were too close to make the restriction. I had asked him to clarify his point but both of us were busy with our normal duties. We were given several altitude changes and I was concentrating on flying the aircraft and leveling out at the correct altitude. The last one was FL250. At approximately 31000-32000' in descent and 10 mi from the fix, the ATC controller finally give us a clearance to cross the 40 mi point east of mkg at FL230. There was no way the aircraft could make that restriction. The controller called and asked why we didn't comply with the restriction. I feel that this incident happened because the ATC controller overloaded us with altitude changes and withheld the crossing restriction until the very last min. Even if we had been level at FL250, then given the restriction it would have been nearly impossible to make it. A contributing factor was the complexity of the FMC programming and depiction on the moving map display. Supplemental information from acn 150650. The expect FL230 was repeated twice more at several min intervals. At 10 mi from the 40 DME fix, clearance to cross 40 DME at FL230 was given and acknowledged by me. The result was the trend indicator of when we would cross that FL230 altitude was incorrectly interpreted. We thought we had more distance to descend. A second factor was not backing the computer generated information with raw data. At the fix, plus 10 mi we were 6800' high and advised by chicago center we were at the fix and had not complied with the constraint.

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Original NASA ASRS Text

Title: ALT DEVIATION, ALT CROSSING RESTRICTION NOT MET BY ADVANCED 4 ENGINED WDB.

Narrative: WE WERE FLYING A WDB WITH THE LATEST GLASS COCKPIT INCLUDING MOVING MAP DISPLAY AND COMPUTERIZED VNAV, ETC. WE WERE DSNDING TO LAND AT DTW AND HAD BEEN GIVEN AN EXPECTED XING RESTRICTION OF 40 E OF MKG AT FL230. I WAS FLYING THE ACFT AND THE F/O WAS HANDLING RADIOS AND PROGRAMMING THE FLT MGMNT COMPUTER (FMC) WHICH INCLUDES THE VNAV. THE F/O PROGRAMMED THE XING RESTRICTION INTO THE FMC VNAV. HE ENTERED IT OUT OF SEQUENCE (AFTER, RATHER THEN BEFORE THE NEXT CHKPOINT). THIS CAUSED AN INCORRECT PREDICTION OF THE POINT AT WHICH WE WOULD REACH THE ALT. THE XING POINT WAS DISPLAYED IN A CONFUSING MANNER AND I NEVER IDENTED IT UNTIL WE WERE TOO CLOSE TO MAKE THE RESTRICTION. I HAD ASKED HIM TO CLARIFY HIS POINT BUT BOTH OF US WERE BUSY WITH OUR NORMAL DUTIES. WE WERE GIVEN SEVERAL ALT CHANGES AND I WAS CONCENTRATING ON FLYING THE ACFT AND LEVELING OUT AT THE CORRECT ALT. THE LAST ONE WAS FL250. AT APPROX 31000-32000' IN DSNT AND 10 MI FROM THE FIX, THE ATC CTLR FINALLY GIVE US A CLRNC TO CROSS THE 40 MI POINT E OF MKG AT FL230. THERE WAS NO WAY THE ACFT COULD MAKE THAT RESTRICTION. THE CTLR CALLED AND ASKED WHY WE DIDN'T COMPLY WITH THE RESTRICTION. I FEEL THAT THIS INCIDENT HAPPENED BECAUSE THE ATC CTLR OVERLOADED US WITH ALT CHANGES AND WITHHELD THE XING RESTRICTION UNTIL THE VERY LAST MIN. EVEN IF WE HAD BEEN LEVEL AT FL250, THEN GIVEN THE RESTRICTION IT WOULD HAVE BEEN NEARLY IMPOSSIBLE TO MAKE IT. A CONTRIBUTING FACTOR WAS THE COMPLEXITY OF THE FMC PROGRAMMING AND DEPICTION ON THE MOVING MAP DISPLAY. SUPPLEMENTAL INFO FROM ACN 150650. THE EXPECT FL230 WAS REPEATED TWICE MORE AT SEVERAL MIN INTERVALS. AT 10 MI FROM THE 40 DME FIX, CLRNC TO CROSS 40 DME AT FL230 WAS GIVEN AND ACKNOWLEDGED BY ME. THE RESULT WAS THE TREND INDICATOR OF WHEN WE WOULD CROSS THAT FL230 ALT WAS INCORRECTLY INTERPRETED. WE THOUGHT WE HAD MORE DISTANCE TO DSND. A SECOND FACTOR WAS NOT BACKING THE COMPUTER GENERATED INFO WITH RAW DATA. AT THE FIX, PLUS 10 MI WE WERE 6800' HIGH AND ADVISED BY CHICAGO CTR WE WERE AT THE FIX AND HAD NOT COMPLIED WITH THE CONSTRAINT.

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.