Narrative:

On aug/thu/89, I was the captain on an large transport air carrier flight xx, lga-dtw. Our routing was the lga 3 SID out of lga to neon intersection J95 to kooper dir aylmer V-2 rhyme dir dtw airport. We were en route from kooper to aylmer at FL350 and were cleared to cross 15 east of aylmer at FL310. We programmed 15 east of aylmer at 310 in the FMC and set 310 in the mode control panel. A 'top of descent' circle showed up on the screen depicting where the descent would begin. However, at the top of descent pt, the aircraft did not descend and due to distracting conversation between us, neither I nor the first officer noticed it until we were about 20 mi east of aylmer. I immediately started a fairly rapid descent of about 4000 FPM with speed brakes and saw we were not going to make 15 east aylmer at FL310. I called cle and said we started down too late and were not going to make 15 east aylmer at 310. In fact, we were crossing 15 east aylmer at 330. Cle said that's ok and gave us a frequency change. I don't know why, with everything apparently set in properly, the aircraft did not descend at the proper time. I feel the cause of this mistake is too much reliance on automated systems and a lack of vigilance on my part as to the altitude and position of my aircraft.

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Original NASA ASRS Text

Title: ALT DEVIATION UNDERSHOOT IN DESCENT. REPORTER REQUESTS NO CALLBACK.

Narrative: ON AUG/THU/89, I WAS THE CAPT ON AN LGT ACR FLT XX, LGA-DTW. OUR ROUTING WAS THE LGA 3 SID OUT OF LGA TO NEON INTXN J95 TO KOOPER DIR AYLMER V-2 RHYME DIR DTW ARPT. WE WERE ENRTE FROM KOOPER TO AYLMER AT FL350 AND WERE CLRED TO CROSS 15 E OF AYLMER AT FL310. WE PROGRAMMED 15 E OF AYLMER AT 310 IN THE FMC AND SET 310 IN THE MODE CTL PANEL. A 'TOP OF DESCENT' CIRCLE SHOWED UP ON THE SCREEN DEPICTING WHERE THE DESCENT WOULD BEGIN. HOWEVER, AT THE TOP OF DESCENT PT, THE ACFT DID NOT DESCEND AND DUE TO DISTRACTING CONVERSATION BETWEEN US, NEITHER I NOR THE F/O NOTICED IT UNTIL WE WERE ABOUT 20 MI E OF AYLMER. I IMMEDIATELY STARTED A FAIRLY RAPID DESCENT OF ABOUT 4000 FPM WITH SPEED BRAKES AND SAW WE WERE NOT GOING TO MAKE 15 E AYLMER AT FL310. I CALLED CLE AND SAID WE STARTED DOWN TOO LATE AND WERE NOT GOING TO MAKE 15 E AYLMER AT 310. IN FACT, WE WERE XING 15 E AYLMER AT 330. CLE SAID THAT'S OK AND GAVE US A FREQ CHANGE. I DON'T KNOW WHY, WITH EVERYTHING APPARENTLY SET IN PROPERLY, THE ACFT DID NOT DESCEND AT THE PROPER TIME. I FEEL THE CAUSE OF THIS MISTAKE IS TOO MUCH RELIANCE ON AUTOMATED SYSTEMS AND A LACK OF VIGILANCE ON MY PART AS TO THE ALT AND POSITION OF MY ACFT.

Data retrieved from NASA's ASRS site as of August 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.