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A B757 flight crew relied on the FMC and crossed a fix below the required altitude. This potential error was ignored by a crew member after it was brought to attention.
| Attributes | |
| ACN | 450420 |
| Time | |
| Date | 199909 |
| Day | Wed |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | navaid : pdz.vor |
| State Reference | CA |
| Altitude | msl single value : 17000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zla.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | descent : approach |
| Route In Use | arrival star : pdz 3 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : flight engineer pilot : instrument pilot : multi engine |
| Experience | flight time last 90 days : 225 flight time total : 10210 flight time type : 1290 |
| ASRS Report | 450420 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance non adherence : published procedure |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | none taken : anomaly accepted |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Descending on the pdz 3 arrival to lax to cross konzl at 17000 ft. Captain had just entered a speed reduction to 250 KTS in the FMS and it apparently was a little 'behind' the aircraft. I pointed out to the captain that we looked like we would be low at konzl intersection, but he didn't feel the deviation was big enough to intervene on the MCP or to disconnect. As a result, we passed through 17000 ft about 2 mi prior to konzl and leveled at 16000 ft for trtle intersection. By this time, the FMS had 'caught up' again and VNAV'ed the rest of the arrival without problem. The biggest contributing factor was a captain who had recently returned from a lengthy sick leave (over 1 yr) and isn't 100% proficient yet with the FMC, and was probably getting a little tired hearing recommendations/corrections to FMS inputs from his first officer.
Original NASA ASRS Text
Title: A B757 FLC RELIED ON THE FMC AND CROSSED A FIX BELOW THE REQUIRED ALT. THIS POTENTIAL ERROR WAS IGNORED BY A CREW MEMBER AFTER IT WAS BROUGHT TO ATTN.
Narrative: DSNDING ON THE PDZ 3 ARR TO LAX TO CROSS KONZL AT 17000 FT. CAPT HAD JUST ENTERED A SPD REDUCTION TO 250 KTS IN THE FMS AND IT APPARENTLY WAS A LITTLE 'BEHIND' THE ACFT. I POINTED OUT TO THE CAPT THAT WE LOOKED LIKE WE WOULD BE LOW AT KONZL INTXN, BUT HE DIDN'T FEEL THE DEV WAS BIG ENOUGH TO INTERVENE ON THE MCP OR TO DISCONNECT. AS A RESULT, WE PASSED THROUGH 17000 FT ABOUT 2 MI PRIOR TO KONZL AND LEVELED AT 16000 FT FOR TRTLE INTXN. BY THIS TIME, THE FMS HAD 'CAUGHT UP' AGAIN AND VNAV'ED THE REST OF THE ARR WITHOUT PROB. THE BIGGEST CONTRIBUTING FACTOR WAS A CAPT WHO HAD RECENTLY RETURNED FROM A LENGTHY SICK LEAVE (OVER 1 YR) AND ISN'T 100% PROFICIENT YET WITH THE FMC, AND WAS PROBABLY GETTING A LITTLE TIRED HEARING RECOMMENDATIONS/CORRECTIONS TO FMS INPUTS FROM HIS FO.
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.