 |
37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Unnoticed by the crew; a B737-800's FMS reverted to vertical speed from VNAV and subsequently the aircraft missed a STAR altitude constraint. CRM was an issue.
| Attributes | |
| ACN | 720853 |
| Time | |
| Date | 200612 |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | intersection : trtle |
| State Reference | CA |
| Altitude | msl single value : 14500 |
| Environment | |
| Flight Conditions | IMC |
| Weather Elements | Ice |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | tracon : sct.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | B737-800 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent : intermediate altitude |
| Route In Use | arrival star : seavu1 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | aircraft equipment problem : less severe altitude deviation : crossing restriction not met non adherence : clearance |
| Independent Detector | other flight crewa |
| Resolutory Action | none taken : detected after the fact |
| Supplementary | |
| Problem Areas | Aircraft Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
Narrative:
ATC cleared us to descend via the seavu; SEAVU1 arrival approximately west of the konzl fix. The next altitude restr was at the trtle fix between 17000 ft and 16000 ft. We crossed trtle at approximately 14500 ft. While setting up the arrival; I was unaware that VNAV dropped and reverted to vertical speed. I disconnected the autoplt and maneuvered to make the next restr at the cataw fix. The rest of the arrival and approach were flown without incident. 2 contributing factors were: 1) relative newness to the B737-800 (4 months) on my part. That is something that should always be crosschecked on a VNAV descent and that is not yet in my habit pattern. My previous aircraft was the B737-200 which had no VNAV capability. 2) there was a definite personality clash in the cockpit that served as a major distraction for me and obviously my copilot since he was not backing me up and did not notice the error until after I disconnected the autoplt.
Original NASA ASRS Text
Title: UNNOTICED BY THE CREW; A B737-800'S FMS REVERTED TO VERT SPD FROM VNAV AND SUBSEQUENTLY THE ACFT MISSED A STAR ALT CONSTRAINT. CRM WAS AN ISSUE.
Narrative: ATC CLRED US TO DSND VIA THE SEAVU; SEAVU1 ARR APPROX W OF THE KONZL FIX. THE NEXT ALT RESTR WAS AT THE TRTLE FIX BTWN 17000 FT AND 16000 FT. WE CROSSED TRTLE AT APPROX 14500 FT. WHILE SETTING UP THE ARR; I WAS UNAWARE THAT VNAV DROPPED AND REVERTED TO VERT SPD. I DISCONNECTED THE AUTOPLT AND MANEUVERED TO MAKE THE NEXT RESTR AT THE CATAW FIX. THE REST OF THE ARR AND APCH WERE FLOWN WITHOUT INCIDENT. 2 CONTRIBUTING FACTORS WERE: 1) RELATIVE NEWNESS TO THE B737-800 (4 MONTHS) ON MY PART. THAT IS SOMETHING THAT SHOULD ALWAYS BE XCHKED ON A VNAV DSCNT AND THAT IS NOT YET IN MY HABIT PATTERN. MY PREVIOUS ACFT WAS THE B737-200 WHICH HAD NO VNAV CAPABILITY. 2) THERE WAS A DEFINITE PERSONALITY CLASH IN THE COCKPIT THAT SERVED AS A MAJOR DISTR FOR ME AND OBVIOUSLY MY COPLT SINCE HE WAS NOT BACKING ME UP AND DID NOT NOTICE THE ERROR UNTIL AFTER I DISCONNECTED THE AUTOPLT.
Data retrieved from NASA's ASRS site as of January 2009 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.