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Flight crew of air carrier medium large transport arriving las mistakes clearance to 11000' as clearance to 10000' and descends too low.
| Attributes | |
| ACN | 138464 |
| Time | |
| Date | 199003 |
| Day | Fri |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : las |
| State Reference | NV |
| Altitude | msl bound lower : 10000 msl bound upper : 11000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | other vortac |
| Flight Phase | cruise other descent other |
| Route In Use | arrival other enroute : on vectors enroute airway : v237 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : flight engineer pilot : atp pilot : commercial pilot : instrument |
| Experience | flight time last 90 days : 280 flight time total : 11800 flight time type : 8000 |
| ASRS Report | 138464 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp pilot : cfi |
| Experience | flight time last 90 days : 260 flight time total : 12000 flight time type : 6000 |
| ASRS Report | 138356 |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : clearance other spatial deviation |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance none taken : detected after the fact |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Frequency was congested and a slightly garbled and weak center transmitter. I thought we had been cleared to 10000'. Captain set 10000' in altitude alert window (he was handling radios) and I descended to 10000'. Informed after level-off that we had been cleared to 11000'. Controller then cleared us to 10000'. I should have asked for verification of assigned altitude because 11000' is normal going into las from the east. However, localizer was OTS, so I thought they were doing something different because the localizer was out. Supplemental information from acn 138356: I am embarrassed and befuddled how 2 competent adults can bust an altitude. I'm sure we were cleared to 11000' and I have no explanation for this altitude deviation. I am usually attentive and conscientious, but I evidently must not be enough. This was a shocking experience for both of us.
Original NASA ASRS Text
Title: FLT CREW OF ACR MLG ARRIVING LAS MISTAKES CLRNC TO 11000' AS CLRNC TO 10000' AND DESCENDS TOO LOW.
Narrative: FREQ WAS CONGESTED AND A SLIGHTLY GARBLED AND WEAK CENTER XMITTER. I THOUGHT WE HAD BEEN CLRED TO 10000'. CAPT SET 10000' IN ALT ALERT WINDOW (HE WAS HANDLING RADIOS) AND I DSNDED TO 10000'. INFORMED AFTER LEVEL-OFF THAT WE HAD BEEN CLRED TO 11000'. CTLR THEN CLRED US TO 10000'. I SHOULD HAVE ASKED FOR VERIFICATION OF ASSIGNED ALT BECAUSE 11000' IS NORMAL GOING INTO LAS FROM THE E. HOWEVER, LOC WAS OTS, SO I THOUGHT THEY WERE DOING SOMETHING DIFFERENT BECAUSE THE LOC WAS OUT. SUPPLEMENTAL INFO FROM ACN 138356: I AM EMBARRASSED AND BEFUDDLED HOW 2 COMPETENT ADULTS CAN BUST AN ALT. I'M SURE WE WERE CLRED TO 11000' AND I HAVE NO EXPLANATION FOR THIS ALT DEVIATION. I AM USUALLY ATTENTIVE AND CONSCIENTIOUS, BUT I EVIDENTLY MUST NOT BE ENOUGH. THIS WAS A SHOCKING EXPERIENCE FOR BOTH OF US.
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.