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Flight crew of a B737 overshot descent assigned altitude due to incorrect altitude given by controller. Both flight crew members acknowledged altitude, but thought it was an inappropriate altitude for their direction of flight. ATC intervened and observed them go beyond the altitude at which ATC really was thinking.
| Attributes | |
| ACN | 391704 |
| Time | |
| Date | 199801 |
| Day | Sat |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : dvc |
| State Reference | CO |
| Altitude | msl bound lower : 25000 msl bound upper : 28000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | other other : other pilot : atp pilot : instrument pilot : commercial |
| Experience | flight time last 90 days : 250 flight time total : 5500 flight time type : 2000 |
| ASRS Report | 391704 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 260 flight time total : 11000 flight time type : 5000 |
| ASRS Report | 392280 |
| Events | |
| Anomaly | altitude deviation : overshoot other anomaly other |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | other |
Narrative:
We were flying along at FL310, experiencing light turbulence, and requested lower. ZDV then assigned us FL250. As we were descending through approximately 26000 ft, they asked us our assigned altitude. We had read back FL250 earlier, and repeated that to them. He said that he assigned us FL280. We leveled off at FL250 and he said to stay there. We (both pilots) heard FL250 as our assigned altitude, and read it back that way. We believe ZDV assigned us FL250 in error, but we did as we were told. There were no apparent traffic conflicts as a result. The ZDV controller was very busy at the time due to numerous aircraft requesting lower altitudes due to turbulence. We earlier questioned (in the cockpit) why he assigned us FL250 vice FL280 or FL260 (proper cruising altitude for our wbound course), but not on the radio to him. He (ZDV), 5 mins later, had 2 other aircraft talk to him about 'what flight level' they were assigned, etc. I believe the controller was task saturated and could not handle the volume of aircraft at that certain time. This occurred at XX00Z, frequency 128.12 near dove creek VOR (dvc).
Original NASA ASRS Text
Title: FLC OF A B737 OVERSHOT DSCNT ASSIGNED ALT DUE TO INCORRECT ALT GIVEN BY CTLR. BOTH FLC MEMBERS ACKNOWLEDGED ALT, BUT THOUGHT IT WAS AN INAPPROPRIATE ALT FOR THEIR DIRECTION OF FLT. ATC INTERVENED AND OBSERVED THEM GO BEYOND THE ALT AT WHICH ATC REALLY WAS THINKING.
Narrative: WE WERE FLYING ALONG AT FL310, EXPERIENCING LIGHT TURB, AND REQUESTED LOWER. ZDV THEN ASSIGNED US FL250. AS WE WERE DSNDING THROUGH APPROX 26000 FT, THEY ASKED US OUR ASSIGNED ALT. WE HAD READ BACK FL250 EARLIER, AND REPEATED THAT TO THEM. HE SAID THAT HE ASSIGNED US FL280. WE LEVELED OFF AT FL250 AND HE SAID TO STAY THERE. WE (BOTH PLTS) HEARD FL250 AS OUR ASSIGNED ALT, AND READ IT BACK THAT WAY. WE BELIEVE ZDV ASSIGNED US FL250 IN ERROR, BUT WE DID AS WE WERE TOLD. THERE WERE NO APPARENT TFC CONFLICTS AS A RESULT. THE ZDV CTLR WAS VERY BUSY AT THE TIME DUE TO NUMEROUS ACFT REQUESTING LOWER ALTS DUE TO TURB. WE EARLIER QUESTIONED (IN THE COCKPIT) WHY HE ASSIGNED US FL250 VICE FL280 OR FL260 (PROPER CRUISING ALT FOR OUR WBOUND COURSE), BUT NOT ON THE RADIO TO HIM. HE (ZDV), 5 MINS LATER, HAD 2 OTHER ACFT TALK TO HIM ABOUT 'WHAT FLT LEVEL' THEY WERE ASSIGNED, ETC. I BELIEVE THE CTLR WAS TASK SATURATED AND COULD NOT HANDLE THE VOLUME OF ACFT AT THAT CERTAIN TIME. THIS OCCURRED AT XX00Z, FREQ 128.12 NEAR DOVE CREEK VOR (DVC).
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.