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37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
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Flight crew of air carrier medium large transport aircraft overshot assigned descent crossing altitude due to a misunderstanding of ATC clearance.
| Attributes | |
| ACN | 227692 |
| Time | |
| Date | 199211 |
| Day | Wed |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : vuz |
| State Reference | AL |
| Altitude | msl bound lower : 11000 msl bound upper : 12000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : abi |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Route In Use | enroute airway : cbm |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | other |
| Make Model Name | Military Transport |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 200 flight time total : 15000 flight time type : 800 |
| ASRS Report | 227692 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : flight engineer pilot : instrument |
| Experience | flight time last 90 days : 200 flight time total : 2000 flight time type : 310 |
| ASRS Report | 227112 |
| Events | |
| Anomaly | altitude deviation : overshoot conflict : airborne less severe non adherence : clearance |
| Independent Detector | atc equipment other atc equipment : unspecified other controllera |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Miss Distance | horizontal : 18000 vertical : 200 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | other |
Narrative:
At 33000 we were given a descent to maintain 11000. Then asked to 'be at 12000 ft in 24 mi.' ATC request us to slow to 250 KTS. We told them that the 24 mi restriction would not be kept at 250 KTS. We were then told to make it 30 mi from our present position, then slow to 250. (By the way 12000 in 24/30 was said, both the first officer and myself felt it was a crossing restriction). After leveling at 11000 ATC called traffic at 10 O'clock 10 mi. We had the traffic in sight and told to maintain visual separation. The closest we came was 200 ft vertical 3 mi horizontal. At no time were we told to maintain 12000 ft when the clearance altitude changes I think the term 'maintain' should be included in the statement.
Original NASA ASRS Text
Title: FLC OF ACR MLG ACFT OVERSHOT ASSIGNED DSCNT XING ALT DUE TO A MISUNDERSTANDING OF ATC CLRNC.
Narrative: AT 33000 WE WERE GIVEN A DSCNT TO MAINTAIN 11000. THEN ASKED TO 'BE AT 12000 FT IN 24 MI.' ATC REQUEST US TO SLOW TO 250 KTS. WE TOLD THEM THAT THE 24 MI RESTRICTION WOULD NOT BE KEPT AT 250 KTS. WE WERE THEN TOLD TO MAKE IT 30 MI FROM OUR PRESENT POS, THEN SLOW TO 250. (BY THE WAY 12000 IN 24/30 WAS SAID, BOTH THE FO AND MYSELF FELT IT WAS A XING RESTRICTION). AFTER LEVELING AT 11000 ATC CALLED TFC AT 10 O'CLOCK 10 MI. WE HAD THE TFC IN SIGHT AND TOLD TO MAINTAIN VISUAL SEPARATION. THE CLOSEST WE CAME WAS 200 FT VERT 3 MI HORIZ. AT NO TIME WERE WE TOLD TO MAINTAIN 12000 FT WHEN THE CLRNC ALT CHANGES I THINK THE TERM 'MAINTAIN' SHOULD BE INCLUDED IN THE STATEMENT.
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.