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A hearback readback problem resulting in a descent form FL220 to FL200 and a possible loss of separation.
| Attributes | |
| ACN | 136346 |
| Time | |
| Date | 199002 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : hdn |
| State Reference | CO |
| Altitude | msl bound lower : 20000 msl bound upper : 22000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdv |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport |
| Flight Phase | cruise other descent 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 : 20000 flight time type : 3000 |
| ASRS Report | 136346 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude conflict : airborne less severe other anomaly other |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance other |
| Consequence | faa : reviewed incident with flight crew |
| Supplementary | |
| Primary Problem | Ambiguous |
| Air Traffic Incident | other |
Narrative:
While approaching hayden, co (our destination), ZDV gave us a descent clearance to FL200 (we thought) with an EAC of 2000'. Our altitude at the time was FL220. The first officer read back the clearance 'cleared to FL200,' and we started the descent. While descending through FL210, the center inquired as to our altitude and we reported leaving 'FL210 for FL200.' at that time the center controller informed us that we should be maintaining FL220 and gave us an immediate climb and turn to avoid traffic at FL210. Upon reaching FL220 we were then informed we may have busted an altitude and were given the phone # of the den ARTCC. We suggested the controller replay the voice tape and check our readback 'to FL200.' this was done. The watch supervisor told me we were cleared to maintain FL220, but read back FL200 and the controller missed the readback, so the matter would be handled internally at the center and he doubted we would hear anymore about it.
Original NASA ASRS Text
Title: A HEARBACK READBACK PROBLEM RESULTING IN A DESCENT FORM FL220 TO FL200 AND A POSSIBLE LOSS OF SEPARATION.
Narrative: WHILE APCHING HAYDEN, CO (OUR DEST), ZDV GAVE US A DSCNT CLRNC TO FL200 (WE THOUGHT) WITH AN EAC OF 2000'. OUR ALT AT THE TIME WAS FL220. THE F/O READ BACK THE CLRNC 'CLRED TO FL200,' AND WE STARTED THE DSCNT. WHILE DSNDING THROUGH FL210, THE CENTER INQUIRED AS TO OUR ALT AND WE RPTED LEAVING 'FL210 FOR FL200.' AT THAT TIME THE CENTER CTLR INFORMED US THAT WE SHOULD BE MAINTAINING FL220 AND GAVE US AN IMMEDIATE CLB AND TURN TO AVOID TFC AT FL210. UPON REACHING FL220 WE WERE THEN INFORMED WE MAY HAVE BUSTED AN ALT AND WERE GIVEN THE PHONE # OF THE DEN ARTCC. WE SUGGESTED THE CTLR REPLAY THE VOICE TAPE AND CHK OUR READBACK 'TO FL200.' THIS WAS DONE. THE WATCH SUPVR TOLD ME WE WERE CLRED TO MAINTAIN FL220, BUT READ BACK FL200 AND THE CTLR MISSED THE READBACK, SO THE MATTER WOULD BE HANDLED INTERNALLY AT THE CENTER AND HE DOUBTED WE WOULD HEAR ANYMORE ABOUT IT.
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.