Narrative:

Flight was being vectored by geg approach for ILS runway 3 approach to geg international, and had been told by ATC to expect to hold. Captain requested first officer to check latest WX reports and forecast for alternate airport. First officer was complying using #1 radio, but was monitoring both radios (company and ATC). Aircraft was level at 10000' MSL when approach control issued the clearance to 'turn left heading 030 degree, descend and maintain 5000''. Captain acknowledged clearance, reset altitude alerter to 5000' and began descent and turn. Evidently approach control did not hear the acknowledgement and queried flight if it had copied clearance as previously stated above. Captain restated his acknowledgement that we had received clearance to 'turn left heading 030 degree and descend to 5000''. Approach controller stated 'roger'. As flight was descending through 8400', approach controller issued clearance to 'turn right immediately heading 070 degree'. The captain immediately complied with turn, and the first officer (who had resumed responsibility for radio communications with ATC) acknowledged clearance. Approach controller than stated we had been cleared to maintain 9000'. As the captain had acknowledged previous clearance to 5000', he replied to the controller 'negative, we were clrd to 5000', after which the controller replied 'negative, 9000'. Captain immediately initiated climb to 9000' (to resolve traffic conflict as priority in situation rather than argue), and told approach controller to 'pull the tapes' for reference. Captain contacted ATC approach control supervisor on the ground. After reviewing the tape, he indicated we had indeed been cleared to the heading of 030 degree and 5000', and had indeed acknowledged this clearance twice. He also indicated, however, that 35 seconds later the controller had issued a single phrase clearance to us to maintain 9000'. Neither the captain nor the first officer heard or acknowledged this clearance. Both pilots were monitoring ATC below 10000'. The tapes confirmed neither pilot had acknowledged clearance, and it was not restated. The control supervisor indicated there had been a traffic conflict, but that our clearance was to 5000' since we had not acknowledged clearance to maintain 9000', and such a clearance is not valid west/O acknowledgement. The reporter feels that a contributing factor to the incident was controller saturation. The conditions at geg were very marginal, there were up to 12 (approximately) aircraft being vectored for the approach, and 2 aircraft had missed the approach. Frequency congestion may have been an element in the crew not hearing the single, subsequent clearance to maintain 9000'.

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Original NASA ASRS Text

Title: COMMUTER ARRIVING GEG MISTAKENLY CLEARED TO 5000', LOSS OF SEPARTION RESULTS.

Narrative: FLT WAS BEING VECTORED BY GEG APCH FOR ILS RWY 3 APCH TO GEG INTL, AND HAD BEEN TOLD BY ATC TO EXPECT TO HOLD. CAPT REQUESTED F/O TO CHK LATEST WX RPTS AND FORECAST FOR ALTERNATE ARPT. F/O WAS COMPLYING USING #1 RADIO, BUT WAS MONITORING BOTH RADIOS (COMPANY AND ATC). ACFT WAS LEVEL AT 10000' MSL WHEN APCH CTL ISSUED THE CLRNC TO 'TURN LEFT HDG 030 DEG, DSND AND MAINTAIN 5000''. CAPT ACKNOWLEDGED CLRNC, RESET ALT ALERTER TO 5000' AND BEGAN DSCNT AND TURN. EVIDENTLY APCH CTL DID NOT HEAR THE ACKNOWLEDGEMENT AND QUERIED FLT IF IT HAD COPIED CLRNC AS PREVIOUSLY STATED ABOVE. CAPT RESTATED HIS ACKNOWLEDGEMENT THAT WE HAD RECEIVED CLRNC TO 'TURN L HDG 030 DEG AND DSND TO 5000''. APCH CTLR STATED 'ROGER'. AS FLT WAS DSNDING THROUGH 8400', APCH CTLR ISSUED CLRNC TO 'TURN R IMMEDIATELY HDG 070 DEG'. THE CAPT IMMEDIATELY COMPLIED WITH TURN, AND THE F/O (WHO HAD RESUMED RESPONSIBILITY FOR RADIO COMS WITH ATC) ACKNOWLEDGED CLRNC. APCH CTLR THAN STATED WE HAD BEEN CLRED TO MAINTAIN 9000'. AS THE CAPT HAD ACKNOWLEDGED PREVIOUS CLRNC TO 5000', HE REPLIED TO THE CTLR 'NEGATIVE, WE WERE CLRD TO 5000', AFTER WHICH THE CTLR REPLIED 'NEGATIVE, 9000'. CAPT IMMEDIATELY INITIATED CLB TO 9000' (TO RESOLVE TFC CONFLICT AS PRIORITY IN SITUATION RATHER THAN ARGUE), AND TOLD APCH CTLR TO 'PULL THE TAPES' FOR REFERENCE. CAPT CONTACTED ATC APCH CTL SUPVR ON THE GND. AFTER REVIEWING THE TAPE, HE INDICATED WE HAD INDEED BEEN CLRED TO THE HDG OF 030 DEG AND 5000', AND HAD INDEED ACKNOWLEDGED THIS CLRNC TWICE. HE ALSO INDICATED, HOWEVER, THAT 35 SECS LATER THE CTLR HAD ISSUED A SINGLE PHRASE CLRNC TO US TO MAINTAIN 9000'. NEITHER THE CAPT NOR THE F/O HEARD OR ACKNOWLEDGED THIS CLRNC. BOTH PLTS WERE MONITORING ATC BELOW 10000'. THE TAPES CONFIRMED NEITHER PLT HAD ACKNOWLEDGED CLRNC, AND IT WAS NOT RESTATED. THE CTL SUPVR INDICATED THERE HAD BEEN A TFC CONFLICT, BUT THAT OUR CLRNC WAS TO 5000' SINCE WE HAD NOT ACKNOWLEDGED CLRNC TO MAINTAIN 9000', AND SUCH A CLRNC IS NOT VALID W/O ACKNOWLEDGEMENT. THE RPTR FEELS THAT A CONTRIBUTING FACTOR TO THE INCIDENT WAS CTLR SATURATION. THE CONDITIONS AT GEG WERE VERY MARGINAL, THERE WERE UP TO 12 (APPROX) ACFT BEING VECTORED FOR THE APCH, AND 2 ACFT HAD MISSED THE APCH. FREQ CONGESTION MAY HAVE BEEN AN ELEMENT IN THE CREW NOT HEARING THE SINGLE, SUBSEQUENT CLRNC TO MAINTAIN 9000'.

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.