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ARTCC radar controller does not challenge weak readback, and observes a C525 descend, when the clearance was intended for another aircraft. Actions taken were insufficient to maintain separation.
| Attributes | |
| ACN | 411742 |
| Time | |
| Date | 199808 |
| Day | Thu |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : syr |
| State Reference | NY |
| Altitude | msl bound lower : 26000 msl bound upper : 26000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zbw tower : bda |
| Operator | general aviation : personal |
| Make Model Name | Cessna Citation Undifferentiated or Other Model |
| Operating Under FAR Part | Part 91 |
| Navigation In Use | Other |
| Flight Phase | cruise other descent other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller radar : 3 |
| ASRS Report | 411742 |
| Person 2 | |
| Affiliation | Other |
| Function | flight crew : single pilot |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : clearance non adherence : published procedure non adherence : required legal separation |
| Independent Detector | atc equipment other atc equipment : unspecified other controllera |
| Resolutory Action | controller : issued new clearance flight crew : took evasive action other |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 24600 vertical : 200 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
A C525 (X) came over descending to FL270. A B737 (Y) was climbing to FL250. Both aircraft were in level flight at FL270 and FL250 respectively. I then issued a climb to FL260 to the B737. Then I called traffic to both aircraft. The C525 replied he had traffic in sight. I then told the C525 I had some amended routing when he was ready to copy. It was taking him a while to respond and I was busy, so I went to my next move which was to clear aircraft air carrier (Z) to descend to FL200. The C525 read back his descent clearance. The readback was weak and garbled and he responded with a partial call sign. I did not catch this readback. A few moments later, I noticed the C525 start what appeared to be a descent. I questioned him as to his assigned altitude. When I realized he was descending, I took corrective action to re-establish separation. I feel there were a few reasons for this error, I did not catch the bad readback, and the C525 had a bad radio and did not use his full call sign for the readback. The other air carrier was also not paying attention and missed his clearance. Also the other air carrier missed the fact that another aircraft took his clearance, the radar computer, cdc, blinked, causing a distraction and increased workload.
Original NASA ASRS Text
Title: ARTCC RADAR CTLR DOES NOT CHALLENGE WEAK READBACK, AND OBSERVES A C525 DSND, WHEN THE CLRNC WAS INTENDED FOR ANOTHER ACFT. ACTIONS TAKEN WERE INSUFFICIENT TO MAINTAIN SEPARATION.
Narrative: A C525 (X) CAME OVER DSNDING TO FL270. A B737 (Y) WAS CLBING TO FL250. BOTH ACFT WERE IN LEVEL FLT AT FL270 AND FL250 RESPECTIVELY. I THEN ISSUED A CLB TO FL260 TO THE B737. THEN I CALLED TFC TO BOTH ACFT. THE C525 REPLIED HE HAD TFC IN SIGHT. I THEN TOLD THE C525 I HAD SOME AMENDED ROUTING WHEN HE WAS READY TO COPY. IT WAS TAKING HIM A WHILE TO RESPOND AND I WAS BUSY, SO I WENT TO MY NEXT MOVE WHICH WAS TO CLR ACFT ACR (Z) TO DSND TO FL200. THE C525 READ BACK HIS DSCNT CLRNC. THE READBACK WAS WEAK AND GARBLED AND HE RESPONDED WITH A PARTIAL CALL SIGN. I DID NOT CATCH THIS READBACK. A FEW MOMENTS LATER, I NOTICED THE C525 START WHAT APPEARED TO BE A DSCNT. I QUESTIONED HIM AS TO HIS ASSIGNED ALT. WHEN I REALIZED HE WAS DSNDING, I TOOK CORRECTIVE ACTION TO RE-ESTABLISH SEPARATION. I FEEL THERE WERE A FEW REASONS FOR THIS ERROR, I DID NOT CATCH THE BAD READBACK, AND THE C525 HAD A BAD RADIO AND DID NOT USE HIS FULL CALL SIGN FOR THE READBACK. THE OTHER ACR WAS ALSO NOT PAYING ATTN AND MISSED HIS CLRNC. ALSO THE OTHER ACR MISSED THE FACT THAT ANOTHER ACFT TOOK HIS CLRNC, THE RADAR COMPUTER, CDC, BLINKED, CAUSING A DISTR AND INCREASED WORKLOAD.
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.