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ZDC issues descent clearance, thinking he has issued an altitude that provides separation, even though the pilot correctly read back the conflicting altitude.
| Attributes | |
| ACN | 517768 |
| Time | |
| Date | 200107 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | navaid : fak.vortac |
| State Reference | VA |
| Altitude | msl single value : 21000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdc.artcc tracon : n90.tracon |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other vortac |
| Flight Phase | descent : intermediate altitude |
| Route In Use | arrival star : ns |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zdc.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 2 Turbojet Eng |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other other vortac |
| Flight Phase | cruise : level |
| Route In Use | arrival star : coatt.coatt4 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar controller : handoff position |
| Qualification | controller : radar |
| Experience | controller radar : 13 controller time certified in position1 : 12 |
| ASRS Report | 517768 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : instrument pilot : multi engine pilot : private pilot : atp pilot : cfi pilot : commercial pilot : flight engineer |
| Experience | flight time last 90 days : 250 flight time total : 12000 flight time type : 800 |
| ASRS Report | 517766 |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : published procedure non adherence : required legal separation |
| Independent Detector | atc equipment : conflict alert other controllera other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : took precautionary avoidance action |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 12000 vertical : 200 |
| Supplementary | |
| Problem Areas | ATC Human Performance Flight Crew Human Performance |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Air carrier X was given a descent to FL220 and then traffic was called at 2 O'clock and 4 mi nebound, an air carrier Y, at FL210. Air carrier X responded roger and descended through FL220 going to FL200. Loss of center separation and when air carrier X was questioned about descent clearance, he responded by saying he was cleared to FL200. Upon reviewing voice tapes, air carrier X was cleared to FL200 and I missed the readback. I am not sure why I gave air carrier FL200 because I do not own FL200. Traffic was not really heavy, but I had just finished lining up 10 arrs into dca and air carrier X was the last one. I do question why air carrier X didn't ask me to restate his altitude clearance after I gave him his traffic call. Supplemental information from acn 517766: air carrier X flight XXX passed through our altitude of FL210 on his way to FL200, resulting in an RA and vector from ATC to 090 degrees off the coatt 4 arrival. We complied with the RA. Flight landed uneventful.
Original NASA ASRS Text
Title: ZDC ISSUES DSCNT CLRNC, THINKING HE HAS ISSUED AN ALT THAT PROVIDES SEPARATION, EVEN THOUGH THE PLT CORRECTLY READ BACK THE CONFLICTING ALT.
Narrative: ACR X WAS GIVEN A DSCNT TO FL220 AND THEN TFC WAS CALLED AT 2 O'CLOCK AND 4 MI NEBOUND, AN ACR Y, AT FL210. ACR X RESPONDED ROGER AND DSNDED THROUGH FL220 GOING TO FL200. LOSS OF CTR SEPARATION AND WHEN ACR X WAS QUESTIONED ABOUT DSCNT CLRNC, HE RESPONDED BY SAYING HE WAS CLRED TO FL200. UPON REVIEWING VOICE TAPES, ACR X WAS CLRED TO FL200 AND I MISSED THE READBACK. I AM NOT SURE WHY I GAVE ACR FL200 BECAUSE I DO NOT OWN FL200. TFC WAS NOT REALLY HVY, BUT I HAD JUST FINISHED LINING UP 10 ARRS INTO DCA AND ACR X WAS THE LAST ONE. I DO QUESTION WHY ACR X DIDN'T ASK ME TO RESTATE HIS ALT CLRNC AFTER I GAVE HIM HIS TFC CALL. SUPPLEMENTAL INFO FROM ACN 517766: ACR X FLT XXX PASSED THROUGH OUR ALT OF FL210 ON HIS WAY TO FL200, RESULTING IN AN RA AND VECTOR FROM ATC TO 090 DEGS OFF THE COATT 4 ARR. WE COMPLIED WITH THE RA. FLT LANDED UNEVENTFUL.
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.