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ZOB radar controller experienced loss of separation when missing incorrect and wrong aircraft clearance readbacks.
| Attributes | |
| ACN | 580680 |
| Time | |
| Date | 200304 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| State Reference | NY |
| Altitude | msl single value : 31000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | A320 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | descent : intermediate altitude |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zob.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | descent : intermediate altitude |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar pilot : instrument |
| Experience | controller limited radar : 17 controller radar : 15 controller time certified in position1 : 15 flight time total : 3000 |
| ASRS Report | 580680 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : clearance non adherence : published procedure non adherence : required legal separation |
| Independent Detector | atc equipment : conflict alert other controllera |
| Resolutory Action | none taken : insufficient time |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 15000 vertical : 700 |
| Supplementary | |
| Problem Areas | ATC Human Performance Flight Crew Human Performance |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Aircraft X inbound to yyz was at FL350. I initially issued aircraft X a clearance to FL330. I then issued a clearance to aircraft Z to descend to FL280. Aircraft X read back, 'aircraft X leaving FL330 for FL280.' I did not hear the call sign for aircraft X. Aircraft Y was swbound at FL310 descending to FL280. I noticed that aircraft X had descended below FL330 (his original clearance). I asked aircraft X 'aircraft X verify your altitude at FL310!' he read back 'roger, aircraft X is through FL314 for FL280.' I again never heard the last part of his readback. I expedited aircraft Y through FL290 and finally stopped aircraft X at FL292. I made 2 listening errors in the matter of 70 seconds and separation was lost.
Original NASA ASRS Text
Title: ZOB RADAR CTLR EXPERIENCED LOSS OF SEPARATION WHEN MISSING INCORRECT AND WRONG ACFT CLRNC READBACKS.
Narrative: ACFT X INBOUND TO YYZ WAS AT FL350. I INITIALLY ISSUED ACFT X A CLRNC TO FL330. I THEN ISSUED A CLRNC TO ACFT Z TO DSND TO FL280. ACFT X READ BACK, 'ACFT X LEAVING FL330 FOR FL280.' I DID NOT HEAR THE CALL SIGN FOR ACFT X. ACFT Y WAS SWBOUND AT FL310 DSNDING TO FL280. I NOTICED THAT ACFT X HAD DSNDED BELOW FL330 (HIS ORIGINAL CLRNC). I ASKED ACFT X 'ACFT X VERIFY YOUR ALT AT FL310!' HE READ BACK 'ROGER, ACFT X IS THROUGH FL314 FOR FL280.' I AGAIN NEVER HEARD THE LAST PART OF HIS READBACK. I EXPEDITED ACFT Y THROUGH FL290 AND FINALLY STOPPED ACFT X AT FL292. I MADE 2 LISTENING ERRORS IN THE MATTER OF 70 SECONDS AND SEPARATION WAS LOST.
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.