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Mlt misinterp clearance and descended causing less than standard separation with an large transport. Controller missed in correct readback.
| Attributes | |
| ACN | 197299 |
| Time | |
| Date | 199112 |
| Day | Sat |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : tth |
| State Reference | IN |
| Altitude | msl bound lower : 33000 msl bound upper : 34200 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zid |
| Operator | other |
| Make Model Name | Military Transport |
| Flight Phase | climbout : intermediate altitude cruise other descent other |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Large Transport, Low Wing, 3 Turbojet Eng |
| Flight Phase | cruise other descent other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller radar : 1 |
| ASRS Report | 197299 |
| Person 2 | |
| Affiliation | government : military |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : military |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation non adherence : clearance |
| Independent Detector | atc equipment other atc equipment : unspecified other controllera |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Miss Distance | horizontal : 25200 vertical : 1200 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error Pilot Deviation |
Narrative:
Mlt X called on frequency descending to FL350, controller turned mlt X 20 degree right told to maintain FL350 and advised mlt X when clear of traffic (large transport X), controller would need a good rate through FL310. Mlt X replied that he was leaving FL350 for FL310 in a right turn. Controller missed the readback and separation was lost. Conflict alert did not activate until departure activated! Mlt X was climbed up to FL350. Large transport Y was descended to FL310. Sector did not have a non radar controller plugged in because staffing was very low. Staffing is very low at our whole center. If there was a non radar controller plugged in, they might have caught the missed readback.
Original NASA ASRS Text
Title: MLT MISINTERP CLRNC AND DSNDED CAUSING LTSS WITH AN LGT. CTLR MISSED IN CORRECT READBACK.
Narrative: MLT X CALLED ON FREQ DSNDING TO FL350, CTLR TURNED MLT X 20 DEG R TOLD TO MAINTAIN FL350 AND ADVISED MLT X WHEN CLR OF TFC (LGT X), CTLR WOULD NEED A GOOD RATE THROUGH FL310. MLT X REPLIED THAT HE WAS LEAVING FL350 FOR FL310 IN A R TURN. CTLR MISSED THE READBACK AND SEPARATION WAS LOST. CONFLICT ALERT DID NOT ACTIVATE UNTIL DEP ACTIVATED! MLT X WAS CLBED UP TO FL350. LGT Y WAS DSNDED TO FL310. SECTOR DID NOT HAVE A NON RADAR CTLR PLUGGED IN BECAUSE STAFFING WAS VERY LOW. STAFFING IS VERY LOW AT OUR WHOLE CENTER. IF THERE WAS A NON RADAR CTLR PLUGGED IN, THEY MIGHT HAVE CAUGHT THE MISSED READBACK.
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.