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Loss of separation when an air carrier MD88 descends below new assigned altitude of FL250 and conflicts with an air carrier carj at FL240. Flight crew had a previous crossing restr at FL240. Reporter missed a portion of the FL240 clearance readback when the flight crew repeated the altitude of crossing restr.
| Attributes | |
| ACN | 392622 |
| Time | |
| Date | 199801 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : ecg |
| State Reference | KY |
| Altitude | msl bound lower : 24000 msl bound upper : 24000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zid |
| Operator | common carrier : air carrier |
| Make Model Name | MD-88 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Challenger CL604 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | climbout : intermediate altitude cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller radar : 6 |
| ASRS Report | 392622 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : required legal separation non adherence : published procedure non adherence : clearance |
| Independent Detector | other controllera |
| Resolutory Action | none taken : detected after the fact |
| Consequence | Other |
| Miss Distance | horizontal : 6000 vertical : 200 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Pilot Deviation Operational Error |
Narrative:
Cleared MD88 direct sweed, cross 20 mi east sweed at FL240. Carj climbing off cvg, I stopped carj at FL240, then stopped MD88 at FL250. Later, I asked MD88 to confirm FL250. Response was affirmative and making the previous crossing at FL240. I missed him saying FL240. I later called traffic, MD88 called it in sight and descended into carj.
Original NASA ASRS Text
Title: LOSS OF SEPARATION WHEN AN ACR MD88 DSNDS BELOW NEW ASSIGNED ALT OF FL250 AND CONFLICTS WITH AN ACR CARJ AT FL240. FLC HAD A PREVIOUS XING RESTR AT FL240. RPTR MISSED A PORTION OF THE FL240 CLRNC READBACK WHEN THE FLC REPEATED THE ALT OF XING RESTR.
Narrative: CLRED MD88 DIRECT SWEED, CROSS 20 MI E SWEED AT FL240. CARJ CLBING OFF CVG, I STOPPED CARJ AT FL240, THEN STOPPED MD88 AT FL250. LATER, I ASKED MD88 TO CONFIRM FL250. RESPONSE WAS AFFIRMATIVE AND MAKING THE PREVIOUS XING AT FL240. I MISSED HIM SAYING FL240. I LATER CALLED TFC, MD88 CALLED IT IN SIGHT AND DSNDED INTO CARJ.
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.