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ZOB controller described operational error at FL306 when incorrect altitude read back was missed and separation was lost.
| Attributes | |
| ACN | 776621 |
| Time | |
| Date | 200802 |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | navaid : ape.vortac |
| State Reference | OH |
| Altitude | msl single value : 30600 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob.artcc |
| Operator | general aviation : personal |
| Make Model Name | Falcon 50 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | descent : vacating altitude |
| Flight Plan | IFR |
| Aircraft 2 | |
| Controlling Facilities | artcc : zob.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | MD-88 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller radar : 16 controller time certified in position1 : 6 flight time total : 106 |
| ASRS Report | 776621 |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation |
| Independent Detector | atc equipment : conflict alert other controllera |
| Resolutory Action | controller : issued new clearance controller : issued alert |
| Consequence | faa : investigated |
| Supplementary | |
| Problem Areas | ATC Human Performance |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
Aircraft X was issued a clearance to cross 25 mi north of ape at FL320. Aircraft X questioned the clearance to cross 25 mi north of ape at FL250. I was concerned as to the accuracy of my DME and after measuring; responded 'affirmative.' I then restated the clearance to cross 25 mi north of ape at FL320. Aircraft X read back a clearance to cross 25 mi north of ape at FL250. I switched aircraft X to ZID when the aircraft was out of FL340 (approximately). Aircraft X checked on with ZID out of FL315 for FL250. The ZID controller immediately amended the altitude and cleared aircraft X to maintain FL310. Aircraft X descended to FL306 before returning to FL310; air carrier Y was inbound to dtw at FL300.
Original NASA ASRS Text
Title: ZOB CTLR DESCRIBED OPERROR AT FL306 WHEN INCORRECT ALT READ BACK WAS MISSED AND SEPARATION WAS LOST.
Narrative: ACFT X WAS ISSUED A CLRNC TO CROSS 25 MI N OF APE AT FL320. ACFT X QUESTIONED THE CLRNC TO CROSS 25 MI N OF APE AT FL250. I WAS CONCERNED AS TO THE ACCURACY OF MY DME AND AFTER MEASURING; RESPONDED 'AFFIRMATIVE.' I THEN RESTATED THE CLRNC TO CROSS 25 MI N OF APE AT FL320. ACFT X READ BACK A CLRNC TO CROSS 25 MI N OF APE AT FL250. I SWITCHED ACFT X TO ZID WHEN THE ACFT WAS OUT OF FL340 (APPROX). ACFT X CHKED ON WITH ZID OUT OF FL315 FOR FL250. THE ZID CTLR IMMEDIATELY AMENDED THE ALT AND CLRED ACFT X TO MAINTAIN FL310. ACFT X DSNDED TO FL306 BEFORE RETURNING TO FL310; ACR Y WAS INBOUND TO DTW AT FL300.
Data retrieved from NASA's ASRS site as of May 2009 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.