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ARTCC deviating controller issued wrong altitude to an aircraft under his control which resulted in less than standard separation between two aircraft on converging courses.
| Attributes | |
| ACN | 143834 |
| Time | |
| Date | 199004 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : atr |
| State Reference | DE |
| Altitude | msl bound lower : 8000 msl bound upper : 8700 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdc |
| Operator | common carrier : air carrier |
| Make Model Name | Widebody, Low Wing, 4 Turbojet Eng |
| Navigation In Use | Other |
| Flight Phase | descent other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | general aviation : personal |
| Make Model Name | Small Aircraft, Low Wing, 1 Eng, Retractable Gear |
| Flight Phase | cruise other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : developmental |
| Experience | controller non radar : 1 |
| ASRS Report | 143834 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance other |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 16800 vertical : 700 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
An widebody transport X was level at 10000' direct dover AFB. An small aircraft Y was level at 8000' swbnd. I inadvertently cleared widebody transport X to 8000', thinking I had cleared him to 9000'. 9000' was placed in the datablock via an interim altitude message. I called traffic to small aircraft Y as, '9 O'clock 3 mi nwbnd, descending to niner thousand feet'. My instrument took the frequency when he saw widebody transport X's mode C at 8700' descending. My instrument ask widebody transport X to verify level at niner thousand feet. The pilot of widebody transport X replied that he had a descent to 8000'. After reviewing the tapes, it showed that I had issued 8000' to widebody transport X. I issued a wrong altitude clearance and I did not catch the readback. After reviewing the ntap, it showed the targets in a tail-to-tail situation when vertical sep was lost (2.8 lateral and increasing).
Original NASA ASRS Text
Title: ARTCC DEVIATING CTLR ISSUED WRONG ALT TO AN ACFT UNDER HIS CTL WHICH RESULTED IN LESS THAN STANDARD SEPARATION BETWEEN TWO ACFT ON CONVERGING COURSES.
Narrative: AN WDB X WAS LEVEL AT 10000' DIRECT DOVER AFB. AN SMA Y WAS LEVEL AT 8000' SWBND. I INADVERTENTLY CLRED WDB X TO 8000', THINKING I HAD CLRED HIM TO 9000'. 9000' WAS PLACED IN THE DATABLOCK VIA AN INTERIM ALT MESSAGE. I CALLED TFC TO SMA Y AS, '9 O'CLOCK 3 MI NWBND, DSNDING TO NINER THOUSAND FEET'. MY INSTR TOOK THE FREQ WHEN HE SAW WDB X'S MODE C AT 8700' DSNDING. MY INSTR ASK WDB X TO VERIFY LEVEL AT NINER THOUSAND FEET. THE PLT OF WDB X REPLIED THAT HE HAD A DSNT TO 8000'. AFTER REVIEWING THE TAPES, IT SHOWED THAT I HAD ISSUED 8000' TO WDB X. I ISSUED A WRONG ALT CLRNC AND I DID NOT CATCH THE READBACK. AFTER REVIEWING THE NTAP, IT SHOWED THE TARGETS IN A TAIL-TO-TAIL SITUATION WHEN VERT SEP WAS LOST (2.8 LATERAL AND INCREASING).
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.