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Aircraft Y descent to occupied altitude. Had less than standard separation from aircraft X. System error.
| Attributes | |
| ACN | 263807 |
| Time | |
| Date | 199401 |
| Day | Fri |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : cho |
| State Reference | VA |
| Altitude | msl bound lower : 29000 msl bound upper : 29000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zdc tower : pvd |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Commercial Fixed Wing |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : radar |
| Qualification | controller : radar |
| Experience | controller radar : 19 |
| ASRS Report | 263807 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : published procedure non adherence : required legal separation |
| Independent Detector | other controllera |
| Resolutory Action | none taken : detected after the fact |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 21360 vertical : 0 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
The plan to descend aircraft X at FL290 eastbound to FL280 and then to descend aircraft Y at FL310 to FL290. The mistake that led to loss of separation was to put the interim altitude of FL280 in the data block of aircraft X which was not on the frequency. After issuing 2 clrncs to aircraft X with no acknowledgements, then looking back at FL280 in the data block and thinking one thing and not seeing the actual altitude in the true data block of FL290. The mistake of mistaking FL280 in the interim data block.
Original NASA ASRS Text
Title: ACFT Y DSCNT TO OCCUPIED ALT. HAD LTSS FROM ACFT X. SYS ERROR.
Narrative: THE PLAN TO DSND ACFT X AT FL290 EBOUND TO FL280 AND THEN TO DSND ACFT Y AT FL310 TO FL290. THE MISTAKE THAT LED TO LOSS OF SEPARATION WAS TO PUT THE INTERIM ALT OF FL280 IN THE DATA BLOCK OF ACFT X WHICH WAS NOT ON THE FREQ. AFTER ISSUING 2 CLRNCS TO ACFT X WITH NO ACKNOWLEDGEMENTS, THEN LOOKING BACK AT FL280 IN THE DATA BLOCK AND THINKING ONE THING AND NOT SEEING THE ACTUAL ALT IN THE TRUE DATA BLOCK OF FL290. THE MISTAKE OF MISTAKING FL280 IN THE INTERIM DATA BLOCK.
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.