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DH8 descent through occupied altitude had less than standard separation from another DH8. System error.
| Attributes | |
| ACN | 310278 |
| Time | |
| Date | 199506 |
| Day | Tue |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : phl |
| State Reference | PA |
| Altitude | msl bound lower : 5000 msl bound upper : 5000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : phl |
| Operator | common carrier : air carrier |
| Make Model Name | Dash 8 Series Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Route In Use | enroute : direct |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Dash 8 Series Undifferentiated or Other Model |
| 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 : approach |
| Qualification | controller : radar |
| Experience | controller military : 4 controller radar : 2 |
| ASRS Report | 310278 |
| 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 | atc equipment other atc equipment : unspecified other controllera |
| Resolutory Action | controller : issued new clearance |
| Consequence | faa : investigated |
| Miss Distance | horizontal : 5400 vertical : 300 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
I was working a satellite sector which also runs the final approach for our secondary runway. There were 2 DH8's both on the same heading, one at 6000 ft the other at 5000 ft. The higher aircraft was faster so the plan was to let him run by the lower then descend for the airport. I thought that I had given the lower aircraft a speed restr of 190 KTS which would have been just enough to do what I needed. My strip indicated that I did issue a speed restr, however, I later learned that I had issued the restr to another aircraft with a similar sounding call sign. This was a very busy session and most of the commuters were using similar call signs. Thinking that I would have enough room I descended the higher aircraft through the altitude of the lower. The conflict alert alarm sounded so I went back and issued diverging headings to both aircraft. In my haste to resolve this situation I created another by turning the lower aircraft to conflict with another (PA28). This situation was resolved with the DH8 making an immediate climb and a turn away from the PA28. Looking back I should have had a handoff man as a set of extra eyes. We also had just received a new conflict alert system that was alerting of everything that moved, so this proved to be a hinderance to me.
Original NASA ASRS Text
Title: DH8 DSCNT THROUGH OCCUPIED ALT HAD LTSS FROM ANOTHER DH8. SYS ERROR.
Narrative: I WAS WORKING A SATELLITE SECTOR WHICH ALSO RUNS THE FINAL APCH FOR OUR SECONDARY RWY. THERE WERE 2 DH8'S BOTH ON THE SAME HDG, ONE AT 6000 FT THE OTHER AT 5000 FT. THE HIGHER ACFT WAS FASTER SO THE PLAN WAS TO LET HIM RUN BY THE LOWER THEN DSND FOR THE ARPT. I THOUGHT THAT I HAD GIVEN THE LOWER ACFT A SPD RESTR OF 190 KTS WHICH WOULD HAVE BEEN JUST ENOUGH TO DO WHAT I NEEDED. MY STRIP INDICATED THAT I DID ISSUE A SPD RESTR, HOWEVER, I LATER LEARNED THAT I HAD ISSUED THE RESTR TO ANOTHER ACFT WITH A SIMILAR SOUNDING CALL SIGN. THIS WAS A VERY BUSY SESSION AND MOST OF THE COMMUTERS WERE USING SIMILAR CALL SIGNS. THINKING THAT I WOULD HAVE ENOUGH ROOM I DSNDED THE HIGHER ACFT THROUGH THE ALT OF THE LOWER. THE CONFLICT ALERT ALARM SOUNDED SO I WENT BACK AND ISSUED DIVERGING HDGS TO BOTH ACFT. IN MY HASTE TO RESOLVE THIS SIT I CREATED ANOTHER BY TURNING THE LOWER ACFT TO CONFLICT WITH ANOTHER (PA28). THIS SIT WAS RESOLVED WITH THE DH8 MAKING AN IMMEDIATE CLB AND A TURN AWAY FROM THE PA28. LOOKING BACK I SHOULD HAVE HAD A HDOF MAN AS A SET OF EXTRA EYES. WE ALSO HAD JUST RECEIVED A NEW CONFLICT ALERT SYS THAT WAS ALERTING OF EVERYTHING THAT MOVED, SO THIS PROVED TO BE A HINDERANCE TO ME.
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.