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Air carrier Y was descended through air carrier X altitude while on an instrument approach. Less than standard separation occurred. System error.
| Attributes | |
| ACN | 112346 |
| Time | |
| Date | 198905 |
| Day | Thu |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : pit |
| State Reference | PA |
| Altitude | msl bound lower : 4400 msl bound upper : 4400 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : pit tracon : snb |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Flight Phase | cruise other descent : approach |
| Route In Use | arrival other enroute : on vectors |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | common carrier : air carrier |
| Make Model Name | Medium Large Transport, Low Wing, 2 Turbojet Eng |
| Navigation In Use | Other |
| Flight Phase | descent : approach descent other |
| Route In Use | approach : straight in arrival other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| ASRS Report | 112346 |
| Person 2 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : developmental |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation non adherence : published procedure other anomaly other |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance none taken : insufficient time other |
| Miss Distance | horizontal : 5500 vertical : 500 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
While training a radar developmental controller this incident occurred. The trainee was late on a left base leg turn with air carrier X reference to a straight-in air carrier Y that was to follow. Instructions given by the developmental did not insure vertical separation. I took the frequency in order to separate the 2 aircraft. The base leg aircraft was advised to level off while the straight-in air carrier Y was advised to expedite descent to 3000' immediately. The target's paths came less than 1 mi of each other and the last made C of each aircraft indicated 500' vertical separation. The straight in air carrier Y he had while being turned and descended advised he had the base leg air carrier X in sight and was told to maintain visual separation.
Original NASA ASRS Text
Title: ACR Y WAS DESCENDED THROUGH ACR X ALT WHILE ON AN INSTRUMENT APCH. LESS THAN STANDARD SEPARATION OCCURRED. SYSTEM ERROR.
Narrative: WHILE TRAINING A RADAR DEVELOPMENTAL CTLR THIS INCIDENT OCCURRED. THE TRAINEE WAS LATE ON A LEFT BASE LEG TURN WITH ACR X REFERENCE TO A STRAIGHT-IN ACR Y THAT WAS TO FOLLOW. INSTRUCTIONS GIVEN BY THE DEVELOPMENTAL DID NOT INSURE VERTICAL SEPARATION. I TOOK THE FREQ IN ORDER TO SEPARATE THE 2 ACFT. THE BASE LEG ACFT WAS ADVISED TO LEVEL OFF WHILE THE STRAIGHT-IN ACR Y WAS ADVISED TO EXPEDITE DSCNT TO 3000' IMMEDIATELY. THE TARGET'S PATHS CAME LESS THAN 1 MI OF EACH OTHER AND THE LAST MADE C OF EACH ACFT INDICATED 500' VERTICAL SEPARATION. THE STRAIGHT IN ACR Y HE HAD WHILE BEING TURNED AND DESCENDED ADVISED HE HAD THE BASE LEG ACR X IN SIGHT AND WAS TOLD TO MAINTAIN VISUAL SEPARATION.
Data retrieved from NASA's ASRS site as of August 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.