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Small aircraft Y had less than standard separation from air carrier X making visual approach. System error.
| Attributes | |
| ACN | 216139 |
| Time | |
| Date | 199207 |
| Day | Wed |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : psc |
| State Reference | WA |
| Altitude | msl bound lower : 3000 msl bound upper : 3000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | tracon : psc |
| Operator | common carrier : air carrier |
| Make Model Name | Small Transport, Low Wing, 2 Turboprop Eng |
| Flight Phase | descent : approach descent other |
| Flight Plan | IFR |
| Aircraft 2 | |
| Operator | general aviation : personal |
| Make Model Name | Small Aircraft, Low Wing, 1 Eng, Retractable Gear |
| Flight Phase | descent : approach |
| Route In Use | approach : straight in |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | government : faa |
| Function | controller : approach |
| Qualification | controller : radar |
| Experience | controller military : 10 controller non radar : 5 controller radar : 3 |
| ASRS Report | 216139 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | conflict : airborne less severe non adherence : required legal separation non adherence : published procedure |
| Independent Detector | other controllera |
| Resolutory Action | controller : issued new clearance other |
| Consequence | Other |
| Miss Distance | horizontal : 9000 vertical : 0 |
| Supplementary | |
| Primary Problem | ATC Human Performance |
| Air Traffic Incident | Operational Error |
Narrative:
The problem began when air carrier X was cleared for a visual approach approximately 15 mi west and instructed to 'contact tower crossing the river' which was about 10 west of the airport. Small aircraft Y was on an IFR flight plan also inbound but from the northwest on a converging course with air carrier X. Small aircraft Y was descending to 3000, still inbound on an airway which put him almost straight-in to the arrival runway. The pilot of small aircraft Y vividly expressed his appreciation for being assigned the straight-in runway. When I saw that small aircraft Y, who was approximately equidistant from the runway with air carrier X, was not reducing as I had expected, I saw that I would need to vector small aircraft Y off of his straight-in for sequence. I assigned the vector and the pilot questioned it. I then assigned another vector and told the pilot to turn now. By this time, air carrier X was certainly not going to miss small aircraft Y by 3 mi, but air carrier X was still 1500 ft above small aircraft Y. I assigned air carrier X an altitude 1000 ft above small aircraft Y, but air carrier X did not respond (he had contacted tower while crossing the river). If I would have done one of 2 things, the loss of separation would not have occurred. 1) not clear and switch air carrier X until the potential conflict was resolved. 2) reduce or vector small aircraft Y earlier.
Original NASA ASRS Text
Title: SMA Y HAD LTSS FROM ACR X MAKING VISUAL APCH. SYS ERROR.
Narrative: THE PROBLEM BEGAN WHEN ACR X WAS CLRED FOR A VISUAL APCH APPROX 15 MI W AND INSTRUCTED TO 'CONTACT TWR XING THE RIVER' WHICH WAS ABOUT 10 W OF THE ARPT. SMA Y WAS ON AN IFR FLT PLAN ALSO INBOUND BUT FROM THE NW ON A CONVERGING COURSE WITH ACR X. SMA Y WAS DSNDING TO 3000, STILL INBOUND ON AN AIRWAY WHICH PUT HIM ALMOST STRAIGHT-IN TO THE ARR RWY. THE PLT OF SMA Y VIVIDLY EXPRESSED HIS APPRECIATION FOR BEING ASSIGNED THE STRAIGHT-IN RWY. WHEN I SAW THAT SMA Y, WHO WAS APPROX EQUIDISTANT FROM THE RWY WITH ACR X, WAS NOT REDUCING AS I HAD EXPECTED, I SAW THAT I WOULD NEED TO VECTOR SMA Y OFF OF HIS STRAIGHT-IN FOR SEQUENCE. I ASSIGNED THE VECTOR AND THE PLT QUESTIONED IT. I THEN ASSIGNED ANOTHER VECTOR AND TOLD THE PLT TO TURN NOW. BY THIS TIME, ACR X WAS CERTAINLY NOT GOING TO MISS SMA Y BY 3 MI, BUT ACR X WAS STILL 1500 FT ABOVE SMA Y. I ASSIGNED ACR X AN ALT 1000 FT ABOVE SMA Y, BUT ACR X DID NOT RESPOND (HE HAD CONTACTED TWR WHILE XING THE RIVER). IF I WOULD HAVE DONE ONE OF 2 THINGS, THE LOSS OF SEPARATION WOULD NOT HAVE OCCURRED. 1) NOT CLR AND SWITCH ACR X UNTIL THE POTENTIAL CONFLICT WAS RESOLVED. 2) REDUCE OR VECTOR SMA Y EARLIER.
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.