Narrative:

Atx X tracking inbound on dak 220 radial to the VOR to expect approach to fyv airport, descending to 6000 MSL. Atx Y climbing out of fyv airport, swbnd to 5000 MSL. Trainee on position, working traffic. About 2 mins after departure, trainee asks atx X for position from dak. The reply is the 220 radial at 16 DME. Trainee then asks MTR 814 his position from dak to establish tail-to-tail separation of opposite direction traffic. Atx Y replies 193 radial at 20 DME. Trainee assumed the position report from atx Y was correct and proceeded to climb atx Y to 9000 MSL. Instructor immediately issued instruction to the atx Y to maintain 5000 MSL, whereupon the pilot of atx Y replied he had opposite direction traffic straight ahead (atx X). The primary error here was the erroneous report from atx Y. The rzc VORTAC is located 15 DME north of the fyv airport and is used as the primary approach fix for the fyv airspace. Dak VOR is a terminal VOR located 2.2 DME northwest of fyv airport. Aircraft cleared from fyv to join V63 off rzc, swbnd, often navigate off rzc after departure from fyv. Inbound traffic to fyv from the southwest usually navigate from the dak VOR. Often pilots in the southwest quadrant of the airspace are confused or forget which NAVAID they are navigating from. In this case, atx Y, swbnd to join V63, was navigating from rzc, and when he was requested to report his position, he replied the 193 radial at 20 DME -- this position was off rzc, not dak. Trainee did not realize the implausibility of a turboprop covering 20 mi in 2 mins, assumed the position report was correct, and proceeded to climb the aircraft in front of the inbound atx X aircraft. This happens quite frequently in our airspace, and owing to its lack of radar, the controller at fyv must rely on common sense to ascertain whether or not a pilot report is indeed accurate, or if the report appears to be way off base. In this case, the instructor's experience came into play to avert a potential midair collision, once he recognized the impossibility of atx Y's position report. Not only must pilots be vigilant as to what exactly is asked of them, they must also be alert to the fact that when several navaids are in close vicinity of an airport, they are issuing position reports from the correct NAVAID. Likewise, controllers should use common sense and question pilot reports which are obviously wrong or implausible.

Related reports:

Google
 

Original NASA ASRS Text

Title: NON RADAR APCH FAC ASKS FOR A POSITION REPORT FROM IFR ACFT AND RECEIVES AN ERRONEOUS DISTANCE FROM NAVAID RESULTING IN LESS THAN STANDARD SEPARATION WITH OPPOSITE DIRECTION TRAFFIC.

Narrative: ATX X TRACKING INBND ON DAK 220 RADIAL TO THE VOR TO EXPECT APCH TO FYV ARPT, DESCENDING TO 6000 MSL. ATX Y CLIMBING OUT OF FYV ARPT, SWBND TO 5000 MSL. TRAINEE ON POSITION, WORKING TFC. ABOUT 2 MINS AFTER DEP, TRAINEE ASKS ATX X FOR POSITION FROM DAK. THE REPLY IS THE 220 RADIAL AT 16 DME. TRAINEE THEN ASKS MTR 814 HIS POSITION FROM DAK TO ESTABLISH TAIL-TO-TAIL SEPARATION OF OPPOSITE DIRECTION TFC. ATX Y REPLIES 193 RADIAL AT 20 DME. TRAINEE ASSUMED THE POSITION REPORT FROM ATX Y WAS CORRECT AND PROCEEDED TO CLIMB ATX Y TO 9000 MSL. INSTRUCTOR IMMEDIATELY ISSUED INSTRUCTION TO THE ATX Y TO MAINTAIN 5000 MSL, WHEREUPON THE PLT OF ATX Y REPLIED HE HAD OPPOSITE DIRECTION TFC STRAIGHT AHEAD (ATX X). THE PRIMARY ERROR HERE WAS THE ERRONEOUS REPORT FROM ATX Y. THE RZC VORTAC IS LOCATED 15 DME N OF THE FYV ARPT AND IS USED AS THE PRIMARY APCH FIX FOR THE FYV AIRSPACE. DAK VOR IS A TERMINAL VOR LOCATED 2.2 DME NW OF FYV ARPT. ACFT CLRED FROM FYV TO JOIN V63 OFF RZC, SWBND, OFTEN NAVIGATE OFF RZC AFTER DEP FROM FYV. INBND TFC TO FYV FROM THE SW USUALLY NAVIGATE FROM THE DAK VOR. OFTEN PLTS IN THE SW QUADRANT OF THE AIRSPACE ARE CONFUSED OR FORGET WHICH NAVAID THEY ARE NAVIGATING FROM. IN THIS CASE, ATX Y, SWBND TO JOIN V63, WAS NAVIGATING FROM RZC, AND WHEN HE WAS REQUESTED TO REPORT HIS POSITION, HE REPLIED THE 193 RADIAL AT 20 DME -- THIS POSITION WAS OFF RZC, NOT DAK. TRAINEE DID NOT REALIZE THE IMPLAUSIBILITY OF A TURBOPROP COVERING 20 MI IN 2 MINS, ASSUMED THE POSITION REPORT WAS CORRECT, AND PROCEEDED TO CLIMB THE ACFT IN FRONT OF THE INBND ATX X ACFT. THIS HAPPENS QUITE FREQUENTLY IN OUR AIRSPACE, AND OWING TO ITS LACK OF RADAR, THE CTLR AT FYV MUST RELY ON COMMON SENSE TO ASCERTAIN WHETHER OR NOT A PLT REPORT IS INDEED ACCURATE, OR IF THE REPORT APPEARS TO BE WAY OFF BASE. IN THIS CASE, THE INSTRUCTOR'S EXPERIENCE CAME INTO PLAY TO AVERT A POTENTIAL MIDAIR COLLISION, ONCE HE RECOGNIZED THE IMPOSSIBILITY OF ATX Y'S POSITION REPORT. NOT ONLY MUST PLTS BE VIGILANT AS TO WHAT EXACTLY IS ASKED OF THEM, THEY MUST ALSO BE ALERT TO THE FACT THAT WHEN SEVERAL NAVAIDS ARE IN CLOSE VICINITY OF AN ARPT, THEY ARE ISSUING POSITION REPORTS FROM THE CORRECT NAVAID. LIKEWISE, CTLRS SHOULD USE COMMON SENSE AND QUESTION PLT REPORTS WHICH ARE OBVIOUSLY WRONG OR IMPLAUSIBLE.

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.