Narrative:

I was training a developmental controller on radar west position combined with radar final sector at wichita TRACON. We had air carrier X, trner, established on the ILS to runway 19R at 3000', air carrier Y was being vectored on a left downwind for a visibility approach to runway 19L at 5000', and still in the clouds. The developmental controller descended air carrier Y to 3000' and turned him westbound on a base to runway 19L. Aircraft had to be at the MVA in order to see the airport. I saw the potential conflict and decided to let the developmental work it out on his own, after calling his attention to the situation. He called traffic to both aircraft, and they saw each other, and he instructed each to maintain visibility sep with the other. Air carrier Y made a wide turn to final, flying through the final for runway 19L, and it was apparent that the targets were going to merge at the same altitude. Because I feared a mid-air collision despite the aircraft maintaining visibility sep, I instructed air carrier Y to pass above air carrier X (I overrode the developmental in making the transmission). When he climbed, air carrier Y entered the clouds (according to air carrier Y pilot) and mode C readouts were approximately 200' apart. Causes. Developmental controller placing 2 aircraft in a position difficult to maintain visibility sep and instructing them to do so; my failure to properly prevent the occurrence in a timely manner. Failure of the flight crews to refuse visibility sep responsibility when they were unable to do so. Advertising visibility approachs when WX conditions precluded doing so safely. Callback conversation with reporter revealed the following information. Reporter experience, 2 yrs radar, 1 yr non-radar. Reporter stated the trnee controller was having problems getting through the training program. The trnee has been terminated as an ATC specialist. This was the reason he allowed the trnee to go as far as he did. The trnee used proper procedure and instructed air carrier Y to maintain visibility sep from air carrier X. Air carrier Y pilot accepted the clearance. The reporter and flight crew of air carrier Y discussed the operation on the frequency, however there were no formal reports filed by the flight crews or the FAA.

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Original NASA ASRS Text

Title: ACR Y FAILED TO MAINTAIN VISUAL SEPARATION FROM ACR X. ACR Y REENTERED IMC WHILE MAINTIANING VISUAL SEPARATION. PLTDEV.

Narrative: I WAS TRNING A DEVELOPMENTAL CTLR ON RADAR W POS COMBINED WITH RADAR FINAL SECTOR AT WICHITA TRACON. WE HAD ACR X, TRNER, ESTABLISHED ON THE ILS TO RWY 19R AT 3000', ACR Y WAS BEING VECTORED ON A L DOWNWIND FOR A VIS APCH TO RWY 19L AT 5000', AND STILL IN THE CLOUDS. THE DEVELOPMENTAL CTLR DSNDED ACR Y TO 3000' AND TURNED HIM WBND ON A BASE TO RWY 19L. ACFT HAD TO BE AT THE MVA IN ORDER TO SEE THE ARPT. I SAW THE POTENTIAL CONFLICT AND DECIDED TO LET THE DEVELOPMENTAL WORK IT OUT ON HIS OWN, AFTER CALLING HIS ATTN TO THE SITUATION. HE CALLED TFC TO BOTH ACFT, AND THEY SAW EACH OTHER, AND HE INSTRUCTED EACH TO MAINTAIN VIS SEP WITH THE OTHER. ACR Y MADE A WIDE TURN TO FINAL, FLYING THROUGH THE FINAL FOR RWY 19L, AND IT WAS APPARENT THAT THE TARGETS WERE GOING TO MERGE AT THE SAME ALT. BECAUSE I FEARED A MID-AIR COLLISION DESPITE THE ACFT MAINTAINING VIS SEP, I INSTRUCTED ACR Y TO PASS ABOVE ACR X (I OVERRODE THE DEVELOPMENTAL IN MAKING THE XMISSION). WHEN HE CLBED, ACR Y ENTERED THE CLOUDS (ACCORDING TO ACR Y PLT) AND MODE C READOUTS WERE APPROX 200' APART. CAUSES. DEVELOPMENTAL CTLR PLACING 2 ACFT IN A POS DIFFICULT TO MAINTAIN VIS SEP AND INSTRUCTING THEM TO DO SO; MY FAILURE TO PROPERLY PREVENT THE OCCURRENCE IN A TIMELY MANNER. FAILURE OF THE FLT CREWS TO REFUSE VIS SEP RESPONSIBILITY WHEN THEY WERE UNABLE TO DO SO. ADVERTISING VIS APCHS WHEN WX CONDITIONS PRECLUDED DOING SO SAFELY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. RPTR EXPERIENCE, 2 YRS RADAR, 1 YR NON-RADAR. RPTR STATED THE TRNEE CTLR WAS HAVING PROBS GETTING THROUGH THE TRNING PROGRAM. THE TRNEE HAS BEEN TERMINATED AS AN ATC SPECIALIST. THIS WAS THE REASON HE ALLOWED THE TRNEE TO GO AS FAR AS HE DID. THE TRNEE USED PROPER PROC AND INSTRUCTED ACR Y TO MAINTAIN VIS SEP FROM ACR X. ACR Y PLT ACCEPTED THE CLRNC. THE RPTR AND FLT CREW OF ACR Y DISCUSSED THE OPERATION ON THE FREQ, HOWEVER THERE WERE NO FORMAL RPTS FILED BY THE FLT CREWS OR THE FAA.

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.