Narrative:

Minot AFB approach control does not open until 7:00am CST on monday mornings. While we do have a frequency at mot we do not have complete radar coverage until between 25 and 30 miles southeast of the mot VOR. Due to an oil boom in north dakota; mot sees a fair amount of traffic early in the morning. A crj-200 requested clearance and was issued one departing mot to msp via far as filed. I had 2 inbound aircraft to mot that were greater than 60 miles away at the time the clearance was issued. I had descended a cessna 441 down to 11;000 feet MSL and when the crj-200 departed mot I climbed him to 10;000 feet. Intending to separate them in radar. Initially I was using altitude separation. I informed the descending C441 that I had departing traffic not within radar; I then radar identified the crj. The crj and the C441 advised they had each other insight. The C441 then said he lost the crj because the aircraft turned off their landing light. Then C441 said he had the crj back in sight as the aircraft had turned their landing light back on. I had the C441 restate they had the crj in sight and then advised the C441 to maintain visual separation from the crj and to descend to 5;000. The C441 read back that he would maintain visual from the crj and 050. I let the crj know the C441 had him in sight and was maintaining visual separation in a descent. I am nearly positive the C441 read back his call sign correctly when reading back the visual separation clearance. But in the back in forth of establishing him having the crj in sight I may have missed it. About the time the C441 passed off the side of the crj; the pilot of the crj advised me they had received an RA that the C441 had passed a little close to them and they responded with a slight turn off course but were now correcting back to course. I asked the pilot if he needed anything else; he said no. I advised my supervisor of the RA. The pilot did not sound alarmed or upset. Once standard separation was restored I climbed the crj to his flight plan requested altitude. When I applied visual separation I did not issue that 'targets appear likely to merge.' it looked as if the range I was operating on the targets would just pass off each others right sides. After the crj advising me of the RA I find it would have been prudent to advise the pilots 'targets appear likely to merge' as a precaution. Recommendation; it would be preferred to have minot AFB radar piped into our radar system to make the flow of traffic in and out of mot more efficient when minot AFB RAPCON is closed. I will start applying 'targets appear likely to merge' when I think aircraft will be less than 2 miles apart due to mosaic radar limitations.

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Original NASA ASRS Text

Title: ZMP Controller described a conflict event with aircraft operating to/from MOT during the TRACON's closure; the reporter noting that having access to MOT RADAR would prevent these types of occurrences.

Narrative: Minot AFB Approach Control does not open until 7:00am CST on Monday mornings. While we do have a frequency at MOT we do not have complete RADAR coverage until between 25 and 30 miles southeast of the MOT VOR. Due to an oil boom in North Dakota; MOT sees a fair amount of traffic early in the morning. A CRJ-200 requested clearance and was issued one departing MOT to MSP via FAR as filed. I had 2 inbound aircraft to MOT that were greater than 60 miles away at the time the clearance was issued. I had descended a Cessna 441 down to 11;000 feet MSL and when the CRJ-200 departed MOT I climbed him to 10;000 feet. Intending to separate them in RADAR. Initially I was using altitude separation. I informed the descending C441 that I had departing traffic not within RADAR; I then RADAR identified the CRJ. The CRJ and the C441 advised they had each other insight. The C441 then said he lost the CRJ because the aircraft turned off their landing light. Then C441 said he had the CRJ back in sight as the aircraft had turned their landing light back on. I had the C441 restate they had the CRJ in sight and then advised the C441 to maintain visual separation from the CRJ and to descend to 5;000. The C441 read back that he would maintain visual from the CRJ and 050. I let the CRJ know the C441 had him in sight and was maintaining visual separation in a descent. I am nearly positive the C441 read back his call sign correctly when reading back the visual separation clearance. But in the back in forth of establishing him having the CRJ in sight I may have missed it. About the time the C441 passed off the side of the CRJ; the pilot of the CRJ advised me they had received an RA that the C441 had passed a little close to them and they responded with a slight turn off course but were now correcting back to course. I asked the pilot if he needed anything else; he said no. I advised my Supervisor of the RA. The pilot did not sound alarmed or upset. Once standard separation was restored I climbed the CRJ to his flight plan requested altitude. When I applied visual separation I did not issue that 'targets appear likely to merge.' It looked as if the range I was operating on the targets would just pass off each others right sides. After the CRJ advising me of the RA I find it would have been prudent to advise the pilots 'targets appear likely to merge' as a precaution. Recommendation; it would be preferred to have Minot AFB RADAR piped into our RADAR system to make the flow of traffic in and out of MOT more efficient when Minot AFB RAPCON is closed. I will start applying 'Targets appear likely to merge' when I think aircraft will be less than 2 miles apart due to mosaic RADAR limitations.

Data retrieved from NASA's ASRS site as of July 2013 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.