Narrative:

I was working ground control (ground control) and clearance delivery combined at the ground control position at the time of the loss of airborne separation between the EMB145 and the MD80. Visual approaches to runway's 14R and 14L were being made at the time of the event; with low level windshear advisories on the ATIS. The intended landing sequence was a heavy jet; the MD80; and then the EMB145. I looked up at the ground control stars scope and noticed that the EMB145 at 3;100 ft MSL was on the right base; closing fast; and was going to loose separation with the MD80 who was over the civra (IAF 14R) at 2;900 ft MSL. I asked local control (local control) if they were talking to the EMB145; and he was not at this time. I was unable to get the aircraft in sight at this time due to the smoke (several grass fires were burning in the area) and haze in the air. Utilizing the *T stars function I determined that the aircraft came within 1.75 NM while they had 200 ft of vertical separation. As the EMB145 checked on with local control the pilot first noticed the MD80; and requested to maneuver for separation. After the EMB145 landed I asked if there had been a TCAS maneuver; the pilot said that there was not one. The pilot further indicated that they thought that they were following the aircraft in the flare short final (the heavy) and did not see the MD80 till they started to check on with the tower (local control). I conveyed this information to the R90 TRACON supervisor on duty. R90 mistakenly thought that the EMB145 had the MD80 in sight; and had cleared him to maintain visual and to follow that aircraft.stop pushing the responsibility for separation on to the pilots; control the situation. Positive control leads to positive outcomes; vector for the downwind; not the base. Be more cautious/vigilant on days when there are challenging weather conditions like low level windshear; this was a poor time to increase that pilot's workload. Realize that on days when there is a strong wind from the west that planes need to be turned out of the wind to descend and reduce to approach speed in order to be in a stable platform for landing; this seems to be a recurring issue with overtaking aircraft due to a strong tail wind in the base. Our LOA with R90 states that pilot application of visual separation is to be denoted with a 'vs' stars spad entry; this was not entered in the EMB145's data block. Don't ship that aircraft to tower to appear to be in imminent risk; when in doubt; break them out. The R90 - oma LOA states that the R90 final vector controller is responsible for separation on final; frequency separation is not an approved form of IFR separation.

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Original NASA ASRS Text

Title: The EMB145 pilots and the two controllers involved describe a technical loss of separation incident during a visual approach to Runway 14R at OMA.

Narrative: I was working Ground Control (GC) and Clearance Delivery combined at the GC position at the time of the loss of airborne separation between the EMB145 and the MD80. Visual approaches to Runway's 14R and 14L were being made at the time of the event; with Low Level Windshear Advisories on the ATIS. The intended landing sequence was a heavy jet; the MD80; and then the EMB145. I looked up at the GC STARS scope and noticed that the EMB145 at 3;100 FT MSL was on the right base; closing fast; and was going to loose separation with the MD80 who was over the CIVRA (IAF 14R) at 2;900 FT MSL. I asked Local Control (LC) if they were talking to the EMB145; and he was not at this time. I was unable to get the aircraft in sight at this time due to the smoke (several grass fires were burning in the area) and haze in the air. Utilizing the *T STARS function I determined that the aircraft came within 1.75 NM while they had 200 FT of vertical separation. As the EMB145 checked on with LC the pilot first noticed the MD80; and requested to maneuver for separation. After the EMB145 landed I asked if there had been a TCAS maneuver; the pilot said that there was not one. The pilot further indicated that they thought that they were following the aircraft in the flare short final (the heavy) and did not see the MD80 till they started to check on with the Tower (LC). I conveyed this information to the R90 TRACON supervisor on duty. R90 mistakenly thought that the EMB145 had the MD80 in sight; and had cleared him to maintain visual and to follow that aircraft.Stop pushing the responsibility for separation on to the pilots; control the situation. Positive control leads to positive outcomes; vector for the downwind; not the base. Be more cautious/vigilant on days when there are challenging weather conditions like Low Level Windshear; this was a poor time to increase that pilot's workload. Realize that on days when there is a strong wind from the West that planes need to be turned out of the wind to descend and reduce to approach speed in order to be in a stable platform for landing; this seems to be a recurring issue with overtaking aircraft due to a strong tail wind in the base. Our LOA with R90 states that pilot application of visual separation is to be denoted with a 'VS' STARS spad entry; this was not entered in the EMB145's data block. Don't ship that aircraft to tower to appear to be in imminent risk; when in doubt; break them out. The R90 - OMA LOA states that the R90 Final Vector Controller is responsible for separation on final; frequency separation is not an approved form of IFR separation.

Data retrieved from NASA's ASRS site 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.