EMB ERJ 135 ER/LR
Air Traffic Control Fully Certified
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Air Traffic Control Issued Advisory / Alert; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Became Reoriented
Human Factors; Procedure
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.
On approach into OMA; we were vectored for a right downwind to a visual approach to Runway 14R. Approach told us that we were following traffic 2 o'clock 3;000 FT. We looked where ATC had directed us and immediately picked up what we thought was our traffic. We acknowledged to ATC that we had the traffic in sight and ATC cleared us for a visual following traffic. I waited for the traffic we had identified to be abeam the jet and I turned base. ATC told us that we were 40 knots faster than traffic so I put thrust to idle slowed to 180 and continued the base. Thirty seconds later ATC again told us that we were still 40 knots faster than the preceding traffic we dropped the gear and put in flaps 22 and I started to slow to final approach speed. We noted that ATC's notification was strange because the traffic we were following was almost touching down on the runway and there was plenty of space between us. That was when I noticed motion from 11 o'clock coming to 12 o'clock an MD-80 crossing in front of us 4 miles out. Approach was giving us a frequency change to Tower at the same moment. I turned out to widen my base and stopped my descent. I told the First Officer I was going to level here and fly through the final approach course to get more separation. The First Officer contacted Tower and told them that we had been following the wrong aircraft. Tower said that flight through final was approved and that a right hand 270 to rejoin the final was also approved. We flew out; kept an eye on the traffic we had just became aware of; and turned back in to land without event. The threats were that we assumed we had the correct traffic because the weather was so nice and we immediately identified an aircraft at the position and altitude where Approach directed us to look. We were not told that there were two aircraft out there and we only heard one other jet on the frequency because I assume the jet we were following in error had already been switched to Tower. Another threat is that the jet that we immediately picked out was a white widebody aircraft making it easily visible; while the one we were intended to pick up was a grey MD-80 that was fairly well hidden against the backdrop of Council Bluffs and the grey leafless trees. ATC told us twice that we were 40 knots faster than the aircraft we were following but it was never brought to our attention that we had turned inside of the aircraft that we were actually supposed to be following. I would think that if ATC had seen us turn in the way we did on radar they would have said something sooner. Even after we noticed the new threatening aircraft; Approach was giving us a handoff like everything was fine. Vigilance is key. We messed up in missing the other aircraft. We were sure and vocally agreed that we had the aircraft we were supposed to see in sight and I was focused on following that traffic and getting into position to shoot a good visual approach. I should have checked final more frequently and maybe I would have seen the aircraft that we were unaware of sooner.
The EMB145 pilots and the two controllers involved describe a technical loss of separation incident during a visual approach to Runway 14R at OMA.