Commercial Fixed Wing
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Altitude Excursion From Assigned Altitude
Flight Crew Took Evasive Action
Airspace Structure; Human Factors; Aircraft
On right downwind vector to RWY 14R at OMA while descending from 4000 FT and approaching 3000 FT; First Officer (Pilot Monitoring) alerted Captain (Pilot Flying) of TCAS target closing and climbing quickly 600 ft below. At 400 ft below; Captain exercised emergency authority and performed evasive climb. Target came within 300 feet and 1/2 mile. Target was never visually acquired. First Officer notified ATC that we were climbing; and ATC responded with traffic call indicating target was a Cessna and that he was within one half mile and had visual contact with us. Once clear of traffic; we were cleared for a visual approach to RWY 14R for uneventful landing. After landing Captain elected to have a conversation with ATC where we learned that the Cessna had departed an uncontrolled airfield VFR enroute to OMA and that ATC was surprised by the pop-up traffic. Although TCAS provided basic target info; it never gave us either a visual or oral 'Traffic' alert or 'RA'. TCAS was written up for maintenance evaluation. It appears that the approach pattern used by OMA Approach comes dangerously close to a nearby uncontrolled airfield with aircraft departing and arriving VFR and without the knowledge or control of ATC. Suggest review of OMA arrival patterns / altitudes to include possibility of conflicts with other airfields.
Air carrier Captain reported an airborne conflict in the vicinity of OMA with a corporate jet that had departed from a nearby non-towered airport.