Flight Crew Air Transport Pilot (ATP)
ATC Issue All Types; Conflict Airborne Conflict
Flight Crew Took Evasive Action
Human Factors
We were in communications with Atlanta Center enroute to AGS. The tower was closed. The ceiling was reported clear and we had the airport in sight about 10 miles west of the airport and were cleared for a visual approach. As we set up for a 5 mile right base we saw a broken layer ahead and below us which would prevent us from maintaining VMC. We requested vectors for the ILS runway 17 approach and were given a left turn direct the initial approach fix and instructed to fly the full procedure. No altitude assignment was provided and we were at 1800 feet. The charted procedure requires an altitude of 2500 during the initial segment of the approach.Meanwhile; a small twin; which was originally instructed to hold at IRQ VOR since he was Number 2 for the airport; had cancelled IFR and was now on an approximately 10 mile final. He was no longer communicating with the controller. The controller did not provide any traffic advisories after clearing us direct the IAF (we may have been below radar coverage). We identified the conflict on TCAS when the small twin was 5 miles away and directly head-on and descending into us. A few seconds later; I initiated a right 90-degree turn. I had not yet initiated a climb to 2500 feet since I was concerned with separation from the VFR small twin. While in the turn; we received a TCAS TA followed a few seconds later by a descending RA and I began a descent. I estimate that the lateral separation from the small twin during closest approach was 1 nm and vertical separation of 200 feet. The near-miss occurred in VMC; above a cloud deck and I maintained visual contact with the small twin at all times. We subsequently completed the full ILS procedure for runway 17.The controller was busy; but he should have been aware of the location of the inbound small twin from the north and provided a vector or an altitude that would keep us away from the traffic. We heard the small twin cancel IFR; but we were never made aware of his position. After detecting the traffic on TCAS; and then visually; I disconnected the autopilot and began a turn. After being given I descend command by TCAS; I hesitated a little since we were already at 1800 feet and I had the traffic in sight as we were turning. Soon after; I received an 'increase descent' command with a 1000+ FPM descent and promptly complied. I realized; that I had neither the terrain nor the weather radar modes selected on the MFD. Since there was no weather; I should've had the terrain mode displayed. That would've also helped with overall situational awareness.In preparation for final approach; my MFD was initially on the 5-mile range. At a closure rate of 300-400 knots; things happen quickly. One of us should have set the MFD at a farther range to be more situationally aware of the traffic. This also highlights the importance of TCAS. Sometimes we are asked to dispatch with an inoperative TCAS. Seeing and avoiding is much more difficult in a jet so the company should understand the uneasiness many pilots feel when confronted with that decision.
Air carrier Captain reported a TCAS RA with a VFR aircraft when he was vectored for the ILS 17 at AGS.