Situational Awareness; Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict
General None Reported / Taken
Procedure; Human Factors
On descent in to SUN; passing approximately FL180; ATIS was obtained. I checked in with Salt Lake Center; advised them we had the ATIS; and requested the RNAV/GPS 31 W MENIN transition. We were cleared down to 11;000. Passing approximately 13;000 we were cleared for the RNAV/GPS 31 W; routing only; maintain 11;000. Inside of OREYE we were cleared to 9;000. We called the field in sight and were cleared for the Visual Approach to 31. ATC advised us that a Metroliner was not talking to him but said Tower was; was off to our left and would follow us. We both looked at the TCAS and saw the target at about our 10 o'clock position and 5 miles. Descending through 10;000 we received a TA immediately followed by a RA. The pilot flying complied with the RA and I advised Center we were in a 'TCAS CLIMB.' Center asked us if we could continue the approach and I said no. We were then cleared back to 11;000 and to make a left 360 to re-acquire to field for a visual. Rolling out on a 350 heading we called the field again and were cleared for a Visual Approach to 31. Center switched us over to Tower. We checked in with Tower and were asked for our DME from the field which I reported as 12. He asked us to report a 5 mile final. He then asked the Metroliner to report his DME; I believe it was 12 or 13. At this time the target on our TCAS went back to amber. Tower then initially used our call sign; he later corrected it to the Metroliner; to instruct the Metroliner to 'slow to minimum approach speed for separation from the Citation and report the traffic in sight.' The Metro said he didn't have the traffic in sight and was asked to execute a right 360. Only then did the target on our TCAS turn back to CYAN. At no time during this event did we visually acquire the traffic. At approximately 6 DME the Tower cleared us to land. On the roll out we were asked to expedite to B4 as the Metroliner was on a two mile final. We cleared the runway at B4 and taxied to the ramp uneventfully. Coordination between Center and Tower is critical. This is even more critical at mountainous airports located in tight valleys with little room to work with. This lack of communication put two aircraft at the same point; at the same time. Without TCAS this could have been a very bad situation.
Corporate traffic inbound to SUN described a TCAS RA event with pattern traffic; the reporter noting the event was apparently triggered because of a breakdown of communication between the Center (ZLC) and SUN Tower.