Widebody Transport
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 10.0
Communication Breakdown; Time Pressure; Situational Awareness
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic
ATC Equipment / Nav Facility / Buildings; Company Policy; Human Factors
Our frequency transmitters have gotten noticeably worse in their range over the past several months; especially when in the mid-shift configuration. This was the primary cause of the loss of separation in my mind. I was working combined sectors at the mid setting. Aircraft Y was close to the sector boundary; and needed a handoff soon. Conflict alert went off with Aircraft X in the other sector's airspace; southwest bound into my airspace. I turned Aircraft Y to the left; as I needed to turn him anyway for route requirements. He did not respond. The Sector called me as I was issuing this turn; and had begun a turn to heading 200 on Aircraft X and was coordinating. I tried Aircraft Y again to turn him to the left to ensure separation. And then again; using a different transmitter; same result. At this point Aircraft X checked on heading 200. I responded; and was going to turn him further; but I thought it would be better to try Aircraft Y again since I knew he was on frequency. Again he did not respond.And then Aircraft Y checked on again; indicating he did not hear me respond to him the previous time. This was the point where I realized that we were [expletive]. So I just gave him a traffic call for his traffic; and that time he said roger. When he responded; and Aircraft Y finally responded; it was too late to take any further measures. It was a controlled situation; and the separation; while not the full 5 miles; was enough to not actually affect any aircraft safety whereas an immediate descent would definitely have. Fix the [expletive] radios. There are four transmitter sites for our mid frequency. Now every single one of the transmitters has horrible static issues and worse area coverage than ever. We have made countless complaints; but they fall on deaf ears. The only work that has been done is 'we will try resetting them;' to no avail. They really need to figure out what happened; and fix it so that something like this can be prevented.
ZDV ARTCC Controller reported being unable to communicate with aircraft due to faulty transmitters during mid-shift while working combined sectors.