Stratolifter (C-135 / 717)
Air Traffic Control Fully Certified
Communication Breakdown; Situational Awareness
ATC Issue All Types; Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Human Factors; Weather
While working [Sector X] D-Side; a Stratolifter entered our airspace inbound for the air refuling track. I told the R-Side about it and he said OK. Once the Stratolifter entered our airspace the R-Side tried to descend him down because we had multiple aircraft that were traffic with the Stratolifter. The Stratolifter stated that they would like to stay up for whatever reason; possibly for weather. The R-Side amended the altitude to FL310 and assigned a vector to the Stratolifter for traffic; approximately a 190 heading. The Stratolifter flew the heading for a couple of moments then came back and said he would rather descend and go back on course. The R-Side then cleared the Stratolifter back to the initial fix on air refuling track and descended the aircraft to FL240. The R-Side already knew about the traffic at FL290; a Medium Large Transport; which was the reason for the initial vectors. I advised the R-Side of the traffic at FL240 and asked if he would like me to call [Sector Y] and put that aircraft on a heading. Conflict Alert goes off almost immediately after he gave the clearance back on course and descent. The R-Side then attempted to vector the Medium Large Transport out to a 150 heading and we were unclear if the aircraft got the clearance or not due to known frequency problems in this sector. It took multiple clearances before the Medium Large Transport acknowledged the vector. The R-Side then tried to go back and vector the Stratolifter back to the south and once again it took multiple clearances due to bad frequency issues. By the time the vectors were acknowledged it may have been too late. I then tried to contact [Sector Y] to let them know what was happening. It took them several minutes before they answered their line. So a lot of this stuff that happened; I missed; due to that. The Medium Large Transport then went NORDO and traveled for about 5-10 minutes before [the neighboring] Center regained communications with the aircraft. Later while talking to the R-Side about what happened; he stated that the Stratolifter turned back on course a lot faster than he anticipated. We need to get the frequencies in [Sector Z] fixed. Also; I don't know why the Stratolifter wanted to stay at FL330 for so long; and as soon as he was turned off course he wanted a descent. Maybe we need to standardized procedure with these aircraft that way we can know what to expect.
I was working [Sector X; R-Side] and had turned a Stratolifter out to a 195 heading for his upcoming descent. A Medium Large Transport was the southbound traffic at FL290 I was missing. The Stratolifter flight; when I turned him back on course; made a pretty tight turn to cause the confliction. We did have some frequency issues which resulted in the Medium Large Transport being left on a 150 heading until we went thru his company and got the aircraft onto the next sector. I initiated turns which resulted in the aircraft being right on the bubble until the turns took effect. I should have left the Stratolifter flight on the 195 heading until he left FL280. The frequency has had lots of static on it lately which did not help matters any when trying to contact the aircraft.
Enroute Controller described a conflict event when an air carrier delayed a descent; likely due to weather; and then turned tighter than expected; adding to the problems were communications difficulties.