Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2
Communication Breakdown
ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Separated Traffic; Air Traffic Control Provided Assistance; Flight Crew Took Evasive Action
Procedure
D01 coordinated to bring Aircraft X in through the NW corner of the airspace at 120 to avoid some glider activity around Kelly Air Park (off the LOA).  This aircraft was already 5-10 miles from the NW corner and pointed at COS.  Aircraft Y has been doing aerial survey lines VFR extending 15 miles N of COS to 10-15 miles S of COS for several hours at 145 or higher.  VFR Aircraft Z had an inoperative Mode C and was transitioning from somewhere south of PUB to APA.  Aircraft Z was restricted to 115 due to the inoperative Mode C. Other aircraft were in other parts of the airspace as well.  Aircraft Y advised that he was finished with his survey lines and was ready to return to base while at 130.  I tried to turn him to a heading of 030 to get him out of the arrival corridor for his descent and told him to descend to 110.  However; he advised that he was not done with his lines and still had to continue on a line.  I told Aircraft Y to continue his line; but forgot to advise him stop his descent.  Aircraft Y continued N; then turned NW while descending.  I had to issue a vector to Aircraft Z to keep him out of the AFF airspace; and he requested to descend.  I agreed; and then issued traffic.  I turned Aircraft X to H110 to descend him and avoid the Aircraft Z; then realized that Aircraft Y had finished his line and started descending--taking a turn I did not anticipate.  Aircraft X initiated a TCAS RA for Aircraft Y; who was about 1.5 miles S of him. Aircraft Y had Aircraft X in sight; but I do not remember if it was before/after the TCAS RA.I was likely fatigued because I was trying to get training for a trainee and took very few breaks to make this happen.  I tried to ensure breaks for the other CPC and trainee; at my own expense.  In hindsight; this may not have been the best plan with regards to myself.  I could have also prevented this if I had required D01 to bring Aircraft X in on the LOA--which would have brought him in on the E side of the airspace; long after Aircraft Y and Aircraft Z.
COS Controller reports that due to accepting an aircraft on other then LOA procedure they ended up having an operational error and TCAS RA Event.