HS 125 Series
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 3
Communication Breakdown; Situational Awareness
ATC Issue All Types; Conflict NMAC
Air Traffic Control Provided Assistance; Flight Crew Returned To Clearance
Human Factors
Aircraft X was on a VOR/DME to Runway 34. We then had Aircraft Y; inbound from the north. LC1 had Aircraft Y cross over the field to enter the downwind for Runway 34; to avoid the wake turbulence from Aircraft X's circle. Once Aircraft Y had established himself in the downwind at 020 ft; Aircraft X was on a 1 mile final; at approximately 027 ft; and claimed to still have the runway in sight. At this point; I told the Local Controller that he was not going to be able to land; and to climb him to 030 [feet]; in order to clear Aircraft Y. The LC1 controller felt it was more important to widen out Aircraft Y's downwind; to avoid Aircraft X. I instructed him again to climb Aircraft X; as he was still descending. The LC1 controller climbed him to 030; while I worked on coordinating a heading for Aircraft X. They both landed safely; after Aircraft X was vectored out for the Visual Approach; and Aircraft Y landed immediately after the go around. Aircraft Y pilot called later and informed us that Aircraft X came within 200 ft of him.Have a cutoff point. Had we climbed Aircraft X at a 1 mile final when he was too high; he would have been no factor for Aircraft Y.
Tower Controller reported an NMAC due to Local Controller's sequence of two aircraft.