Fighter
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 7.6
Confusion; Situational Awareness; Training / Qualification; Workload
ATC Issue All Types; Conflict Airborne Conflict
Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
Airport; Environment - Non Weather Related; Human Factors
Locals were split and traffic was pretty complex with a number of high performance aircraft in the mix. I observed that Local 1 began to get a rush of inbound aircraft and at one point I overheard he had Aircraft X inbound for an overhead. Aircraft X initially called up a good distance from the airport; but with its high performance was rapidly overtaking a number of other aircraft that were also coming inbound. It appeared Local 1 became overwhelmed and did not have positive control over the aircraft turning final and at one point; seemed to lose awareness of the position of Aircraft X. Simultaneously the pilot began circling and making other evasive maneuvers; eventually reporting to the controller that he was maneuvering to avoid other conflicting traffic.Aircraft X was eventually brought inbound for the overhead and after the break; was in a position conflicting with traffic to the northeast of the airport.  Once again; it appeared positive control over the aircraft was lacking from the controller. The two pilots began exchanging their own intentions for avoidance (eg. 'I'll go high; you go low').  There was no specific mention of a NMAC or significant evasive action; but it seemed the traffic conflicts that developed between Aircraft X and other inbounds could have been handled better.During a heavy inbound rush; time to detect and correct developing conflicts can be limited. As a result it is important to remain conservative enough in our control decisions to maintain situational awareness; promptly correct situations that might not work; and keep positive control of the final. In hindsight some of the VFR aircraft requesting inbound should have probably been held outside the airspace or at least Aircraft X needed an altitude restriction to keep it above all the slower traffic it was overtaking.  Local 2 was open and available as an additional resource and might have been used more effectively to offload some arrivals and free up frequency time to work the high performance Aircraft X into the airport more safely. Getting overwhelmed by high performance traffic happens at times in the VFR tower environment; but we should learn from our past experiences and use that experience we gain to our advantage when we approach saturation in the future.  It's okay to hold aircraft outside the airspace until there's room and it is okay to deny an operation (overheads; pattern work; low approaches; etc.) until such a time as it can be accommodated safely and efficiently. It is important for controllers to avoid letting their ego get in the way of running a safe operation and instead use the additional tools and resources available to them to share their workload; reduce risk and provide optimum service to users of the NAS.
BJC Tower Controller observed the Local Controller not positively separating traffic in the pattern and heard aircraft communicating with each other to remain clear of traffic.