Small Aircraft
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (mon) 6
Situational Awareness; Workload; Distraction; Confusion; Communication Breakdown
ATC Issue All Types; Conflict NMAC; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance
Flight Crew Took Evasive Action
Human Factors; Procedure
Local North (LCL-N) had a couple aircraft in the north pattern on runway 7L. Aircraft X was in the pattern and upwind when Local South (LCL-S) coordinated with LCL-N and requested LCL-N take the 7R upwind aircraft in left closed traffic for runway 7L. LCL-N approved the request with no restrictions.Aircraft X was about 1 mile off the departure end and already on left crosswind when Aircraft Y; about 1/2 mile off the departure end turned left crosswind. I pointed out to LCL-N controller that Aircraft Y was cutting out Aircraft X. Aircraft Y checked on with LCL-N controller. LCL-N acknowledged Aircraft Y; but did not issue any control instructions. A few seconds later the controller issued traffic to Aircraft X and told them to fly a wide downwind. Aircraft X replied that they initially did not have the traffic but in the same transmission they saw Aircraft Y a few hundred feet away at the same altitude still on left crosswind and Aircraft X made a sharp right turn to avoid Aircraft Y. The controller watched the situation but took no real action or have any control instructions. After Aircraft X had turned back to the downwind abeam Aircraft Y the controller sequenced Aircraft X to follow Aircraft Y. I estimated the aircraft to be less than 300 feet of each other when Aircraft X took evasive maneuvers.I am not sure what should be done to correct this sort of thing. Without knowing why the controller approved LCL-S controller's request or why they did not take any further action and allowed the incident to become unsafe it is hard to say what corrective action is needed. I believe this incident was more a result of controller skill level and ability to keep track of traffic.
DVT Tower Controller reported a Near Mid Air Collision. Reporter stated the skill level of a colleague contributed to the event.