Date: 201712
Local time of day: 1801-2400
Location: SEE.Tower, CA
Flight conditions: VMC
Light: Daylight
Aircraft: Super King Air 350
Operator: Military
Operating under: Part 91
Mission: Training
Flight phase: Initial Climb
Airspace: Class D SEE
ATC / advisory: Tower SEE
Second aircraft: S-70/UH-60 Blackhawk/Seahawk/Pavehawk/Knighthawk
Reporter organization: Government
Reporter function: Supervisor / CIC
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness; Distraction
Second reporter function: Local
Anomaly: ATC Issue All Types; Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Automation Air Traffic Control; Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Separated Traffic; Air Traffic Control Issued New Clearance
Contributing factors: Procedure; Airspace Structure; Human Factors
Primary problem: Procedure

Narrative: The Tower Local control positions were de-combined. Traffic was easterly operations. I was monitoring Local North. A VFR B350 was awaiting departure. I received a point out of a flight of two H60s that were transitioning from West to East that would definitely effect any North field traffic. I also anticipated the Helicopters to be traffic for any departures on the Northside. The Local North Controller issued traffic to the B350 that had departed referenced the H60s and a Cherokee. The B350 reported the Helicopter traffic in sight. Once I heard that the conflict appeared to be resolved; I resumed to assigning duties for the position rotation. The controller switched the B350 and advised TRACON that they were looking for the traffic.I was not aware of a Cessna inbound. The C172 was on the South Local Controller frequency. At the time; the ATM (Air Traffic Manager) was in the cab talking to other controllers about other things; and during the occurrence he was standing directly behind the two controllers on position watching them work; obstructing my view. If he saw something peculiar; he could have brought it to the attention of any one of us at the time. After the fact; the ATM discussed with me that the B350 did not have the Cessna in sight. I assume this was after he reviewed the audio. I explained to him that I was not aware of the C172 until after the audio and Falcon replay. Prior to this revelation; the North controller had called the Cessna a Cherokee but DID give the traffic call. I heard the collision alert; which alarmed well after the B350 was switched to the sector. I heard externally the South Controller give traffic alerts to a Cessna that appeared to be not answering. The controller was making transmissions to provide the traffic. The controllers (and I am not sure if they did; you cannot hear from my distance) could have coordinated the Cessna and B350 intentions. If I had known in time about the Cessna; I could have suggested to the Local South controller to give a suggested VFR heading i.e. (for more positive control) vice the 'turn southbound' instruction. I would recommend a group review of the situation with all parties involved to discuss; learn and prevent any possible future re-occurrence.Having an ATM in the cab and talking to other controllers; and then literally standing behind the local controllers watching them; while they were working traffic during that event; may have been a contributing Human Factor to their performance. Especially when they are working [non]- standard operation.


Second narrative: Local positions were split. Local North controller asked if I could take a Cessna 172 inbound for touch and go. I agreed and the Cessna was switched to me the Local South position. Upon contact; I saw a King Air 350 climbing off and instructed the Cessna to turn south for that traffic. I made a few traffic calls; the final one being a traffic alert. The King Air was already transferred to approach control. The Cessna never saw the King Air. They passed over each other and it appeared to both be at 3400 feet. The only thing would maybe to have kept King Air on frequency until traffic had passed by other controller.


Synopsis: ATC Tower Supervisor and Local Controller reported a NMAC.