Date: 201501
Local time of day: 1201-1800
Location: HIO.Tower, OR
Light: Dusk
Aircraft: Helicopter
Operating under: Part 91
Flight phase: Cruise
Airspace: Class D HIO
ATC / advisory: Tower HIO
Second aircraft: Helicopter
Reporter organization: Government
Reporter function: Supervisor / CIC
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Distraction; Situational Awareness; Workload; Confusion; Communication Breakdown
Second reporter function: Local
Anomaly: ATC Issue All Types; Airspace Violation All Types; Conflict NMAC; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Took Evasive Action
Contributing factors: Airspace Structure; Aircraft; Human Factors; Procedure
Primary problem: Procedure

Narrative: While working CIC; I was working with the Hillsboro fire department personnel in the tower cab checking on the communication radio when I heard the local 2 controller say something about traffic over alpha in his airspace. As I looked up there was another helicopter talking to the other local controller that had been departed westbound via the alpha taxiway. I told the local controller that the alpha pattern was hot. Later the pilot of Aircraft X called and said that she got within 100 ft. of the other 1st; the preferred departure routing for noise with the port of Portland is westbound over the alpha taxiway. This regularly conflicts with other helicopter traffic in the alpha helicopter patters working on a different frequency with another controller. A different departure route should be used.2nd; currently there is no requirement to verbally coordinate via landline coordination to cross through another controllers airspace within the facility. All use of another controller's airspace should be coordinated via the landline between local control positions.


Second narrative: Our operation staffs the Local Control (LC) position to work the runways and fixed wing and HELOs departing; arriving; or transitioning our airspace. HELOs operating in accordance with our HELO LOA remaining in the airspace for pattern work communicate with Local 2 (LC2).HIO SOP dictates that LC2 does not own any airspace/movement areas until coordination for control of needed airspace/movement area is complete with LC or Ground Control (GC); respectively. In accordance with the 7110.65 [and] HIO SOP; LC and GC must request from LC2 use of surrendered airspace/movement area if need for their operation(s). LC2 gives LC and GC airspace/movement areas back when the HELO(s) have terminated their use of the pattern.Our LOA with our flight school (located in the SE corner of the airport abeam the left approach end of RWY 31) allows HELOs to depart West/Northwest from TWY A. 'Alpha' pattern is a local term for HELOs to use TWY A for pattern work. The HELO pattern is restricted to the west side of the airport/TWY A between the Control Tower and departure end of RWY 31. The Controller working LC during this event had relieved the Controller who gave me (LC2) control of 'Alpha' about 10/15 minutes prior to this event. The relieved Controller did brief the relieving Controller (LC) that 'Alpha' was active; memory aid was in place; and two minute overlap was compete. Additionally; besides the CIC and GC; two firefighters were in the cab maintaining a radio use for communications during an alert.'Alpha' was active for Aircraft X in left traffic. I observed an Aircraft Y pass in front of the tower NW bound over TWY A which at first I believed was Aircraft X completing a circuit. Rather; LC forgot ''Alpha' was active and cleared Aircraft Y for take-off from TWY A NW bound. It was not until I observed Aircraft X turning from base to final abeam the tower that I realized the conflict and issued traffic to Aircraft X. Aircraft X took evasive action to avoid Aircraft Y.After speaking with both Aircraft X and Aircraft Y pilots via landline; Aircraft X advised they had not seen Aircraft Y until after I issued the traffic. Aircraft X pilot also estimated only 100' separation above and behind Aircraft Y. Aircraft Y advised they did not see Aircraft X at any point and did not realize a conflict had occurred until they returned to the airport from their VFR practice flight. Both aircraft are based at the same flight school.These aircraft operations at our airport have always been a 'sensitive' topic. Numerous work groups have come together to visit and prevent these situations. I personally would like to see published routes which keep these aircraft operating in the pattern away from other departing/arriving out/in of the airspace moreover all fixed wing traffic. Due to community noise sensitivity; I understand no party will agree to such routes.


Synopsis: HIO Controller reports of an airborne conflict between two helicopters and the lack of coordination required by Tower SOP to enter or use another position's airspace.