Incident Overview
On a med-evac flight from Victoria, British Columbia, to Vancouver Harbour, a Helijet International Incorporated Sikorsky S-76A helicopter (C-GHJL) was operating under instrument flight rules (IFR). At approximately 1315 Pacific daylight time, the Victoria terminal controller cleared the helicopter to descend from 3000 to 2200 feet in the vicinity of Active Pass. Shortly thereafter, the controller alerted the crew that an opposite-direction radar target was one nautical mile ahead, previously undetected. The helicopter crew immediately spotted an aircraft landing light directly ahead and took evasive action to the right.
The opposing traffic was a Harbour Air Ltd. de Havilland DHC-3 (C-FRNO) on a visual flight rules (VFR) flight from Vancouver Harbour to Victoria Harbour. The pilot had just established contact with the Victoria tower outer airport controller, was levelling at 2500 feet approximately one nautical mile north of Active Pass, and was cleared through the Victoria Airport control zone. The pilot was not advised of conflicting traffic but spotted the helicopter at his 12 o'clock position less than one nautical mile away, in an evasive maneuver. The Otter did not take evasive action. Radar data showed both aircraft passing approximately two nautical miles south of the Active Pass NDB at 2700 feet with less than 600 feet lateral spacing.
The helicopter was operating within Class C airspace along an unpublished company area navigation (RNAV) route that crosses a published southbound VFR route near the Active Pass NDB. It had commenced descent with the intention of cancelling IFR and following a low-level transit route. The helicopter did not have a landing light on for cruise flight due to its downward orientation.
Air Traffic Control Context
The incident occurred in Class E transition airspace where VFR aircraft may operate without a transponder or communication. Controlled IFR flights are routinely cleared into the same airspace as uncontrolled VFR targets. Radar traffic information and conflict resolution between IFR and VFR aircraft in Class E airspace are not priorities; controllers provide such information only when workload permits. In this occurrence, the controller's attention was divided among numerous tasks, likely causing his radar-scanning technique to deteriorate. He did not detect the Otter's presence before issuing the descent clearance. Traffic information was provided but not in time to prevent the risk of collision.
Visual Detection Challenges
When the helicopter received the descent clearance, altitude separation was removed. Neither crew had been advised of the traffic, leaving only unalerted visual scanning as a defence. Weather conditions may have contributed to difficulty in visual detection. The helicopter crew spotted the Otter only after being alerted by ATC, while the Otter pilot spotted the helicopter on his own but without timely warning. The use of aids like traffic advisories, TCAS, or landing lights could have assisted detection. TCAS would likely have alerted both pilots, but neither aircraft was equipped with it. The Otter had its transponder on as it intended to enter Class C airspace, but transponders are not required in basic Class E airspace, limiting the potential safety benefit of TCAS.
Findings
The investigation found that the controller did not detect the Otter, possibly due to divided attention. Traffic advisories were not provided in a timely manner, impairing pilots' ability to detect the other aircraft. The altitude deviation by the Otter contributed to the risk but was not causal. Both operators and NAV CANADA had ongoing discussions about traffic conflicts, and an airspace study was initiated.