Air Traffic Control Developmental
Communication Breakdown
ATC Issue All Types; Conflict NMAC; Deviation - Speed All Types
Human Factors; Procedure; Aircraft
The event I am reporting actually occurred after I left the D-side position; but I made other controllers aware of the aircrafts involved about 10-15 minutes prior to the event. There were two aircraft; one VFR and one OTP that were operating en route at the same altitude; 085. I told the Controller I briefed that I was watching the aircraft because they were about 10 miles apart and same altitude and the back aircraft was a little bit faster (about 20 KTS or less). The Radar Controller ran a route line to illustrate where the aircraft were going. About 10 minutes later; the Radar Controller was relieved by the Controller that relieved me on the D-side; combining the two positions since traffic had started to die down and the R-side had been in for about an hour and 30 minutes. At about that time; a little after; the two aircraft got within a mile at the same altitude while they were in Sector 42's airspace; but talking to Seattle Center Controller. No traffic calls were made by either of the R-side controllers and the VFR aircraft said that he was going to file a 'near mid-air collision report.' The session leading up to this event was characterized by heavy traffic; VFR and IFR; multiple approached being made; and a newly certified R-side Controller. I am a CPC-IT here at ZOA; I am certified at both the D-side and R-side positions of this sector. The sector is characterized by mountainous terrain; lots of military use airspace; and a mix of IFR inbound/outbound from the Bay Area; as well as numerous VFR's maneuvering and flying through. This sector is complex; because the VFR's become a huge responsibility; along with all the other things going on for IFR aircraft. Also; a lot of aircraft will opt to go VFR on top (OTP) to avoid re-routes and altitude changes for the terrain. I think that this sector and Sector 40 both are very different from other low airspace that I have worked; due to the VFR complexity; and there need to be specific outlines for responsibilities concerning VFR and OTP aircraft communicated to controllers.
ZOA Controller describes situation where two aircraft come close to each other and one of the pilots declares a NMAC.