Narrative:

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.

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Original NASA ASRS Text

Title: ZOA Controller describes situation where two aircraft come close to each other and one of the pilots declares a NMAC.

Narrative: 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.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.