Narrative:

[I was] on flight following with ATC pt mugu; [vicinity of fim]; 6500ft; westbound. [I was] acting as PIC; with another pilot (student) in right seat. Received warning 'traffic at 1 o'clock; 6500 feet; heading northeast; type unknown'. As traffic was visible; and not on intersecting course; reply was made 'traffic in sight; no factor'.soon thereafter; the unknown traffic was observed to change course on a right turn; finishing turn on a direct intersection course with our aircraft; at the same altitude. The incoming aircraft had strobe lights active; so the intersecting course was very clear. Evasive action was taken with a standard rate turn to the right.the incoming aircraft was observed to initiate a left turn; thereby remaining on intersecting course. At this point I increased bank of turn; pulled power and initiated a steep descent. Incoming aircraft was now observed to be on a shallow descent; and very nearly intersecting our course despite evasive actions. It is my judgment that if I had not initiated a steep descent; collision was probable. Estimate that the incoming aircraft passed <500 feet behind; and +/- 200 feet of our altitude. GPS data onboard shows that we descended 300 feet in 15 seconds and altered course by 60deg.incoming aircraft observed as probable to be a twin engine; low wing general aviation type aircraft. Original course and altitude was resumed; and finally ATC was informed that traffic became a factor and evasive actions were taken.contributing factors:both aircraft navigating over a tfr (surface to 5500 feet).due to tfr and recent high winds; minimal GA traffic expected to be operating in the airspaceincoming aircraft was (I understand) not on flight following and not in contact with ATC.

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Original NASA ASRS Text

Title: C172 pilot reported a NMAC with another light aircraft in vicinity of FIM VOR.

Narrative: [I was] on Flight Following with ATC Pt Mugu; [vicinity of FIM]; 6500ft; westbound. [I was] acting as PIC; with another pilot (student) in right seat. Received warning 'traffic at 1 o'clock; 6500 feet; heading northeast; type unknown'. As traffic was visible; and not on intersecting course; reply was made 'Traffic in sight; no factor'.Soon thereafter; the unknown traffic was observed to change course on a right turn; finishing turn on a direct intersection course with our aircraft; at the same altitude. The incoming aircraft had strobe lights active; so the intersecting course was very clear. Evasive action was taken with a standard rate turn to the right.The incoming aircraft was observed to initiate a left turn; thereby remaining on intersecting course. At this point I increased bank of turn; pulled power and initiated a steep descent. Incoming aircraft was now observed to be on a shallow descent; and very nearly intersecting our course despite evasive actions. It is my judgment that if I had not initiated a steep descent; collision was probable. Estimate that the incoming aircraft passed <500 feet behind; and +/- 200 feet of our altitude. GPS data onboard shows that we descended 300 feet in 15 seconds and altered course by 60deg.Incoming aircraft observed as probable to be a twin engine; low wing General Aviation type aircraft. Original course and altitude was resumed; and finally ATC was informed that traffic became a factor and evasive actions were taken.Contributing Factors:Both aircraft navigating over a TFR (Surface to 5500 feet).Due to TFR and recent high winds; minimal GA traffic expected to be operating in the airspaceIncoming aircraft was (I understand) not on Flight Following and not in contact with ATC.

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.