Any Unknown or Unlisted Aircraft Manufacturer
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 7.0
Situational Awareness; Workload
Conflict NMAC; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Air Traffic Control Issued Advisory / Alert; Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Flight Crew Became Reoriented; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Took Evasive Action; Flight Crew Requested ATC Assistance / Clarification
Aircraft; Airspace Structure; Chart Or Publication; Human Factors; Procedure
The VFR Aircraft; Aircraft X; was cleared on the [published VFR route] to maintain 5;500 feet. He was southbound and converging over the VOR with Aircraft Y who was IFR and descended to 5;000 feet and told about the 5;500 feet traffic that was at the time 4 miles north of the VOR. Everything was fine and it was a normal everyday situation. I was cleaning up some loose ends giving headings to other aircraft and traffic advisories; many traffic advisories. I had an aircraft report getting an RA but its resolution told him to stay where they were because there were just so many VFR's. Then I hear the Traffic Alert start which isn't uncommon for aircraft 500 feet apart in this airspace and as I look up the Aircraft Y tells me he's responding to an RA and his voice is clearly strained.I incorrectly said what I was thinking which was 'Aircraft X what are you doing! Climb immediately to 5;500' as I'm watching him descend through 5;200 feet right on top of Aircraft Y. He responds that he 'thought they were on a collision course'. To which I informed him that his actions caused the collision course. He also turned right which would have been fine if that's all he had done and stayed at 5;500 feet; but the descent made it a near or for sure mid-air if Aircraft Y hadn't taken evasive action. I issued a Brasher Warning to the pilot of Aircraft X because he 100% cause a perfectly separated situation to become a very ugly situation. Both aircraft were in the Class Bravo airspace and the VFR aircraft had no right or reason to descend at all.Over the top of LA is just a busy place where aircraft are routinely separated by 500 feet; that's just life. If they move the VFR areas where Special Flight Rules is to somewhere else then we would definitely have more altitudes to use to separate people by greater than 500 feet. but; until that happens it's just going to be what it's going to be.
While on a Class B clearance through the Class Bravo airspace on published VFR Route southbound at 5;500 feet; I received a traffic notification from Approach for traffic at 11 o'clock; opposite direction; at 5;000 MSL a conflict for traffic that was approaching nearly head-on. I continued to visually scan for the traffic in front of me; and when I finally spotted the oncoming traffic it was at my 11 o'clock to 11:30 position in my windscreen; at eye level. I was unable to discern any relative motion of the target relative to my windscreen. The only change I could see in the target was that it was getting larger in my field of view; and that it appeared to be some type of small jet aircraft. I immediately initiated a turn to my right in order to avoid the oncoming traffic. The turn that I initiated was done very quickly; and was probably on the order of a 30 to 35 degree angle of bank. As a result of this turn; I lost approximately 250 feet of altitude from my cruising altitude of 5;500 feet. My change in heading was approximately 45 degrees; and once my turn was completed I was able to discern relative motion of the target with respect to my windscreen and left side window. The traffic was now moving to my left; and the separation between the two of us was increasing.The opposite directly traffic passed well behind me. At that point the TRACON Controller called me and admonished me for deviating from my assigned heading and altitude. I responded to the controller with an apology; and explained that the opposite direction traffic appeared to be on a collision course with me; and it required me to take evasive action. The controller provided me with a toll-free number to call after I landed. After landing I called the toll-free number and spoke to an individual at SOCAL who asked me to describe the occurrence from my perspective. I described the occurrence in an identical manner to what I have written here. The individual was very courteous and listened carefully to my explanation; and thanked me for calling. The call ended with no indication to me that any further action would be forthcoming.It is extremely difficult to estimate lateral and vertical separation of traffic; especially when a target has no apparent relative motion and is approaching head-on. Any vertical separation that does exist between two aircraft in this situation will not be perceptible until the aircraft are very close together; when there is very little time to take evasive action if it is required. In this particular case; the opposite direction traffic was probably traveling at least twice as fast as my aircraft; resulting in an effective rate of closure of at least 400 MPH. A vertical separation of 500 feet is very small; and when possible sources of altitude error are included; it is possible that the actual vertical separation between our two aircraft was less than 500 feet.  Approximately ten minutes after this occurrence; I was in the vicinity of another airport and was in contact with another sector of the TRACON. This Controller provided me with a traffic advisory regarding jet traffic inbound from the west at 5;000 feet; and gave me instructions to climb and maintain 6;000 feet for separation purposes. I initiated the climb and leveled off at 6;000 feet; and observed the jet traffic passed well below me. After the jet traffic had crossed my flight path; the Controller cleared me back down to 5;500 feet. I have included a description of this action on the part of Approach as an example of prudent traffic management.In summary; I should have been more diligent in maintaining my assigned altitude of 5;500 feet during my turn to avoid the oncoming traffic. However; it was my belief that there was insufficient separation between the flight paths of our two aircraft; and seeing no relative motion of a target that was at eye-level in my windscreen; as pilot-in-command of the aircraft I took evasive action in the interest of collision avoidance.
SCT TRACON Controller and a GA pilot reported evasive action by GA pilot caused an RA for opposite direction traffic.