C182 pilot reported an near midair collision in the pattern at cma airport.

Attributes
ACN	1413905
Time
Date	201701
Local Time Of Day	1201-1800
Place
Locale Reference	CMA.Airport
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Skylane 182/RG Turbo Skylane/RG
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Route In Use	Visual Approach
Flight Plan	VFR
Aircraft 2
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	Initial Approach
Person 1
Function	Single Pilot
Qualification	Flight Crew Multiengine Flight Crew Instrument Flight Crew Flight Instructor Flight Crew Air Transport Pilot (ATP)
Experience	Flight Crew Last 90 Days 15 Flight Crew Total 20000 Flight Crew Type 450
Events
Anomaly	Conflict NMAC
Miss Distance	Vertical 300

Narrative:

I reported to camarillo tower 5 miles west of saticoy bridge. I was cleared to enter a right downwind for runway 26 and tower reported traffic on a right crosswind to a right downwind. I did not have the traffic in sight. Soon after; I was cleared to land runway 26. I continued my descent to traffic pattern altitude for a 45 degree entry for a right downwind. As I began my turn to downwind I suddenly saw the traffic to my right and at my altitude on a converging course. To avoid the conflict I dove from about 1000 to 600 ft as the traffic passed directly over me. There was no indication that the other aircraft saw me.on the ground I notified tower and called the supervisor. He said the other airplane reported that he had me in sight but apparently failed to take corrective action.

Original NASA ASRS Text

Title: C182 pilot reported an NMAC in the pattern at CMA airport.

Narrative: I reported to Camarillo Tower 5 miles west of Saticoy Bridge. I was cleared to enter a right downwind for runway 26 and tower reported traffic on a right crosswind to a right downwind. I did not have the traffic in sight. Soon after; I was cleared to land runway 26. I continued my descent to traffic pattern altitude for a 45 degree entry for a right downwind. As I began my turn to downwind I suddenly saw the traffic to my right and at my altitude on a converging course. To avoid the conflict I dove from about 1000 to 600 ft as the traffic passed directly over me. There was no indication that the other aircraft saw me.On the ground I notified tower and called the supervisor. He said the other airplane reported that he had me in sight but apparently failed to take corrective action.

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.