Aerobatic pilot reported a near midair collision in the pattern at sna airport.

Attributes
ACN	1413877
Time
Date	201612
Place
Locale Reference	SNA.Airport
State Reference	CA
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Aerobatic
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	None
Aircraft 2
Make Model Name	Cessna Aircraft Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Person 1
Function	Pilot Flying
Qualification	Flight Crew Flight Instructor Flight Crew Commercial Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 16 Flight Crew Total 5000 Flight Crew Type 1500
Events
Anomaly	Conflict NMAC
Miss Distance	Vertical 500

Narrative:

I was practicing landings in a moderately busy pattern. At the time of the incident I was [planned] to land #2 behind a high wing cessna. As he was preparing to turn base; I was instructed by the tower to 'change to runway 20R' and was cleared for the option. At that time I turned from downwind to base entry for 20R. The #1 airplane for 20L was in his base turn in a descent. I felt it safe and appropriate to overfly on an extended base to 20R. Vertical separation was very adequate in my estimation. I had the traffic in sight at the time. Apparently from his vantage point I was too close. I [admit] no guilt but acknowledge in retrospect I should have extended my downwind a bit before commencing left turn. As he was in a high wing airplane; his view was probably limited whereas my view from above [allowed me] to safely avoid as necessary.

Original NASA ASRS Text

Title: Aerobatic pilot reported a NMAC in the pattern at SNA airport.

Narrative: I was practicing landings in a moderately busy pattern. At the time of the incident I was [planned] to land #2 behind a high wing Cessna. As he was preparing to turn base; I was instructed by the tower to 'Change to runway 20R' and was cleared for the option. At that time I turned from downwind to base entry for 20R. The #1 airplane for 20L was in his base turn in a descent. I felt it safe and appropriate to overfly on an extended base to 20R. Vertical separation was very adequate in my estimation. I had the traffic in sight at the time. Apparently from his vantage point I was too close. I [admit] no guilt but acknowledge in retrospect I should have extended my downwind a bit before commencing left turn. As he was in a high wing airplane; his view was probably limited whereas my view from above [allowed me] to safely avoid as necessary.

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.