GA pilot reported a near midair collision during final approach to onm airport.

Attributes
ACN	1606463
Time
Date	201812
Local Time Of Day	1201-1800
Place
Locale Reference	OMN.Airport
State Reference	FL
Environment
Flight Conditions	VMC
Aircraft 1
Make Model Name	Small Aircraft
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	Visual Approach
Flight Plan	None
Aircraft 2
Make Model Name	Small Aircraft
Flight Phase	Cruise
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Flight Engineer Flight Crew Flight Instructor Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 250 Flight Crew Total 38000 Flight Crew Type 400
Events
Anomaly	ATC Issue All Types Conflict NMAC
Miss Distance	Horizontal 0 Vertical 100

Narrative:

I reported to tower 5 miles north; inbound to land. The tower instructed me to report mid-field downwind; 'your choice right or left downwind.' I said I would report right downwind. I heard no other traffic on the frequency. Just as I was approaching mid-field downwind and about to report downwind; a small aircraft flying opposite direction flew directly overhead; approximately 100 feet above me. At that point the controller cleared me to land. The controller then told the other aircraft; 'sorry about that.' I spoke with the other pilot afterwards; he said he was breaking in an engine and flying orbits near the airport as cleared by the controller. As far as I know; we were the only aircraft in the class D airspace at the time. The other aircraft was close enough that I could hear his engine as he passed overhead.

Original NASA ASRS Text

Title: GA pilot reported a NMAC during final approach to ONM airport.

Narrative: I reported to Tower 5 miles north; inbound to land. The Tower instructed me to report mid-field downwind; 'your choice right or left downwind.' I said I would report right downwind. I heard no other traffic on the frequency. Just as I was approaching mid-field downwind and about to report downwind; a small aircraft flying opposite direction flew directly overhead; approximately 100 feet above me. At that point the controller cleared me to land. The controller then told the other aircraft; 'sorry about that.' I spoke with the other pilot afterwards; he said he was breaking in an engine and flying orbits near the airport as cleared by the controller. As far as I know; we were the only aircraft in the Class D airspace at the time. The other aircraft was close enough that I could hear his engine as he passed overhead.

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.