Narrative:

A jet passed approximately 200 feet below my aircraft when I turned from left base to final in the traffic pattern at jyo. I had entered the pattern on the upwind and announced my position on CTAF throughout the pattern. The jet announced that he was on a straight-in approach at 10 miles and 5 miles out; and then ATC contacted him on jyo CTAF to ask him to switch back to his assigned squawk code until he landed. I do not recall hearing another call on his position until he asked why I had turned final when he was on final. Once I saw him underneath me; I executed a go-around and turned to the right of the runway at approximately 400 ft AGL.root cause: I was not familiar with the jet's airspeed; and did not see him on his non-standard; straight-in final approach as I turned from my standard; left pattern; base to final. I was expecting him to still be at least 2 miles away based on the last position call I received; and my incorrect anticipation of a lower airspeed from his aircraft. At the same time; the jet pilot assumed that I knew how fast he was going to get there; and because he was on the ILS for runway 17; that the other pilots in the pattern would make room for him landing. Neither one of us coordinated with the other aircraft to deconflict until he passed underneath me. From my side; there was no coordination because I thought he was no factor; and he would land after I did.corrective actions: coordinate between pilots directly; rather than making position calls and assuming the other pilot heard the transmission and is going to do what you expect them to.

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Original NASA ASRS Text

Title: GA pilot reported a near miss on final to runway 17 at JYO with a turbojet aircraft.

Narrative: A jet passed approximately 200 feet below my aircraft when I turned from left base to final in the traffic pattern at JYO. I had entered the pattern on the upwind and announced my position on CTAF throughout the pattern. The jet announced that he was on a straight-in approach at 10 miles and 5 miles out; and then ATC contacted him on JYO CTAF to ask him to switch back to his assigned squawk code until he landed. I do not recall hearing another call on his position until he asked why I had turned final when he was on final. Once I saw him underneath me; I executed a go-around and turned to the right of the runway at approximately 400 ft AGL.Root Cause: I was not familiar with the jet's airspeed; and did not see him on his non-standard; straight-in final approach as I turned from my standard; left pattern; base to final. I was expecting him to still be at least 2 miles away based on the last position call I received; and my incorrect anticipation of a lower airspeed from his aircraft. At the same time; the jet pilot assumed that I knew how fast he was going to get there; and because he was on the ILS for runway 17; that the other pilots in the pattern would make room for him landing. Neither one of us coordinated with the other aircraft to deconflict until he passed underneath me. From my side; there was no coordination because I thought he was no factor; and he would land after I did.Corrective Actions: Coordinate between pilots directly; rather than making position calls and assuming the other pilot heard the transmission and is going to do what you expect them to.

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.