Narrative:

Pilot's aircraft was on initial test flight, remaining in airport traffic pattern. This aircraft has no electrical system and no radio. Traffic pattern had several aircraft in the blm traffic pattern. My aircraft merged with the existing traffic and entered downwind. I noticed 1 red/white small aircraft X ahead of me and 1 red/white small aircraft Y behind me in the traffic pattern. In order to remain safely within the runway environment on this initial test flight, I slowed my aircraft and elected not to extend my downwind out as far as many of the other aircraft in the pattern. Since my experimental aircraft has a high sink rate, I was still at 1000 ft AGL on base. I maneuvered to keep spacing from the red/white small aircraft X ahead of me and did not notice that a student pilot in another red/white small aircraft Z had not seen me and turned base under me. As I scanned the airport traffic pattern, I noticed that the red/white small aircraft X had cleared the active, and I still had a red/white small aircraft Y behind me. (There were 3, not 2 like aircraft in the pattern!) to allow for my high sink rate, I stayed high on final and, unknown to me, passed directly over the red/white small aircraft Z that cut into the sequence. This student pilot initiated a go around, without further incident. Observers on the ground watching my flight saw the small aircraft Z initiate a go around, however, no one thought that we passed dangerously close. The figures I used for the estimated miss were provided by the student pilot's estimate. To restate, I had full view of the runway environment on final and never saw this aircraft. The small aircraft Z being a high wing, limited his upward visibility and my mid-wing limits my downward visibility. 1 contributing factor could be the size of the traffic pattern. Many aircraft extend downwind for spacing, instead of simply slowing their aircraft to a speed that allows safe separation. Now seeing the flight characteristics and visibility characteristics of my experimental aircraft, I will modify my procedures to ensure maximum safe operation.

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Original NASA ASRS Text

Title: AN EXPERIMENTAL SMA ON ITS FIRST FLT CAUSED AN SPI IN AN SMA TO GAR AT AN UNCTLED ARPT.

Narrative: PLT'S ACFT WAS ON INITIAL TEST FLT, REMAINING IN ARPT TFC PATTERN. THIS ACFT HAS NO ELECTRICAL SYS AND NO RADIO. TFC PATTERN HAD SEVERAL ACFT IN THE BLM TFC PATTERN. MY ACFT MERGED WITH THE EXISTING TFC AND ENTERED DOWNWIND. I NOTICED 1 RED/WHITE SMA X AHEAD OF ME AND 1 RED/WHITE SMA Y BEHIND ME IN THE TFC PATTERN. IN ORDER TO REMAIN SAFELY WITHIN THE RWY ENVIRONMENT ON THIS INITIAL TEST FLT, I SLOWED MY ACFT AND ELECTED NOT TO EXTEND MY DOWNWIND OUT AS FAR AS MANY OF THE OTHER ACFT IN THE PATTERN. SINCE MY EXPERIMENTAL ACFT HAS A HIGH SINK RATE, I WAS STILL AT 1000 FT AGL ON BASE. I MANEUVERED TO KEEP SPACING FROM THE RED/WHITE SMA X AHEAD OF ME AND DID NOT NOTICE THAT A STUDENT PLT IN ANOTHER RED/WHITE SMA Z HAD NOT SEEN ME AND TURNED BASE UNDER ME. AS I SCANNED THE ARPT TFC PATTERN, I NOTICED THAT THE RED/WHITE SMA X HAD CLRED THE ACTIVE, AND I STILL HAD A RED/WHITE SMA Y BEHIND ME. (THERE WERE 3, NOT 2 LIKE ACFT IN THE PATTERN!) TO ALLOW FOR MY HIGH SINK RATE, I STAYED HIGH ON FINAL AND, UNKNOWN TO ME, PASSED DIRECTLY OVER THE RED/WHITE SMA Z THAT CUT INTO THE SEQUENCE. THIS STUDENT PLT INITIATED A GAR, WITHOUT FURTHER INCIDENT. OBSERVERS ON THE GND WATCHING MY FLT SAW THE SMA Z INITIATE A GAR, HOWEVER, NO ONE THOUGHT THAT WE PASSED DANGEROUSLY CLOSE. THE FIGURES I USED FOR THE ESTIMATED MISS WERE PROVIDED BY THE STUDENT PLT'S ESTIMATE. TO RESTATE, I HAD FULL VIEW OF THE RWY ENVIRONMENT ON FINAL AND NEVER SAW THIS ACFT. THE SMA Z BEING A HIGH WING, LIMITED HIS UPWARD VISIBILITY AND MY MID-WING LIMITS MY DOWNWARD VISIBILITY. 1 CONTRIBUTING FACTOR COULD BE THE SIZE OF THE TFC PATTERN. MANY ACFT EXTEND DOWNWIND FOR SPACING, INSTEAD OF SIMPLY SLOWING THEIR ACFT TO A SPD THAT ALLOWS SAFE SEPARATION. NOW SEEING THE FLT CHARACTERISTICS AND VISIBILITY CHARACTERISTICS OF MY EXPERIMENTAL ACFT, I WILL MODIFY MY PROCS TO ENSURE MAX SAFE OP.

Data retrieved from NASA's ASRS site as of July 2007 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.