Narrative:

I was giving two orientation rides. We landed at thv to switch front and back seat passengers. We did the routine pre-flight checks and prepared to enter runway 17 for takeoff. From the time I started the engine to the time we entered the runway (estimated about 5 minutes) the only transmission we heard on the radio was from one aircraft who announced she was 7 miles north of the field and planned to land at thv. Before entering the runway I looked to my left for landing traffic and didn't see anyone. On the unicom frequency I announced our intention to enter the active runway 17 for takeoff and then proceeded to enter the runway and accelerate for takeoff. Before reaching the displaced threshold I glanced up and was surprised to see a v-tailed bonanza passing over me at an altitude of about 50 ft. I immediately pulled the power back to idle and applied brakes because I wasn't sure if the pilot was going around or landing in front of me; and I didn't want to run into him on the ground if he was landing. At the same time someone on the ground (possibly another aircraft that was in back of us in the parking area) announced 'bonanza there is a cessna below you;' but there was no response from the bonanza. As it turned out he did a go-around and we continued to the next taxiway exit; and then returned to the end of the runway for an uneventful takeoff. The bonanza continued around the pattern and made an uneventful landing. At no time did we hear any radio transmissions from the bonanza. If I saw the bonanza on final I definitely would have waited before entering the active runway; so I have been thinking about why I didn't see the airplane. It's possible that because I didn't hear any traffic on the radio; I didn't expect to see anything when I looked for traffic on final; so I might have looked but didn't really see. It's possible that with the high cirrus overcast I might not have been able to see the light colored aircraft on final unless its landing light was on. I can only assume it wasn't on; otherwise I believe that I would have spotted it if it was in my field of view. There is also a chance that it was impossible for me to spot the aircraft on final; depending on its position. At the point we were stopped before entering the runway we were approximately 200 ft from a 15-foot tall blast fence at the end of the runway. I estimate that my eyes were approximately 6 ft off the ground so this gives a line of sight of about 2.6 degrees to the top of the fence. The PAPI light system has a slope of 4.5 degrees and the AFD says the approach path is 16:1 or 3.6 degrees. If the bonanza was 3;000 ft from the threshold when we entered the runway; and 100 ft or so low then the blast fence would have blocked it from view. I guess I'll never know the real reason; and I'm fortunate that everything did turn out ok. I like to think that I'm extra vigilant when I'm flying a parent's pride and joy but this shows that you can never be too careful.

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Original NASA ASRS Text

Title: A pilot departing THV; after making a departure announcement on CTAF; rejected his takeoff as a Bonanza passed him overhead without having acknowledged the reporter's prior CTAF traffic announcements.

Narrative: I was giving two orientation rides. We landed at THV to switch front and back seat passengers. We did the routine pre-flight checks and prepared to enter Runway 17 for takeoff. From the time I started the engine to the time we entered the runway (estimated about 5 minutes) the only transmission we heard on the radio was from one aircraft who announced she was 7 miles north of the field and planned to land at THV. Before entering the runway I looked to my left for landing traffic and didn't see anyone. On the UNICOM frequency I announced our intention to enter the active Runway 17 for takeoff and then proceeded to enter the runway and accelerate for takeoff. Before reaching the displaced threshold I glanced up and was surprised to see a V-tailed Bonanza passing over me at an altitude of about 50 FT. I immediately pulled the power back to idle and applied brakes because I wasn't sure if the pilot was going around or landing in front of me; and I didn't want to run into him on the ground if he was landing. At the same time someone on the ground (possibly another aircraft that was in back of us in the parking area) announced 'Bonanza there is a Cessna below you;' but there was no response from the Bonanza. As it turned out he did a go-around and we continued to the next taxiway exit; and then returned to the end of the runway for an uneventful takeoff. The Bonanza continued around the pattern and made an uneventful landing. At no time did we hear any radio transmissions from the Bonanza. If I saw the Bonanza on final I definitely would have waited before entering the active runway; so I have been thinking about why I didn't see the airplane. It's possible that because I didn't hear any traffic on the radio; I didn't expect to see anything when I looked for traffic on final; so I might have looked but didn't really see. It's possible that with the high cirrus overcast I might not have been able to see the light colored aircraft on final unless its landing light was on. I can only assume it wasn't on; otherwise I believe that I would have spotted it if it was in my field of view. There is also a chance that it was impossible for me to spot the aircraft on final; depending on its position. At the point we were stopped before entering the runway we were approximately 200 FT from a 15-foot tall blast fence at the end of the runway. I estimate that my eyes were approximately 6 FT off the ground so this gives a line of sight of about 2.6 degrees to the top of the fence. The PAPI light system has a slope of 4.5 degrees and the AFD says the approach path is 16:1 or 3.6 degrees. If the Bonanza was 3;000 FT from the threshold when we entered the runway; and 100 FT or so low then the blast fence would have blocked it from view. I guess I'll never know the real reason; and I'm fortunate that everything did turn out OK. I like to think that I'm extra vigilant when I'm flying a parent's pride and joy but this shows that you can never be too careful.

Data retrieved from NASA's ASRS site as of July 2013 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.