Narrative:

I was in a cruise descent with a nose down attitude heading eastbound to inspect a lake surface for a possible landing site and when I leveled the plane I saw another aircraft about 100-200 feet above me and to my left that had been hidden by either the ceiling or bulkhead of my aircraft. As soon as I saw the aircraft I took action by descending and banking right away from the other aircraft. The other aircraft took action as well by climbing and banking right. I did have the sun at my back and I can only assume the other pilot did not see my beacon or landing light against the glare of the sun. I can only guess as to why I didn't see the other aircraft before beginning my descent. The setting sun was causing reflections off of other objects that may have distracted me from seeing the beacon of the other aircraft. Even though I didn't feel like I spent more than 20 seconds looking at the lake directly I accept that my perception of it might have been skewed and more time had elapsed than I was aware of. I do think that this has reinforced the importance of scanning for traffic even during a descent to a landing. In future I will be more diligent in scanning under the wings as well as behind the bulkheads especially during a descent into a pattern around an uncontrolled lake. While I do not believe that we got within 500 feet of each other the events happened so quickly that I cannot be absolutely sure that we did not.

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Original NASA ASRS Text

Title: GA pilot reported a NMAC with another GA aircraft while surveying a lake for landing suitability.

Narrative: I was in a cruise descent with a nose down attitude heading eastbound to inspect a lake surface for a possible landing site and when I leveled the plane I saw another aircraft about 100-200 feet above me and to my left that had been hidden by either the ceiling or bulkhead of my aircraft. As soon as I saw the aircraft I took action by descending and banking right away from the other aircraft. The other aircraft took action as well by climbing and banking right. I did have the sun at my back and I can only assume the other pilot did not see my beacon or landing light against the glare of the sun. I can only guess as to why I didn't see the other aircraft before beginning my descent. The setting sun was causing reflections off of other objects that may have distracted me from seeing the beacon of the other aircraft. Even though I didn't feel like I spent more than 20 seconds looking at the lake directly I accept that my perception of it might have been skewed and more time had elapsed than I was aware of. I do think that this has reinforced the importance of scanning for traffic even during a descent to a landing. In future I will be more diligent in scanning under the wings as well as behind the bulkheads especially during a descent into a pattern around an uncontrolled lake. While I do not believe that we got within 500 feet of each other the events happened so quickly that I cannot be absolutely sure that we did not.

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.