Narrative:

Late afternoon personal flight; perfect visibility and high clouds; returning to home airport; turning base to final. Several aircraft and gliders nearby and/or in pattern. One east-west paved runway and gliders and tow planes land on grass parallel on south side. Normal pattern is left at 1400ft (1000 AGL).shortly after turning left base to final; at approximately 800ft (400 AGL); I saw a glider just in front; to the right and approximately 100ft below me passing from right to left on a diagonal final to land on the south side grass. Though I took evasive action by briefly arresting my descent; it probably had no effect on the fortunate outcome; and it was by then too late to perform a go around and it was not necessary in order to avoid the other aircraft. Both aircraft then landed normally.I had previously heard a glider announce (unlike many this one had a radio) that it was on a right downwind and later right base in between my own left downwind; base and turn to final calls; but had not seen it until then.in retrospect; I had not thought sufficiently about the implications of a glider making a right pattern to land on the south side while I was making a left pattern to land; in that our paths would inevitably cross; and the glider has the right of way.why did I not see them? The sun was lowish and in the northwest and possibly a factor in not seeing them on right downwind. The glider was lower on final; and perhaps on base below and possibly obscured in the ground clutter of partially forested and rising terrain to the north (i.e.; was likely not silhouetted against the sky). Further; despite my being consciously aware that the glider was on a right pattern; it is very rare for any aircraft; except the occasional helicopter; to fly a right pattern at this airport; so my cognitive set may have influenced my scan pattern; which is normally directed towards searching for left pattern and long final traffic.I do not know why the glider chose a right pattern that one time; and why it did not make all turns to the left as normal/required; but not having an engine; presumably its pilot/instructor had a good reason.next time if I see/hear a glider in a right pattern; I will not descend or turn base until I have positive visual confirmation of the position of the crossing glider. Since most gliders don't have radios; a conscious effort to make a visual lookout for right pattern traffic at any time; but particularly when glider operations are known to be in progress; seems important.

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Original NASA ASRS Text

Title: C172 pilot reported an NMAC with a glider in the pattern at 1N7.

Narrative: Late afternoon personal flight; perfect visibility and high clouds; returning to home airport; turning base to final. Several aircraft and gliders nearby and/or in pattern. One east-west paved runway and gliders and tow planes land on grass parallel on south side. Normal pattern is left at 1400ft (1000 AGL).Shortly after turning left base to final; at approximately 800ft (400 AGL); I saw a glider just in front; to the right and approximately 100ft below me passing from right to left on a diagonal final to land on the south side grass. Though I took evasive action by briefly arresting my descent; it probably had no effect on the fortunate outcome; and it was by then too late to perform a go around and it was not necessary in order to avoid the other aircraft. Both aircraft then landed normally.I had previously heard a glider announce (unlike many this one had a radio) that it was on a right downwind and later right base in between my own left downwind; base and turn to final calls; but had not seen it until then.In retrospect; I had not thought sufficiently about the implications of a glider making a right pattern to land on the south side while I was making a left pattern to land; in that our paths would inevitably cross; and the glider has the right of way.Why did I not see them? The sun was lowish and in the northwest and possibly a factor in not seeing them on right downwind. The glider was lower on final; and perhaps on base below and possibly obscured in the ground clutter of partially forested and rising terrain to the north (i.e.; was likely not silhouetted against the sky). Further; despite my being consciously aware that the glider was on a right pattern; it is very rare for any aircraft; except the occasional helicopter; to fly a right pattern at this airport; so my cognitive set may have influenced my scan pattern; which is normally directed towards searching for left pattern and long final traffic.I do not know why the glider chose a right pattern that one time; and why it did not make all turns to the left as normal/required; but not having an engine; presumably its pilot/instructor had a good reason.Next time if I see/hear a glider in a right pattern; I will not descend or turn base until I have positive visual confirmation of the position of the crossing glider. Since most gliders don't have radios; a conscious effort to make a visual lookout for right pattern traffic at any time; but particularly when glider operations are known to be in progress; seems important.

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.