On June 16, 1996, approximately 1610 hours Pacific daylight time, a Cessna 177B, N1159C, registered to and being flown by a private pilot, was substantially damaged when the aircraft collided with a tree after undershooting the final approach to runway 28 at the Diamond Point airstrip, Gardiner, Washington. The pilot and two of the three passengers sustained minor injuries. A third passenger was seriously injured. Visual meteorological conditions existed and no flight plan had been filed. The flight, which was personal, was to have been operated under 14CFR91, and originated from Eastsound, Washington, approximately 1530. The pilot reported that on final approach to runway 28 he encountered a downdraft and collided with a fir tree more than 400 feet short of the threshold. The aircraft then descended impacting and coming to rest against a mobile home a little over 300 feet short of the threshold and on the runway extended centerline. The 1555 local surface winds reported at Port Angeles, located 23 nautical west southwest of the accident site, were 250 degrees magnetic at 10 knots gusting to 15 knots.