On April 6, 1999, approximately 1145 mountain daylight time, an Aviat A-1 Husky airplane, N345HU, departed its home base of Boise, Idaho, for Emmett, Idaho, on a 14 CFR 91 personal flight. No flight plan was filed for the flight. The airplane subsequently crashed in hilly terrain approximately 3 miles south-southeast of the Emmett airport. The airplane was substantially damaged and its private pilot/owner and a pilot-rated passenger, occupying the rear seat (which had had its control stick removed), were seriously injured. The Gem County, Idaho, sheriff was notified of the accident when the passenger called for aid from the accident site via cellular telephone at 1514. Visual meteorological conditions were reported at Caldwell, Idaho, during the time frame of the accident flight. As the aircraft departed Boise's airspace, Boise Departure Control terminated radar service and approved a frequency change. However, following termination of radar service to the accident aircraft, the Boise approach control radar continued to track the aircraft into the vicinity of the accident. For approximately the last minute of radar contact, from 1223:32 to 1224:28, the aircraft was recorded on a generally straight westerly track, descending from 3,300 feet at 1223:32 to the last recorded radar position, 15.7 miles west and 11.1 miles north of the radar antenna (referenced to magnetic), at 3,100 feet, at 1224:28. Terrain in the vicinity of the last recorded radar position varies from approximately 2,800 to 3,100 feet above sea level. The crash site elevation was approximately 2,800 feet. In interviews conducted by an FAA investigator, both aircraft occupants reported that while the aircraft was flying at low altitude in the accident area, one of the occupants (the pilot reported it was the passenger) spotted a coyote. The pilot reported the aircraft's altitude as about 500 to 600 feet, with the passenger reporting that terrain was above the aircraft on both sides and that the aircraft was low enough to enable him to see colored ear tags on cattle below. The pilot reported that upon coming out of a 270-degree left turn intended to position the aircraft to view the coyote, the aircraft had a rate of descent "greater than he had ever experienced", and that adding power and pulling back on the stick failed to arrest the descent. According to the FAA investigator's record, the pilot "said at the last second he was pointed down, to prevent crashing on the nose he pull[ed] full aft on the stick, the nose came up and the aircraft impacted the ground." The FAA investigator reported that the pilot could not recall his airspeed and altitude at the initiation of the 270-degree turn, although both the low-altitude cruising flight and the turn were performed with 10 degrees of flaps. On his NTSB accident report, the pilot indicated that no mechanical failure or malfunction was involved in the accident. The passenger stated that when the coyote was spotted, one of the occupants (the passenger could not remember which one) shouted that he had spotted the coyote. The passenger stated that the airplane then immediately rolled into a steep left turn, and that the next thing he remembered was ground impact. Both occupants stated to the FAA investigator that the airplane did not lose engine power during the accident sequence. No witnesses to the accident were identified. However, the owner of the property where the accident occurred reported to an FAA investigator that he had seen the accident aircraft in that area on previous occasions, flying low. The property owner reported that he had last seen the accident aircraft in that area two days before the accident. An FAA investigator responded to the accident site and performed an on-site examination of the aircraft wreckage. The FAA investigator reported to the NTSB that he found no evidence of aircraft or engine malfunctions in his on-site examination, and also reported that he found 20 gallons of fuel in the aircraft's wing tanks. Winds at Caldwell, Idaho, 14 nautical miles south-southwest of the accident site, were reported as being from 360 degrees at 4 knots at 1235. The highest winds reported at either Boise or Caldwell between the time of the last radar contact and the time of the passenger's cell phone call to the Gem County sheriff were 9 knots, reported at Caldwell at 1255. Data furnished by the Boise Automated Flight Service Station (AFSS) did not indicate that any AIRMET advisories for turbulence were in effect during the time frame of the accident flight.