HISTORY OF FLIGHTOn May 20, 2016, about 1100 mountain daylight time, an experimental amateur-built Michael Burton (AutoGyro GmbH) Calidus, N50NE, collided with mountainous terrain near Fruitland, Utah. The gyroplane was registered to the builder and operated by the pilot under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The private pilot and passenger were seriously injured, and the gyroplane sustained substantial damage. The cross-country personal flight departed Duchesne Municipal Airport, Duchesne, Utah, about 1015, with a planned destination of Spanish Fork Airport-Springville-Woodhouse Field, Spanish Fork, Utah. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot reported that they departed from Glenwood Springs Municipal Airport, Glenwood Springs, Colorado, earlier that morning and stopped at Duchesne for fuel. They then departed west towards Spanish Fork on a route over the Wasatch Mountain Range. As they approached the last ridge, about 200 ft above its peak, they encountered strong downdrafts and the gyroplane descended 500 ft and into a box canyon. Unable to out-climb the terrain, the pilot guided the gyroplane over a river at the base of the canyon until he could see a landing spot on the shore. As he approached the site and initiated the landing flare, the right wheel struck a boulder and the gyroplane rolled over, coming to rest in the river. A witness, who was fishing in the river, called 911 after climbing to a peak where he was able to acquire cell phone reception. Due to the remoteness of the site, the pilot and passenger were not recovered until later in the afternoon. The gyroplane came to rest within a canyon, at an elevation of about 7,300 ft mean sea level. The canyon walls rose about 1,000 ft above the accident site to the north and south. The projected route of flight would have required clearance over rugged 8,200 ft peaks, about 5 miles north of the 9,420 ft summit of Baldy Mountain. About the time of the accident, a weather observation station located at Carbon County Regional Airport/Buck Davis Field, 37 miles south-southeast of the accident site and at an elevation of 5,957 ft, reported wind from 170 degrees at 20 knots gusting 25 knots. About the same time, at Provo Municipal Airport, 38 miles west at an elevation of 4,497 ft, wind was reported from 130 degrees at 15 knots, gusting to 22 knots. The gyroplanes Pilot Operating Handbook specified a maximum demonstrated operating altitude of 10,000 ft. The pilot reported that the gyroplanes maximum gross weight was 1,256 pounds, and the that the weight at the time of the accident was 1,100 pounds. The pilot stated that the gyroplane did not experience any mechanical malfunctions or failures, and that the accident could have been avoided if he had approached the mountain ridge at a higher altitude. The Federal Aviation Administration Bioaeronautical Research Laboratory performed toxicology tests on a sample of blood that was collected from the pilot at 1546 on the day of the accident. Results identified 0.0111 ug/ml of tetrahydrocannabinol carboxylic acid (THC-COOH) in his blood. Tetrahydrocannabinol carboxylic acid (THC-COOH) is the primary metabolite of tetrahydrocannabinol (THC), the main psychoactive compound in marijuana. The report did not document the presence of THC. The reporting cutoff for THC was 0.001 ug/ml.