On June 3, 2015, about 0700 mountain daylight time, a 1940 year model Waco UPF-7 airplane, N29943, registered to a private LLC, sustained substantial damage following a forced landing resulting from a downdraft while maneuvering over mountainous terrain near Cerro Summit, Colorado. The commercial pilot, who was the sole occupant, sustained serious injuries. The personal flight was being conducted under the provisions of Federal Code of Regulations Part 91. Visual meteorological conditions prevailed throughout the area and no flight plan was filed. The flight originated from the Montrose Regional Airport (MTJ) at 0640 and was en route to its intended destination to Kelly Air Park (CO15), Elbert, Colorado, when the accident occurred. The pilot reported that the surface winds at MTJ (elevation 5,758 feet MSL) were from 140 degrees at 15 knots at the time of takeoff. He circled south of MTJ to gain altitude and elected to depart towards North Pass via Cerro Summit (approx. 8,100 feet MSL). About 5 miles west of Cerro Summit, the airplane had reached about 8,400 feet MSL and the pilot thought that his altitude was sufficient to cross the pass and continued to climb while flying to North Pass. About 2 miles from the pass, a strong downdraft was encountered. The airplane's rate of climb was not sufficient to overcome the downdraft and there was insufficient width of the valley just west of Cerro Summit to complete a turn to lower ground. The pilot stated that he believed that the left wing stalled and the airplane descended about 50 feet before striking the terrain. The pilot stated that during the impact, the engine and engine mount separated and the firewall and front section of the cockpit crushed. Both wings were destroyed and the rear cockpit and empennage remained intact. The Waco UPF-7 has a front/rear pilot seat configuration. The pilot was seated in the rear seat. In NTSB Form 6120, the pilot offered a safety recommendation that it would have been better judgment to have delayed approaching the high terrain of Cerro Summit until he had climbed more than 1,000 feet above the elevation of the pass. Additionally, with surface winds reported at his departure airport (MTJ) were from 140 degrees at 15 knots. Winds aloft at 9,000 feet in the vicinity of the mountain pass were the accident occurred were likely much stronger. Therefore, maintaining an altitude of 2,000 feet or more above the pass's highest terrain would have effected a safer crossing.