A Cessna Citation landed at LPR 10 to 15 min. prior to the MU-2's approach. The Citation crew reported they flew the ILS Runway 07 approach, then circled to Runway 25. The pilot said they entered the clouds at 3,000 ft. on the descent and received radar vectors for the approach. Visibility was good above the clouds and there was no turbulence in the clouds.

The Citation pilots leveled off at the MDA and flew the right-hand circling pattern at 1,300 to 1,350 ft. MSL (about 500 to 550 ft. AGL). He said they had 3 mi. visibility and remained clear of clouds during the circle-to-land maneuver. The airplane's anti-icing and deicing equipment were on during the approach. He observed about one-eighth inch of ice on the nose of the airplane when they pulled it into the hangar. He reported that the airplane was in the clouds for about 2 to 2.5 min. The weather was essentially as forecast.

The MU-2 pilot held an ATP certificate for single-engine and multiengine land airplanes, and helicopters. He was a certified flight instructor with single-engine airplane, multi-engine airplane and helicopter ratings; and he was an instrument instructor in airplanes and helicopters. The pilot's latest first-class medical certificate had been issued on Nov. 29, 2007. He had accumulated over 2,000 flight hours, 1,285 of which were in multiengine aircraft with 1,250 hr. in the MU-2. He had 231 hr. in helicopters. He recorded 290 hr. of flight in actual instrument conditions and had flown 180 hr. in the MU-2 within the preceding 12 months, and had flown 30 hr. of instrument flying within the preceding 12 months.

The pilot's training records — obtained from the SimCom Training Center — indicated that he obtained initial MU-2 simulator training in October 2002. He returned to SimCom for recurrent MU-2 simulator training on a yearly basis. On Jan. 28, 2009, the pilot attended the SimCom Training Center and received a certificate signifying that he had satisfactorily completed a Special Federal Aviation Regulation (SFAR) 108 compliant MU-2 Recurrent course for the MU-2B-60 model. The pilot was scheduled to return to SimCom for recurrent MU-2 simulator training on Jan. 25-27, 2010.

The owner of the airplane told investigators the pilot was competent and qualified to fly the MU-2 single pilot. He and the accident pilot routinely flew together, and they would switch pilot and copilot responsibilities. They routinely flew in instrument conditions and had often flown IFR approaches in actual instrument conditions. He stated that the accident pilot was a good instrument pilot and that there were no issues with his flying or his technique. The pilot had worked for the owner of the airplane for about 13 years.

The owner reported that neither he nor the accident pilot used the autopilot while flying instrument approaches for landing. He stated that typically, during the approach, the flaps were set to 5 deg. at 175 kt. and then to 20 deg. at 155 kt. He stated that the approach is normally flown at 150 kt. with 20 deg. of flaps. At the bottom of the approach the airplane would be slowed to 115 kt., then the flaps would be moved to 40 deg. The owner reported that he had never seen the accident pilot use 5 deg. of flaps below 500 ft. in visual flight conditions. He stated that the accident pilot always used 20 deg. of flaps from the initial approach point (IAP) to the missed approach point (MAP). The owner stated that it was a “mystery” to him why the flaps had been set at 5 deg. during the accident approach.

The pilot-rated passenger, employed by the owner to maintain the accident airplane and a helicopter, held an A&P rating and a private pilot certificate with a single-engine land rating. During his third-class medical examination on Oct. 10, 2008, the pilot reported that his total flight time was 190 hr. The airplane owner reported that the pilot-rated passenger was not performing the duties of copilot during the flight.