CEN19LA107

As the pilot approached the airport, another pilot heard him on the radio and advised him of "significant down drafts" on the approach to runway 15. The pilot acknowledged the transmission and continued his approach. When he turned onto the base leg, he encountered the "severe down-draft/microburst" the other pilot had mentioned. He applied full power in an attempt to climb out, but the airplane continued to descend striking a power-line and tree, and subsequently impacted terrain. A review of the weather showed that a complex wind pattern existed over the area during the period with a wind shift occurring immediately after the time of the accident. No support for convective microburst activity was noted over the area; however, a large area of light intensity precipitation with some potential for some outflow was noted, which could have been resulted in the different winds occurring over the accident site during the period. In addition, the High Resolution Rapid Refresh model sounding and satellite imagery and pilot reports noted support for mountain wave activity over the area, which supported downslope winds and downdraft activity in the area at the time of the accident. The National Weather Service had AIRMET advisories for turbulence and IFR and mountain obscuration conditions over the area, but no advisory for low-level wind shear. It is likely the pilot encountered shifting winds due to weather system in the area. With his reduced engine power on the base leg of the traffic pattern, the pilot most likely got into a downdraft that produced a sink rate that he could not recover from.

On March 23, 2019, at 1043 mountain daylight time, a Cessna R172E, N7879N, was destroyed when it struck a power line and impacted a dairy farm 1.5 miles northwest of runway 15 at Northern Colorado Regional Airport (FNL), Loveland, Colorado. The pilot was seriously injured and his two passengers sustained minor injuries. The airplane was registered to the U.S. Air Force and operated by the Peterson Air Force Base (AFB) Aero Club, Peterson AFB, Colorado, under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91. Visual meteorological conditions prevailed at the time of the accident, and no flight plan had been filed for the personal cross-country flight. The flight originated from the City of Colorado Springs Municipal Airport (COS), and was en route to FNL. The pilot, a 10-year U.S. Army UH-60M Blackhawk helicopter pilot, said he was accumulating fixed-wing civilian flight time and had brought along two passengers. According to the pilot, he and his passengers intended to fly from COS to FNL and return. He said he was weather briefed for the flight and received multiple weather briefings before takeoff. As they approached FNL from the southwest, he made a call on FNL's common traffic advisory frequency (CTAF) and reported he was entering a right traffic pattern for runway 15. Another pilot heard the report and advised him of "significant down drafts" on the approach to runway 15. The pilot acknowledged the transmission and continued his approach. When he turned onto the base leg, he encountered the "severe down-draft/microburst" the other pilot had mentioned. He applied full power in an attempt to climb out, but the airplane struck a power-line and tree, and impacted terrain. At 1056, the automated weather observation station at FNL reported, wind 170° at 11 kts, visibility of 10 miles, light rain, few clouds at 1,600 ft, ceilings 3,800 ft broken, 4,800 ft overcast, temperature 43° F, dew point 36° F, and altimeter setting 29.93 inches of Mercury. A NTSB Meteorologist's review of the weather showed that a complex wind pattern existed over the area during the period with a wind shift occurring immediately after the time of the accident. No support for convective microburst activity was noted over the area; however, a large area of light intensity precipitation with some potential for some outflow was noted, which could have been resulted in the different winds occurring over the accident site during the period. In addition, the High Resolution Rapid Refresh model sounding and satellite imagery and pilot reports noted support for mountain wave activity over the area, which supported downslope winds and downdraft activity in the area at the time of the accident. The National Weather Service had AIRMET advisories for turbulence and IFR and mountain obscuration conditions over the area, but no advisory for low-level wind shear.