Fragmented Sections Of The Outboard Left Wings Of Both Airplanes Were Found In A Field

Location: Longmont, CO Accident Number: CEN22FA424
Date & Time: September 17, 2022, 08:53 Local Registration: N2117Y (A1); N255BF (A2)
Aircraft: Cessna 172S (A1); Sonex Aircraft Xenos (A2) Injuries: 2 Fatal (A1); 1 Fatal (A2)
Flight Conducted Under: Part 91: General aviation – Instructional (A1); Part 91: General aviation – Personal (A2)

On September 17, 2022, about 0853 mountain daylight time, a Cessna 172S, N2117Y, and a Sonex Aircraft Xenos, N255BF, were destroyed when they were involved in a mid-air collision near Longmont, Colorado. The flight instructor and student pilot aboard the Cessna and the pilot aboard the Sonex sustained fatal injuries. The Cessna was operated as Title 14 Code of Federal Regulations Part 91 instructional flight. The Sonex was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

A review of air traffic control (ATC) flight track data revealed the Cessna departed Rocky Mountain Municipal Airport (BJC), Denver, Colorado, about 0843, and the Sonex departed Platte Valley Airpark (18V), Hudson, Colorado, about 0838. The airplanes climbed to about 7,000-7,500 ft mean sea level (msl) and were operating under visual flight rules (VFR). The Cessna flew northbound and the Sonex flew westbound toward the Longmont area. After the Cessna completed a left 360° turn, it turned eastbound. The flight track data of the two airplanes merged and subsequently showed both airplanes rapidly descending. Fragmented sections of the outboard left wings of both airplanes were found in a field below the point where the two flight tracks merged.

Both airplanes impacted nose down in a rural area with a ground elevation of about 5,100 ft msl. The main wreckage site of the Cessna was in a field about 1,800 ft southeast of the wing fragments. The main wreckage site of the Sonex was adjacent to a tree about 1,100 ft southwest of the wing fragments.

At the time of the accident, both airplanes transmitted a transponder code of 1200 (VFR) and neither airplane was in radio contact, nor was required to be in contact with ATC. Both airplanes operated within the Mode-C veil of the Denver International Airport Class B airspace that required automatic dependent surveillance broadcast (ADS-B) “out” transmissions. The Cessna was equipped with ADS-B “in/out” equipment and transmitted ADS-B data during the accident flight. The Sonex did not transmit ADS-B data during the accident flight; ATC records indicated the Sonex last transmitted ADS-B data on July 14, 2022.

Both airplanes were retained for further examination.