CESSNA 172S — Longmont, CO

What happened

Radar track data depicted the accident airplanes on gradually converging flight paths prior to the accident. Immediately before the collision, the Cessna 172 appeared to be on a north-northeast course in level flight at 7,200 feet mean sea level (msl), and the Cessna 180 was in a gradual climb from 6,800 feet msl to 7,000 feet msl on a north course. Day visual meteorological conditions prevailed at the time of the accident, with reported visibilities at 60 miles. Neither pilot was receiving air traffic control advisories at the time of the collision. The radar track associated with the Cessna 180 indicated that after the collision the airplane entered a 270-degree right turn before proceeding to the west. The Cessna 172 continued northbound, as it entered a descent and impacted the ground.

The pilot of the Cessna 180 airplane stated that she heard a loud bang during cruise flight and the airplane immediately pitched up and rolled into right bank. She subsequently determined that elevator control was limited. The pilot attempted to divert to a local airport, but was unable to land on a runway due to the impaired airplane control. She executed a forced landing to an open area adjacent to the airport. A witness reported that the right horizontal stabilizer of the Cessna 180 appeared to be bent down about 90 degrees at mid-span as the airplane approached for the forced landing. The outboard portion of the right horizontal stabilizer of the Cessna 180 airplane was structurally compromised, which resulted in a nearly complete loss of pitch control. The pilot of the Cessna 180 airplane retained marginal pitch control by varying engine power during the remainder of the flight.

A postaccident examination did not reveal any pre-collision failures or malfunctions associated with either airplane. The examination determined that the left aileron/wing of the Cessna 172 likely contacted the right horizontal stabilizer of the Cessna 180 in flight. The outboard portion of the left wing on the Cessna 172 was structurally compromised, rendering the airplane uncontrollable. Regulations required that each person operating an aircraft maintain vigilance so as to "see and avoid other aircraft."

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.