Cottage Grove, MN, USA
N8488L
Cessna 172
The accident flight was a “discovery flight” arranged by the rear seat passenger for his girlfriend, the front seat passenger. A flight instructor was seated in the right front seat. Flight track information revealed that, about four minutes after departure at an altitude of about 1,900 ft, the airplane entered a steep descent that continued until water contact. The airplane was destroyed when it impacted the water. Examination of the airplane revealed no evidence of mechanical anomalies that would have precluded normal operation, and no evidence of a bird strike. Visual meteorological conditions were present in the area at the time of the accident. Available medical information provided no evidence that the CFI had any medical condition, substance use, or toxic exposure that contributed to the accident. Based on the absence of detected ethanol in the CFI’s urine, it is likely that ethanol detected in his cavity blood was from sources other than ingestion. Given the available information, the reason for the airplane’s impact with terrain could not be determined.
HISTORY OF FLIGHTOn September 13, 2020, at 1432 central daylight time, a Cessna 172, N8488L, was destroyed when it was involved in an accident near Cottage Grove, Minnesota. The flight instructor and two passengers were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. According to the operator, the accident flight was a “discovery flight” arranged by the passenger for his girlfriend. Discovery flights typically included 1/2 hour of ground training and a preflight inspection of the airplane, followed by the flight, during which the front-seat passenger operated the controls to the extent possible. The male passenger was seated in the right rear seat, the female passenger was seated in the left front seat, and the flight instructor was seated in the right front seat. According to Automatic Dependent Surveillance-Broadcast (ADS-B) data, the airplane departed about 1428 and proceeded southbound until it crossed the Mississippi River, then it turned to a southeast heading. The last return from the airplane was at 1432, over Lower Grey Cloud Island at an altitude of about 1,900 ft and speed of 101 mph. The flight profile view revealed a sharp descent followed by a sharp ascent as the airplane approached Lower Grey Cloud Island; the airplane subsequently entered a steep descent that continued until impact. An aircraft performance study based on the ADS-B information indicated that the airplane lost over 1,000 ft of altitude in seven seconds: a descent rate of over 8,000 ft per minute, before impact. The pilot of another airplane, inbound to the departure airport, had a Go-Pro video camera operating in the cockpit and captured the accident airplane as it descended. Although eagles or geese were seen in the area, there was no evidence to indicate that the accident airplane collided with any of these birds. WRECKAGE AND IMPACT INFORMATIONThe wreckage was located in 70-foot-deep water and was examined at a secure facility following recovery. All control cables failed at or near their cockpit connections and the failures were consistent with overload. The cables were traced from the cabin area to their respective flight control surfaces. Both wings displayed accordion-type compression damage aft to the main spar, consistent with high-speed impact. The left horizontal stabilizer had more impact damage than the right horizontal stabilizer. The vertical stabilizer, although straight, was impact damaged, but the anticollision light on top of the tail was intact, consistent with the airplane being upright upon impact. The damaged propeller blades were bent aft into the engine compartment. The examination of the engine revealed no anomalies that would have precluded normal engine operation. MEDICAL AND PATHOLOGICAL INFORMATIONThe Ramsey County Medical Examiner performed the CFI’s autopsy; cause of death was multiple traumatic injuries, aircraft accident, and his manner of death was accident. The Federal Aviation Administration Forensic Sciences Laboratory identified ethanol at 0.051 g/dL in cavity blood and did not detect ethanol in urine.
A steep descent and impact with terrain for reasons that could not be determined based on the available information.
Source: NTSB Aviation Accident Database
Aviation Accidents App
In-Depth Access to Aviation Accident Reports
