Pilot miscalculation of mountain terrain and the effects of high-altitude atmosphere were the probable causes of a fatal plane crash Oct. 5, 2020, near Telluride, according to the National Transportation Safety Board.
On Dec. 14, the NTSB released a final report on the crash of the single-engine plane that killed newlyweds Costas John Sivyllis, 30, and Lindsey Vogelaar, 33, both of Port Orange, Florida.
After taking off from the Telluride Regional Airport at 12:45 p.m., Sivyllis turned east toward high mountain terrain, and crashed 10 to 15 minutes later in Ingram Basin at 11,823 elevation, according to the San Miguel Sheriff’s Office.
Sivyllis flew his 1964 Beechcraft Bonanza single-propeller airplane and Vogelaar was the only passenger.
The NTSB report stated the airplane was in a gradual climb for about 8 miles into a box canyon then made a right turn to the south just before impacting terrain. No known radio distress calls were received from the pilot. The airplane wreckage showed evidence of a nearly vertical impact.
The surrounding terrain to the north, east, and south was higher than the accident site elevation, with peaks ranging from about 12,000 to 14,000 feet. The airplane could not gain enough altitude to traverse the high terrain.
The report said data showed the airplane did not climb toward the west where there was lower terrain.
The report’s probable cause and findings concluded that “the pilot’s loss of control during the climb to cruise flight resulting in the airplane’s impact with terrain. Contributing to the accident was the pilot’s decision to not climb to a higher altitude before proceeding over high terrain.”
In addition, the calculated density altitude in the area of the accident site was about 13,604 feet, which would have diminished the airplane’s climb performance, the report stated. There was no significant turbulence in the area.
High-density altitude is a condition where the thinner atmosphere in high mountains reduces an aircraft’s performance capability, according to the National Weather Service.
Effects include reduced power because the engine ingests less air to support combustion, reduced thrust where the propeller has less grip, reduced lift, and smaller rate of climb.
An autopsy on Sivyllis was performed by the Division of Forensic Pathology, Montrose Memorial Hospital. His cause of death was multiple traumatic injuries.
Toxicology tests performed by the Federal Aviation Administration Forensic Sciences Laboratory were negative for drugs and alcohol.
The NTSB report stated that post-accident examination found no preimpact anomalies with the air frame, engine, flight controls, and propeller. Flight control continuity was confirmed from the cockpit to all flight control surfaces.
Weight and balance calculations showed that the airplane, including the full fuel tanks, the two occupants, and all baggage, was about 300 pounds under maximum gross takeoff weight.
Sivyllis was a professional commercial air carrier pilot. The available evidence did not show the amount of high-altitude mountain flying experience that he had accumulated in single-engine airplanes.
The couple had eloped to Telluride and held a small wedding Oct. 1, 2020. They were on an adventure-filled honeymoon and were documenting it online for friends and family to follow, according to the Sheriff’s Office.
Both worked in the airline industry. Sivyllis was a United Airlines pilot and a flight instructor.
The couple were heading back to Florida with a possible stop in Oklahoma to refuel.
Before arriving in Telluride Sept. 29, 2020 the plane had left from Daytona Beach, Florida, on Sept. 28, with stops in Meridian, Mississippi; Oklahoma City, Oklahoma; and Del Norte, Colorado, according to the aviation website FlightAware.
The plane is recorded as taking a 17-minute round-trip flight Oct. 1, from Telluride Regional Airport. Before its fatal flight, the plane had taken off at 11:03 a.m. for a 53-minute round-trip flight from the Telluride airport.
At the time of the plane’s final flight, weather conditions at Telluride Regional Airport were clear with 10 miles visibility, according to the National Weather Service. Wind was 12 mph out of the west, with gusts up to 20 mph.
The NTSB report included information on preventing similar accidents.
“Pilots with limited or no training in mountain flying can be surprised about their aircraft's different performance at high density altitude, often leading to serious or fatal accidents,” the report stated. “Wind and other weather phenomena interacting with mountainous terrain often lead unsuspecting pilots into situations that are beyond their capabilities.”
The NTSB had the following recommendations:
- Flight instructors should encourage their students to attend a quality mountain flying course before attempting flight in mountainous terrain or at high-density altitudes.
- Pilots should consult with local flight instructors before planning a flight into mountainous terrain. Even experienced mountain pilots may not be familiar with local conditions and procedures for safe operations.
- Fixed-base operator staff should be alert for customers who appear to be planning flight into mountainous terrain who could benefit from mountain flying instruction.
- Pilots should be aware that weather interacting with mountainous terrain can cause dangerous wind, severe turbulence, and other conditions that may be unsafe for aircraft, especially light general aviation aircraft.
- Pilots who fly in mountain terrain should have emergency and survival gear immediately accessible in the event of a crash. Without it, a pilot or passenger who survives a crash in the mountains may not survive the harsh environment long enough for rescuers to reach the location.
The crash of the Beechcraft Bonanza was the second crash within 10 days in Telluride in fall 2020.
Previously, on Nov. 26, a single-engine private plane on approach to Telluride Regional Airport crashed east of Telluride, according to the San Miguel Sheriff’s Office. The pilot and passenger were killed.
The single-engine private plane was on approach to the Telluride Regional Airport at 1:30 p.m. when the airport lost contact. Several witnesses reported seeing the aircraft go down.
The NTSB is also investigating the crash, and a final report has not been released yet.