Into Thin Air: Clear Skies, High Terrain and a Slow Climb
On a clear July evening, a 12,000-hour pilot ferrying a Bonanza G36 out of Aspen turned down an IFR departure and flew east VFR, climbing a few hundred feet per minute toward rising terrain. The airplane turned into a bowl ringed by 13,000-foot peaks and hit the mountain. Based on the AOPA Air Safety Institute case study and the NTSB final report, a look at performance and terrain.
Clear skies can be the most dangerous weather in the mountains, because nothing about them says stop. The risk on a warm afternoon at a high airport is the airplane itself, and how little climb it has left.
The AOPA Air Safety Institute (ASI) re-creates this flight in its video "Accident Case Study: Into Thin Air," which you can watch below. The summary that follows is ours and is based on the NTSB final report (CEN21FA305), which also gives the official probable cause. Watch the full case study for ASI's own analysis.
The flight, in short
On July 3, 2021, a 58-year-old airline transport pilot with an estimated 12,000 hours was ferrying a Beechcraft G36 Bonanza to its owner's home field in New York. The owner, a private pilot who had bought the airplane in April, rode along. They stopped at Aspen (ASE), elevation 7,720 feet, for fuel and lunch. The temperature there was 25°C.
The pilot asked for an IFR clearance to Des Moines. The clearance included the LINDZ Nine departure, which required climbing to 16,000 feet. He said he couldn't accept 16,000 feet and would depart VFR instead. Asked whether he'd fly down the valley or go east through the ridge, he said he'd decide “once we see what's going on” after takeoff.
He circled near the airport to climb, at 340 to 360 feet per minute, and headed east once past 10,000 feet. The terrain rose and the climb rate fell. At 6:36 PM the airplane was at 10,820 feet, about 600 feet above the ground, climbing 150 to 250 feet per minute. Two minutes later, at about 11,300 feet, it turned into a semicircular bowl where the peaks reached about 13,000 feet, turned left and hit trees and rising terrain. Both people aboard were killed. The NTSB found no problem with the airplane or engine. It could not determine how much experience the pilot had in single-engine piston airplanes or flying through the Rockies, or whether he was prepared to fly the mountain pass visually.
The NTSB determined the probable cause to be: “The pilot’s failure to navigate through mountainous terrain, which resulted in controlled flight into terrain.”
Why performance and terrain matter
The airplane was doing about what its manual said it could at that altitude. The trouble was a route that asked for more climb than it had. Heading for a pass without a fixed plan left few options once the terrain rose faster than the airplane could climb.
- Work out climb performance for the actual temperature, elevation and weight before a mountain departure.
- Pick your route out of a mountain airport on the ground, not after takeoff.
- Climb over the airport until you have the altitude to clear the pass with room to spare.
- Approach ridges and passes at an angle so you always have room to turn away toward lower terrain.
Putting it into practice
Why it matters
Experience in one kind of flying doesn't carry over to every kind. A departure you haven't flown, in an airplane you don't fly often, deserves a plan as careful as any approach in bad weather. PlaneWX never recommends GO or NO‑GO. The pilot makes the call.
Decision loop
- 1Weather Briefing
- 2FRAT
- 3GO / NO-GO
- 4Self Debrief
Mentor is an optional layer on any step, not a fifth stage.
Tool or habit
Brief the weather in PlaneWX, then use the FRAT, which opens 4 hours before departure, to think through the rest of PAVE: how current you are in this airplane, the terrain and conditions on the route, and any pressure to keep the trip moving. You record your own GO / NO‑GO decision.
Sources
- AOPA ASIAOPA Air Safety Institute: Accident Case Study: Into Thin Air (video)
- NTSBNTSB Aviation Investigation Final Report CEN21FA305 (N36JJ)
PlaneWX complements FAA and Flight Service weather products. PlaneWX is decision support. It is not a substitute for your full preflight briefing (for example a standard briefing through Flight Service or your EFB).