Robert Frayser took off from Great Bend, Kansas, in his Comanche 400 on a clear winter day. He was alone, cruising at 5,500 feet on autopilot, and headed for a meeting in Topeka.

90 minutes later, Robert crashed his plane in a field. He was confused, his head was throbbing, and he thought he was still in the air. As he started running his landing checklist, he realized where he really was. His right wing was nearly torn off from impacting a tree, but somehow he managed to survive with only a few broken bones, cuts and bruises.

But the story doesn't end there. Because his engine stopped in-flight, no one heard the plane come down. Robert had to get out and walk through snow, eventually finding a farmhouse. When he got to the hospital, doctors estimated that another 30 minutes in his carbon monoxide filled plane may have killed him.

How It Happened

So how did carbon monoxide get into his cabin in the first place? It started with a crack in the muffler.

Most small single-engine aircraft cabins are heated by passing outside air over the muffler, and then passing that heated air into the cabin. Most of the time that's not a problem, because the exhaust air and cabin air never mix. But, if the muffler is cracked, it can cause serious problems.

If you have a cracked muffler and you have your heater on, carbon monoxide can start entering the cabin. And if that happens, your first signs of carbon monoxide poisoning will most likely be these symptoms:

What To Do If You Think You Have Carbon Monoxide Poisoning

So what should you do if you start feeling the symptoms of carbon monoxide poisoning? First off, always follow your checklist, but what you'll find is most of them are very similar:

Step 1 - Turn Off The Cabin Heat
By turning off the heat, you're preventing any more toxic air from entering the cabin. But even though you've stopped the source, your cabin is still filled with CO gas.

Step 2 - Open Your Fresh Air Vents
Airplanes differ, but almost every airplane has one or multiple fresh air vents. They might be controlled on the panel, or they might be controlled near the floor or ceiling of your plane. Either way, get them all FULL OPEN. It might get cold quickly, but you're pumping fresh air into the cabin, and dumping the bad air out the back.

Step 3 - Open Your Cabin Windows
This isn't possible in all airplanes, but in many of them you can open the windows. This simply helps step 2 in getting more fresh air into the cabin.

Step 4 - Land As Soon As Practical
Find an airport near you and land. And keep in mind, your judgement and motor skills are impaired when you have carbon monoxide in your bloodstream, so you need to be extremely careful when choosing your landing spot, as well as flying yourself there.

Step 5 - Tell ATC
ATC may be able to help with vectors to an airport, and they can also coordinate medical help on the ground once you've touched down.

Step 6 - Get Medical Attention
Just because you're on the ground doesn't mean you're in the clear. It takes up to 4-6 hours for your body to exhale 50% of the carbon monoxide that you inhaled.

How To Prevent Carbon Monoxide Poisoning

The best way to prevent carbon monoxide poisoning is to keep carbon monoxide from entering your cabin in the first place. And the best way to do that is to check your muffler and heater shroud for cracks during preflight.

But the next-best method is detecting carbon monoxide as early as possible. For as little as $5, you can buy a carbon monoxide detector on Sporty's and Amazon. These detectors will give you the heads up you need to act before you pass out in your plane. And if you ask us, that's a pretty cheap insurance policy for your next winter flight.