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Density altitude case study

Draker

Well Known Member
Not really Vans or experimental related, but Air Safety Institute recently posted a new "Accident Case Study" video on the topic of density altitude. As someone who did almost all of his flying in Florida, density altitude has always been this abstract concept to me: something I learned the math on as part of my PPL, but have never practically encountered its effects. I suppose it's one thing to draw the graphs of horsepower and climb performance vs. density altitude, and another thing to deal with it in the air. Maybe this topic is obvious to you highly experienced pilots, but I found the video eye opening. Definitely something to take seriously now that I'm a stone-throw from the Sierras.
 
Not really Vans or experimental related, but Air Safety Institute recently posted a new "Accident Case Study" video on the topic of density altitude. As someone who did almost all of his flying in Florida, density altitude has always been this abstract concept to me: something I learned the math on as part of my PPL, but have never practically encountered its effects. I suppose it's one thing to draw the graphs of horsepower and climb performance vs. density altitude, and another thing to deal with it in the air. Maybe this topic is obvious to you highly experienced pilots, but I found the video eye opening. Definitely something to take seriously now that I'm a stone-throw from the Sierras.

Same, PPL out of Lakeland but luckily I got current again here in high Wyoming.

To keep it RV related; the RV line for the most part has such good performance it usually doesn’t make me worry too much. However, this is a dangerous thought that can get a guy in trouble. When density altitude is up around 12k and you are fully loaded it is surprising how different the plane handles and performs.

I also do a fair bit of mountain crossing but take a conservative approach. No way would I try and climb up a valley.
 
KSQL

Not really Vans or experimental related, but Air Safety Institute recently posted a new "Accident Case Study" video on the topic of density altitude. As someone who did almost all of his flying in Florida, density altitude has always been this abstract concept to me: something I learned the math on as part of my PPL, but have never practically encountered its effects. I suppose it's one thing to draw the graphs of horsepower and climb performance vs. density altitude, and another thing to deal with it in the air. Maybe this topic is obvious to you highly experienced pilots, but I found the video eye opening. Definitely something to take seriously now that I'm a stone-throw from the Sierras.

I used to be based out of KSQL, not too far from you. Since I trained for my PPL in Boston, I decided to do some mountain flying with an instructor as soon as I went out West. We flew over to the Sierras. By the time the day was done, I had a whole new appreciation for how high altitudes, high temperatures, and heavy loading impacts performance. I’d recommend that experience at a minimum to anyone who is new to the mountain west. Even though I’ve done a fair bit of mountain flying since (I now live in the PNW), the day I spent is all that was needed to have saved the life of those pilots in the video.
 
Thanks for posting this...
Lost a friend to this very thing.
The video does a good job explaining things.
 
Thanks for posting that and bringing attention to density altitude (DA).

Every summer a number of airplanes are torn up and pilots killed in these parts because of this issue. We all suffer from the occasional fit of invulnerability - I certainly do - but I wish this was higher on most pilots mind when they come out here to the mountains. Occasionally we (local pilots) intercept a few of these folks but obviously not often enough. A C-172 (or similar) with four people onboard stopping on a nice 100 degree afternoon to top off their tanks before starting over the continental divide is often a good indicator to go over to the fuel pump and have a friendly chat with the pilot. Most don't listen but I'd like to think that putting the thought in their head helps a little bit.
 
I got my PPL in Alabama and did all the book learning about DA. When I moved to Colorado I took a mountain flying course but what really made it sink in was doing a flight review at KFLY on a hot summer day in a C-172 and barely being able to climb out after takeoff.

Being based at 8300 feet is one reason I ended up with an RV :)
 
I saw in the video that they were unable to determine the mixture setting. [RV related]: some years back a jet jockey purchased an RV10, then complained, here on VAF, about its poor performance (speed, climb rate) as he got into the mid-teens. Turned out he was running full rich. In his mind, more gas = more power. Of course, there’s also the bit about filing ifr for a route with a 16,000’ MEA, then being surprised at their clearance and telling ATC “unable”. Makes me wonder about these guys.
 
Density Altitude

Two memorable accidents: both early to mid afternoon in summer. One chose an airport where the long runway was closed. Short runway was 4600' at 7000' plus elevation.
One was a small engine Cessna Cardinal, left a runway in mostly flat valley terrain, flew 80 miles to top off with cheaper fuel. Both crashed on takeoff, fatal to all on board.
I tell people with marginal airplanes to be on the ground for the day at 11 am and airborne the next day at sunrise.
At Gallup I heard a airplane call in that I was pretty sure was a homebuilt. A few minutes passed and no airplane. Almost dark, it looked like an airplane sitting on the runway a long ways from the FBO. We drove down there and the airplane was sitting there with engine stopped. Pilot said it quit and I can't get it started. I said crank the engine and i will handle the mixture. Full lean, it started quickly and I adjusted the mixture. I found out later the airplane was new t him and most of his experience was in turbine helicopters. He knew nothing about mixture requirements at high elevations.
 
Not really Vans or experimental related, but Air Safety Institute recently posted a new "Accident Case Study" video on the topic of density altitude. As someone who did almost all of his flying in Florida, density altitude has always been this abstract concept to me: something I learned the math on as part of my PPL, but have never practically encountered its effects. I suppose it's one thing to draw the graphs of horsepower and climb performance vs. density altitude, and another thing to deal with it in the air. Maybe this topic is obvious to you highly experienced pilots, but I found the video eye opening. Definitely something to take seriously now that I'm a stone-throw from the Sierras.

quote in the video "out of their element, the flatland pilots in this tragedy"......
 
Yeah, density altitude is a real thing up here. I completed my multiengine training in the late summer, many years ago, in a Piper Seminole.

Single engine climb performance was a negative number. Not joking. As I recall, it was something like -300 fpm. Kind of defeats the purpose of flying a twin for engine redundancy.
 
But the thoughtful folks at Piper offered you a product that doubled your chances of an engine failure while assuring the aircraft could still fly all the way to the crash site.

Give credit where it's due.
 
Crossing the Rockies

Having just crossed the Rockies for the first time I was cautious about my path. Being a flatland pilot most of the time, I was concerned about the trip and this is exactly why. Getting caught in a canyon is very real.

I can't imagine knowing I going to fly into terrain and can't do anything about it. They made some unfortunate decisions.
 

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Having just crossed the Rockies for the first time I was cautious about my path. Being a flatland pilot most of the time, I was concerned about the trip and this is exactly why. Getting caught in a canyon is very real.

I can't imagine knowing I going to fly into terrain and can't do anything about it. They made some unfortunate decisions.

I'd say you made an excellent choice with your path. We stopped in Rock Springs this summer on a day with a 9000' DA. No issues for the RV, even at gross, but that's partially due to their insanely long runway (I ate up 2000ft on the ground roll) and literally nothing to hit in the immediate vicinity. I wouldn't even think of trying that on a shorter runway with trees at the end.

It seems like they hadn't studied their route enough in this scenario. I'm really at a loss as to why someone would choose to make a fuel stop at such a high risk environment in the first place. Stopping in Rifle or Eagle would have made a lot more sense. Even better, detouring along I-80 to the North would have added a negligable amount of time to the trip.
 
Thanks for sharing. I saw something similar decades ago in a safety class. Guys had videotaped their own demise and the camcorder was found in the wreckage months later. It was eerie watching the 10 minutes leading up to the crash, wanting to will them to turn around while they were oblivious to what was coming up.
 
Take mountain flying class so you know what to ask

Having flown out of Aspen many times, you need to know what you are doing there. I was never PIC but even in our company Citation the pilot did the numbers.

Sometimes a person doesnt know what to ask and it turned out fatal in this case. Aspen is a great place to live and the food is some of the best in the world, but not the best for summer flying. Their route from Napa through SLC - Rock Springs would have put them at 9500 max and they would be talking about their trip now.

Had they tried Independence Pass they may have made it. Had they flown up the side of the canyon, they may have made it. Had they gone down valley through Glenwood Canyon - they would have made it. One call to ATC to ask or checking with the guys at Atlantic would have made all the difference.

Sad story.
 
Rock Springs

Rock Springs was my first high density altitude experience with a low powered airplane.
Wittman Tailwind, 85 horsepower, no mixture control. On the plus side only had 25 gallons fuel, by myself with heavy baggage. Density altitude 10,500'. Wind was straight down the long runway. After a lot of discussion with myself I decided I would try it and if not airborne by the halfway mark abort the takeoff.
About 2500' of runway used, a somewhat slow climb to 14.5 and went to Elko where I spent the night.
 
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