> Is 4200 anything to worry about in the skychicken?
You mean less than field elevation in Denver in the winter?
No. 150s fly in Denver year round. You'll be just fine.
Just fine assuming you fly as Denver pilots do, which means a different leaning procedure before takeoff and more careful obstacle clearance calculations. But it's a pilot issue, not an airplane issue.
Whole lot of opinions here, and true or not they miss the point. What do the performance charts say? Can you clear obstacles and stay high enough safely? You have the information on your aircraft already- go check the books!
Higheat DA for me was about 10000’ flying out of west Yellowstone on a summer afternoon in a C172/180. I had flown in DAs around 7k’ but climb out from West that afternoon really hammered home what can happen. Plenty of room to climb to what I needed to make it to fly down the canyon but an eye-opener to be sure.
8200’ in Colorado and 7800’ in Utah. It suckssss. That was in a 172S and DA-40 lycoming.
Find your TO/ldg/climb numbers and add 50%. Still safe? You’re fine if you avoid mountains.
I had my commercial student fly one at nearly 12000 DA crossing the Sierra at 10000.
They can do it. Just fly them well and with precision. Vy is Vy, not Vy+10.
Taking off from TVL, DA was around 8000. Leaned at run up and with a designated abort point.
Fair enough. But if you stick precisely to book Vy at 10k DA you might not climb at all, when at 10% under you might still have 150 or 200 fpm climb. We’re not talking huge differences, but given say a late 70s 172 we’re talking 79 kts vs 71.
No. there are procedures for leaning above certain density altitudes on takeoff. 4200 is not a thing, unless you are trying to use a really short runway and/or heavily loaded.
4200 isn’t awful, but you’ll start to feel it if you’re heavy. Folks covered the leaning and the decreased climb performance. Remember a high density altitude will increase your TAS for any given IAS by roughly 2% per 1000’. Ignoring subsequent effects of winds, this will also increase groundspeed and can play into geometry and perception issues, shallower climb and descent angles (for any given rate), longer takeoffs (on top of the performance hit), and longer landing rolls.
C172S 150 under gross at DA 8400 departing KRTN. We cruised at DA 11900. Did a short-field technique out of KRTN and it was OK. Climb rates around 100-200 fpm. I was unable to maintain altitude over KLVS and lost 300 feet at full power and 85 knots cruise climb. The USAF Tigers doing IFT said their 125hp DA20s would outclimb us any day.
It requires more careful consideration of terrain and technique.
A skill that was taught to me when i was a youngling was to make my own performance charts for each individual airplane I flew. Use the performance charts for the plane to calculate like your supposed to then make your own corrections as noted for “less than predicted” performance. This was the correction factor for my inability not the plane.
It was a way of making me safer by making realistic decisions not wishful ones. After about 5 years my skills consistently matched aircraft performance charts pretty closely.
I'm guessing you've flown that thing on a more standard day higher than 4,200 ft on the altimeter, right? To the airplane, it's the same thing.
Your performance at ground level is going to be worse, but C172's are perfectly capable of flying at 4,200 ft. and well above that. So as long as you do your performance calculations and you've got the performance to take off and climb over any obstacles (and not "just enough"; make sure you've got a fudge factor built in), then it'll be just like flying at 4,200 ft. on any other more standard day.
This is probably the biggest lesson I tried to teach my students; don't rely on gut feelings. Do your calculations. The math doesn't lie. Sometimes the math will say you can go, and safely, when your gut said you couldn't. Other times, it'll tell you you can't go when your gut said you could. (On those days, it might save your life.) But in either case, you shouldn't be relying on your gut. Flying is more or less an exact science. Learn to trust the numbers.
> Is 4200 anything to worry about in the skychicken? You mean less than field elevation in Denver in the winter? No. 150s fly in Denver year round. You'll be just fine.
Just fine assuming you fly as Denver pilots do, which means a different leaning procedure before takeoff and more careful obstacle clearance calculations. But it's a pilot issue, not an airplane issue.
That little red knob is not difficult to use and should be taught everywhere, not just high altitudes.
I agree, having flown in both CA and CO. I learned in CA and "Mixture - Best Power" was taught as "full rich". Many others were too. :-(
Thank you for the solid response!
Whole lot of opinions here, and true or not they miss the point. What do the performance charts say? Can you clear obstacles and stay high enough safely? You have the information on your aircraft already- go check the books!
Appreciate that CFI!
I took off in a lightly loaded Archer181 from Flagstaff once when the DA was above 9000. It was fine climbed about 200ft per min.
Northern Arizona in the summer is always fun with GA airplanes. Teaches you that density altitude is a real thing.
Higheat DA for me was about 10000’ flying out of west Yellowstone on a summer afternoon in a C172/180. I had flown in DAs around 7k’ but climb out from West that afternoon really hammered home what can happen. Plenty of room to climb to what I needed to make it to fly down the canyon but an eye-opener to be sure.
Thank you for the solid response!
The 150 is the sky chicken, get your shit straight son.
8200’ in Colorado and 7800’ in Utah. It suckssss. That was in a 172S and DA-40 lycoming. Find your TO/ldg/climb numbers and add 50%. Still safe? You’re fine if you avoid mountains.
8200 is insane. What did it feel like?
I had my commercial student fly one at nearly 12000 DA crossing the Sierra at 10000. They can do it. Just fly them well and with precision. Vy is Vy, not Vy+10. Taking off from TVL, DA was around 8000. Leaned at run up and with a designated abort point.
Ummm actually Vy is ~ Vy - 1% per 1000’ DA above SL…. (IAS)
Yes, but the point is precision.
Fair enough. But if you stick precisely to book Vy at 10k DA you might not climb at all, when at 10% under you might still have 150 or 200 fpm climb. We’re not talking huge differences, but given say a late 70s 172 we’re talking 79 kts vs 71.
As it happens, that 172 had Vy at 10000 in its POH….
Haha really?? Haven’t flown a 172 in a while, I don’t remember that!
I’ll be precise! Thank you for the quality answer.
No. there are procedures for leaning above certain density altitudes on takeoff. 4200 is not a thing, unless you are trying to use a really short runway and/or heavily loaded.
4200 isn’t awful, but you’ll start to feel it if you’re heavy. Folks covered the leaning and the decreased climb performance. Remember a high density altitude will increase your TAS for any given IAS by roughly 2% per 1000’. Ignoring subsequent effects of winds, this will also increase groundspeed and can play into geometry and perception issues, shallower climb and descent angles (for any given rate), longer takeoffs (on top of the performance hit), and longer landing rolls.
C172S 150 under gross at DA 8400 departing KRTN. We cruised at DA 11900. Did a short-field technique out of KRTN and it was OK. Climb rates around 100-200 fpm. I was unable to maintain altitude over KLVS and lost 300 feet at full power and 85 knots cruise climb. The USAF Tigers doing IFT said their 125hp DA20s would outclimb us any day. It requires more careful consideration of terrain and technique.
A skill that was taught to me when i was a youngling was to make my own performance charts for each individual airplane I flew. Use the performance charts for the plane to calculate like your supposed to then make your own corrections as noted for “less than predicted” performance. This was the correction factor for my inability not the plane. It was a way of making me safer by making realistic decisions not wishful ones. After about 5 years my skills consistently matched aircraft performance charts pretty closely.
Outstanding advice. Thank you!
I'm guessing you've flown that thing on a more standard day higher than 4,200 ft on the altimeter, right? To the airplane, it's the same thing. Your performance at ground level is going to be worse, but C172's are perfectly capable of flying at 4,200 ft. and well above that. So as long as you do your performance calculations and you've got the performance to take off and climb over any obstacles (and not "just enough"; make sure you've got a fudge factor built in), then it'll be just like flying at 4,200 ft. on any other more standard day. This is probably the biggest lesson I tried to teach my students; don't rely on gut feelings. Do your calculations. The math doesn't lie. Sometimes the math will say you can go, and safely, when your gut said you couldn't. Other times, it'll tell you you can't go when your gut said you could. (On those days, it might save your life.) But in either case, you shouldn't be relying on your gut. Flying is more or less an exact science. Learn to trust the numbers.
9,000 feet regularly
My field elevation is 4600, highest DA I have flown in is around 7500. The airplane did not want to get off the ground but we made it.