Too hot to fly Legally?

SixPapaCharlie said:
So I am doing some check ride prep and I meet with a local CFI and I pull out the takeoff distance chart from my POH today and he says "What is the max takeoff temp for your aircraft?"
What do you folks (not Comanche pilots) in Phoenix do when it is 130 out?

I moved from Phoenix to Colorado.
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Imo, on a commercial operation, if the pilot cannot determine runway needed, it’s a no go.

Source: common sense
 
How about elevation? Is it illegal to takeoff in a Cessna 172 from, say, for example, Leadville, CO on a summer day? The POH data only goes up to 8000. Field elevation there is 10,000.
 
sarangan said:
How about elevation? Is it illegal to takeoff in a Cessna 172 from, say, for example, Leadville, CO on a summer day? The POH data only goes up to 8000. Field elevation there is 10,000.
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Does the data truly only go to 8000, or is that a suppose it does?
 
schmookeeg said:
Today's secret word (for the CFI) is "Extrapolate" :)
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Remember increased takeoff distance is not linear, although if it’s that close you shouldn’t be taking off.
POH charts don’t show the effects of humidity either, you can lose up to 10% of engine power under high humidity conditions.
 
The manual for my ride doesn't have any chart with takeoff distances vs. temperature.

I don't know what to do.
 
Kritchlow said:
Does the data truly only go to 8000, or is that a suppose it does?
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And now I've looked in my Cessna 172S manual, and it does only go up to 8000, and max temperature (for any altitude) is 40 C (104 F).

Clearly there are flight schools in Phoenix operating at temperatures of more than 40 C for most of the summer. And flight schools in Colorado routinely operate 172S's into Leadville. They're not doing it illegally.

The main reason for such limitations on Part 121 and 135 operators is because those operators generally fly airplanes that are much more runway-limited. Meaning the runways are much closer in length to the actual runway length required. For a 172 or most other light GA airplanes, the runway length available is typically so much greater than that required, that errors introduced during extrapolation don't typically matter a whole lot. The largest number on that 172S takeoff chart is 40 C and 8000 feet pressure altitude, which is a ground roll of 2450 ft. If you're at Leadville (elevation 9934) and the temperature is a more normal summer day of 25 C (like the forecast is today), I'll bet even the worst extrapolation will result in a ground roll of less than the 6400 feet available.

Now, if you wanted to take off from 0CO2, elevation 8980, length 4000, then a little more care should be exercised. There are all kinds of books written about that topic and how to apply rules of thumb and such to try to mitigate risks. But again, it's not a violation of the FARs.
 
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schmookeeg said:
Today's secret word (for the CFI) is "Extrapolate" :)
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Sounds good except that the loss of performance due to density altitude is not linear. And some POH point out it should not be done. OTOH, they are generally informational and not limitations. If they were limitations, there's a whole bunch of pilots in Colorado who would not be flying. So extrapolation, with a healthy buffer, is a fact of life, as are tools like the Koch chart and rule of thumb like the 70% of takeoff speed/50% of runway.

Koch Chart is interesting. I used it a lot in instruction last summer when I was teaching in a Sportcruiser, which shows only sea level takeoff and landing performance.
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Kritchlow said:
Imo, on a commercial operation, if the pilot cannot determine runway needed, it’s a no go.

Source: common sense
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Also maybe not the correct answer on a scenario-based checkride, since that kind of a cop out. The real question is, if your client wants to go, can you manage to do it safely and legally?
 
SixPapaCharlie said:
So I am doing some check ride prep and I meet with a local CFI and I pull out the takeoff distance chart from my POH today and he says "What is the max takeoff temp for your aircraft?"
I go "Dude its a Comanche 250, it will take off from the surface of the sun. duh!"

He says well, your take off calc chart in the book only goes up to 100. Legally, can you go fly?
I go "Didn't you hear the part about the surface of the sun? We good!"

His comment was that since the numbers don't go to whatever the hell Texas is doing right now, we don't have the performance data and need to have it if we want to fly in these temps.

What do you folks (not Comanche pilots) in Phoenix do when it is 130 out?

Can I just supply the performance data to Piper? Allegedly I may be aware that it performs just fine in temps well above 100. Allegedly.
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I remember the day I took my ppl checkride in Casper, WY back in 1978. It was 102 degrees and field elevation is 5344 ft. The DPE showed me a density altitude chart and told me to show him the DA. I held my hand about a foot above and to the right of the page and told him it was somewhere in this area because the chart didn't go that high. He told me I had the right idea which was his concern. He wanted to emphasize the importance of DA in higher elevations like Casper. It was about like taking off from Leadville. I believe I used about half of the 10,000 ft. runway. LOL
 
eman1200 said:
I thought maybe this was a line you used on a chick........."you are waaaay too hot to fly, legally speaking".

I didn't say it was a good line.......
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It worked, remember? Saturday? At the Gentlemen's Club?
 
Kritchlow said:
Imo, on a commercial operation, if the pilot cannot determine runway needed, it’s a no go.
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I agree. But since the performance charts are not a limitation (and are arguably not even accurate except with a brand new airplane), they are not the sole method of determining acceptable runway length.
 
midlifeflyer said:
If every time someone was wrong about something, we discounted everything they said, we'd listen to literally nobody.
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The problem is that clown is teaching and peddling nonsense, and the people he teaches go on to repeat the same nonsense. And they don't have the inclination to go actually look it up.
 
Doc Holliday said:
The problem is that clown is teaching and peddling nonsense, and the people he teaches go on to repeat the same nonsense. And they don't have the inclination to go actually look it up.
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Always question authority, unless the authority is saying what you want to believe.
 
brcase said:
If it works and you take off without incident it was "reliable information", if you have an incident related to takeoff distance then it wasn't "reliable information"

Brian
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“We made it 100 yards further than last year”?
 
Doc Holliday said:
The problem is that clown is teaching and peddling nonsense, and the people he teaches go on to repeat the same nonsense. And they don't have the inclination to go actually look it up.
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You interpret me asking for clarification on a forum as "Going on to repeat the same nonsense"?
Feels like I came here questioning if what I was told is accurate. He suggested I see of there were any updated information published that includes data for hotter temps.
I apologize for doing any level of research in your presence oh great and wise one. What it must feel like to be the smartest person in every room you enter.
 
SixPapaCharlie said:
You interpret me asking for clarification on a forum as "Going on to repeat the same nonsense"?
Feels like I came here questioning if what I was told is accurate. He suggested I see of there were any updated information published that includes data for hotter temps.
I apologize for doing any level of research in your presence oh great and wise one. What it must feel like to be the smartest person in every room you enter.
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It takes a few minutes of research to find out information, especially when it comes to regulations. You wish to be a commercial pilot, which means you must have a greater understanding of regulations especially in the area of aircraft performance.

And I feel relatively confident you'll never be mistaken for the smartest person in any room. ;)
 
Doc Holliday said:
It takes a few minutes of research to find out information, especially when it comes to regulations. You wish to be a commercial pilot, which means you must have a greater understanding of regulations especially in the area of aircraft performance.

And I feel relatively confident you'll never be mistaken for the smartest person in any room. ;)
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And I am ****ing trying to learn! You are giving me **** because I admittedly question something and I am seeking more knowledge you miserable hypocrite.
Why even be on a forum if you are going to **** on people for asking questions. ****ing block me already.
 
I suspect that the instructor was asking a scenario based question, not telling 6PC not to fly? If so, that's actually well within the bounds of check ride prep.
 
There is a missing item in this discussion. I had two "Gadgets" in my flight case, each capable of answering the question.

Airforce issued circular slide rule, E6B, or something of that sort. You calculate density altitude, and performance reduction.

DENALT circular slide rule, also military issue, For calculating runway requirements at high altitudes or high temperatures. Front for fixed pitch, back for variable pitch.
The DENALT was much smaller, and easy to use, so first choice.
The E6B was larger, but used for flight planning fuel use, and time to destination, so more likely to be at hand.

Colorado Springs calculation was 5,000 feet of runway, Cessna 172, and was accurate. The POH could have been used, with extrapolation, I have done that, but the calculators are much more accurate, as the effects are not linear. It was August, and density altitude was way up. We had only one mid size suitcase for the two of us, so relatively light for this trip.

Do the electronic devices have this capability? Why has no one proposed using them to determine the runway needed, and compared to the runway available?
 
If the limitations section doesn't prohibit operations above a certain temperature then your CFI is full of ****.

There can be temperature limits for reasons other than performance, like the resin strength they made the composite wings out of.
 
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