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Some decades ago, aircraft had really difficulties to take off and land at high altitude airports in hot weather.

I'm not sure whether advanced FADEC and better mastering of aerodynamics might today allow a heavily loaded and fully fueled FedEx MD11 to take off from 5000+ feet elevation airport in hot weather.

I'm curious to know about how much progress there was over the last 20 years or so.

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    $\begingroup$ I really can't work out what you're asking. I started to write a comment about how your question is based on a false premise but I realised I can't actually figure out what your premise or your question is. What do you mean by "a real improvement in these 'worst-of-ll' kind of scenarios"? (What does the thing in quotes even say?) Is your question, essentially, "Are modern aircraft designs better able to deal with hot and high conditions than older aircraft were?" $\endgroup$
    – David Richerby
    Commented Apr 5, 2017 at 19:22
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    $\begingroup$ It might also help to explain how you expect a fancy FADEC to help the fact that you're sucking a smaller mass of air into the engine and that the wings are acting on a lower mass of air (because heat and altitude both mean lower pressure, which means less air per given volume). $\endgroup$
    – David Richerby
    Commented Apr 5, 2017 at 19:25
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    $\begingroup$ The edit was a good attempt at clarifying the question, but I don't think it's what the asker intended. The MD-11 first flew in 1990, so it doesn't have the modern aerodynamics or control systems that the asker seemed to want to compare with equivalents from the last 20 years or so. $\endgroup$
    – David Richerby
    Commented Apr 5, 2017 at 20:13
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    $\begingroup$ The FADEC may simplify the process of performing a derated takeoff but it can't change the laws of physics. High and hot means you need more runway and when you run out, you need to reduce weight if you want to take off safely. There's reason why KDEN has a 16000 foot runway. $\endgroup$
    – Gerry
    Commented Apr 6, 2017 at 3:15

2 Answers 2

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1. Thrust / FADEC

FADEC does not increase the thrust of jet engines. If anything it limits the thrust; the MD-11 has an emergency power overboost bar that disables the FADEC protections.

enter image description here
(YouTube) Instructor holding the aforementioned bar.

Whereas in crisis (for example, imminent terrain contact), a non-FADEC engine can produce significantly more than its rated thrust, a FADEC engine will always operate within its limits.

— Wikipedia

2. Lift

Aerodynamic advances sure help. But they can't make the air denser. Hot and high conditions still limit aircraft performance.

3. Tires

Tires are better now, but even with an extremely long runway, they can't withstand the speed needed to lift off fully fueled and loaded from a hot and high airport. (Higher speed is needed because of the thinner air and high takeoff weight.)

4. Number of engines

The more engines you have, the better performance you get, namely if an engine fails on takeoff, you'll have more power left on a quad-jet versus a twin-jet (3/4 vs. 1/2).

MD-11

In this answer, you see the MD-11F needs to stop for fuel mid-journey because it takes off from a hot and high airport.

  • The answer to the main question is no—the tires would burst at the required high takeoff roll speed given an adequate runway length and zero (hypothetical) climb limitations.

Boeing 787 (21 years later)

In this other answer, you see a not particularly high airport, but hot, limits the amount of passengers on the 787 headed from Vegas to Europe.

The first linked answer examines the physics behind hot and high, and the 787 answer examines a real life scenario with real numbers.

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"High and hot" covers a wide range of conditions. In addition, total takeoff distances are subject to a number of factors including, but not limited to takeoff weight, field elevation, type and condition of runway, surface winds, obstacle clearance, etc.

So an MD-11 with a low payload and a meaningful headwind can depart the same airport successfully that could not be done if it were loaded at or near MTOW with a tailwind. You will have to be a little more specific.

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    $\begingroup$ This is a comment asking for the question to be clarified, not an answer. $\endgroup$
    – David Richerby
    Commented Apr 6, 2017 at 8:32

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