Hot and high

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In aviation, hot and high is the ability of an airplane to operate safely from airports in very warm climates or very high elevations.

Warm air has a lower density than average, and the air at high elevation also has a lower density than at sea level. A lower air density means a reduction of the amount of lift generated by the airplane wings. This means that aircraft need a longer takeoff run than usual.

As a consequence, particular models of aircraft can not operate from "hot and high" airports with profitable loads.

The Boeing 707-220 was a 707-120 airframe fitted with more powerful Pratt & Whitney JT4A engines, civilian versions of the military J75, for hot and high operations - only 5 of these were built, all for Braniff International Airways due to extremely high fuel consumption. This variant was rendered redundant by the arrival of the turbofan.

Less formally, "hot and high" can also describe a botched landing approach, where a fixed-wing aircraft is too fast (hot) and too high above the glide path: since the only way to increase the rate of descent is to increase speed, and the aircraft is already too fast, it is unlikely that the approach can be salvaged.

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