Planes can’t take off in extreme heat because of the lower air density at higher temperatures. As warm air is less dense, a plane can’t generate as much lift.
Planes can compensate for the reduced lift if they have access to a longer runway and can climb higher.
But, this is impractical in most instances.
As a result, airlines across the globe cancel or delay flights due to extreme heat.
Climate change has currently increased the number of heat-related flight delays and cancellations.
Aircraft manufacturers will likely respond to this phenomenon with more efficient aircraft engines.
3 Reasons Why Planes Can’t Take Off in Extreme Heat
Planes don’t take off in extreme heat for the following three reasons.
1. Air Density
The upper atmosphere is already thinner than the atmosphere at sea level.
Extreme heat compounds this fact further by causing air molecules to spread even further apart, yet airplanes need more air molecules to pass over their wings to generate thrust.
2. Increased Thrust
Taking off during extreme heat requires the plane to compensate for the lack of air with higher thrust to accelerate and take off more quickly.
But, a plane can’t easily achieve higher thrust under extreme heat because hotter air has less oxygen for the engine to combust.
3. Loss of Efficiency
High temperatures decrease the efficiency of a plane’s engines, propellers, and wings.
This loss of efficiency makes it harder and less efficient to for planes to take off during extreme heat.
A plane could still take off if it has sufficient runway, but the conditions would be unideal.
Taking Off in Extreme Heat Can Be Dangerous
A plane can only take off in extreme heat if it has enough runway and can generate enough climb.
The plane would need extra runway to compensate for the lower air density during hot temperatures.
The plane also needs to climb quickly, which is unfeasible in many airports with limited runway.
So, a plane that takes off during extreme heat could safely take off. But, it’s more likely to encounter issues during takeoff and potentially crash if it doesn’t have enough runway to compensate.
126F is Too Hot For Planes to Take Off In
Aircraft performance is usually only impacted at a temperature of 86°F/ 30°C or higher, though this doesn’t mean a plane won’t be able to take off at such a temperature.
The exact temperature at which a plane can’t take off depends on the model.
Each plane has a maximum safe take off temperature, which is provided to the airlines by the manufacturer.
Large planes have the most tolerance for extreme heat.
For example, large planes like the Boeing 737 or Airbus A320 experience issues at 126°F/52°C.
Additional factors that impact what temperature a plane can’t take off include the airport’s elevation.
Extreme heat impacts planes more at higher elevations, since the air at higher elevations has less oxygen.
Conversely, Below -40F is Too Cold For Planes to Take Off In
Most airplanes won’t fly below -40°F/C since their fuel may freeze.
But, it’s possible for airplanes to even take off at -69°F/56°C if they have the right fuel blend.
Yet, most airlines won’t fly planes below -40°C/F because cold-resistant blends of aviation fuel are expensive, rendering many flights uneconomical.
A Lot of Flights Are Delayed or Canceled Due to Extreme Heat
Flights are often delayed or canceled because of extreme heat in hot areas.
For example, Phoenix, Arizona, is reputed for frequent heat-related flight delays and cancellations.
Climate change has also increased heat-related flight delays.
There Are Solutions to Allow Planes to Take Off in Extreme Heat
There are a few potential solutions to enable planes to take off in extreme heat.
Airlines could schedule flights earlier in the morning or later in the evening.
Such schedule changes would reduce exposure to extreme heat, but it would be extremely inconvenient for passengers who’d have to fly at less common hours.
Airports could also increase their runways to give planes more room to takeoff.
But, this solution is potentially difficult for airports because of the construction costs and logistics of increasing runway length.
Another potential solution is to use more efficient aircraft engines or reduce the number of passengers.
These solutions are the most likely to be adopted.
Extreme Heat Can Increase Turbulence
Extreme heat causes convective or thermal turbulence.
This phenomenon occurs when the sun heats the earth’s surface, causing warm air to rise above.
The rising warm air mixes with falling cool air, causing turbulence.
Generally, extreme heat causes turbulence during daytime. So, many pilots prefer flying at night or in the early day to avoid convective turbulence.
Helicopters Have No Problem Taking Off in Extreme Heat
Most helicopters can take off in extreme heat.
Like planes, helicopters also experience fewer air molecules during extreme heat, which decreases lift, but helicopters can compensate for the fewer air molecules by increasing the rotational speed of their rotor blade.
So, a helicopter may take off during extreme heat if its rotor blade can rotate fast enough.
Helicopters often reduce their cargo, the number of passengers, or fuel load to take off during extreme heat.
- Airplanes don’t take off during extreme heat because the heat reduces air density.
- A lower air density prevents planes from generating the lift they need to take off.
- Planes can compensate for the reduced lift by increasing their speed and runway time.
- But, this solution is impractical in many instances, especially if the plane is taking off from an airport at a higher elevation.
- Most airplanes have a maximum takeoff temperature determined by the manufacturer.
- Extreme heat also causes turbulence, which further reduces the viability of taking off during extreme temperatures.
- Presently, climate change has increased the number of heat-related flight cancellations.
See Also: Your Flight Disruption Survival Guide