Considering the temperature range in which planes can fly, you might think the extreme heat wouldn’t put much stress on a modern aircraft. But extreme heat can have a big impact on an aircraft’s ability to operate safely and efficiently. Therefore, extreme heat is a risk that many airlines must manage and mitigate.
Extreme heat can push back the safe environmental envelope of an aircraft
Modern airplanes have what is called an environmental envelope (which includes a maximum static air temperature) in which they can fly safely. There was a well-reported incident in 2017 in Phoenix, Arizona, when several Bombardier CRJ flights were canceled because the outside air temperature was on average 49 ° C – above operating temperature. maximum allowable ambient of this aircraft.
Extreme heat is more and more common. With acres of asphalt and concrete absorbing and reflecting sunlight, airports can become temperature hot spots. Add a little wind, and it can turn out to be a volatile mixture.
Extreme heat can have a significant impact on an aircraft’s flight ability. High soil temperatures reduce air density, especially in countries with a dry climate. Airplanes need lift to take off, and lift is affected by the density of the surrounding air.
When the air density is low, planes must move faster on the runway to produce enough lift to take off. This is now necessarily a problem if you are in a lightly loaded A220 and riding a track longer than three kilometers. But if you’re in a heavily loaded Boeing 777, you might run out of runway.
Extreme humid heat can be as problematic as extreme dry heat.
It is the pilot‘s job to calculate this risk and, if it exists, to mitigate the risk. This can be achieved by reducing the weight of the aircraft – it is best to remove passengers and / or cargo. Besides the downside, it comes at an economic cost to the airline.
In equatorial regions of the world, where it is generally hot and humid, the air density may be higher, but extreme heat can produce other types of hazards. Convective cumulonimbus clouds and storms are byproducts of extreme heat in humid climates, and both are hazards to any aircraft.
Extreme heat also has an impact on aircraft engines. The extreme heat tolerance of an engine varies depending on the type and stage of flight, but there is normally a time limit attached. Sitting on the tarmac of a hot airport, it is possible that an engine will reach its maximum operating limits before producing the necessary thrust for take-off. Extreme heat can also have a negative impact on the performance of an aircraft’s canopy.
Then you have a myriad of other potential issues. Extreme heat can potentially cause overheating of brake components, air bleeder systems and electronic equipment. The air conditioning in the cabin may fail.
The risk of extreme heat can be mitigated
What is the solution ? Stop flying to hot climate airports? Building longer tracks? Neither of these options is viable. Experts suggest mitigation measures. Leaving flaps and louvers partially deployed on some types of aircraft can increase airflow and help combat temperature rises. Ventilating the aircraft on the ground can help reduce temperatures.
Then there are logistical solutions: fly heavier planes during the cooler parts of the day and lightly load planes when extreme heat is expected. Other experts suggest adjusting the flight times. Of course, this is all easier said than done. Operating an airline is a complex business and learning to handle extreme heat scenarios is only part of it.