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Can it be too hot to fly a plane? A pilot explains

Warmer heat waves are sweeping across Europe and North America. The U.K.’s recent record temperature of 100 F, a number set to continue to rise over the next few days, has taken place in an often gra

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Europe and North America are experiencing record high temperatures this week. In the United States, cities in Texas, Oklahoma, Colorado, and Arkansas have already seen record high temperatures. In the frequently drab and gloomy United Kingdom, the temperature is expected to reach a record 100 F.

These temperatures can be quite challenging to tolerate for individuals without air conditioning. It gets more stressful to get to work, and it could be very challenging to get to sleep at night. Overall, I wouldn’t call it a nice experience.

Hot days not only affect how we work and rest, but they also have an impact on the airplanes we fly in.

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Post about air density

The expression “hot air rises” is one that we’ve all heard, but what does it actually mean and how does it impact your flight?

The majority of the particles in the air around us are made up of 78 percent nitrogen, 21 percent oxygen, and 1 percent of different other gasses (such as carbon dioxide and water vapor). These air molecules occupy all of the available space as they bounce around the area like balls in a slot machine. The atmosphere is what you see here.

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The atoms in these molecules become more excited and move about more as the temperature rises. The more they travel and distance themselves from one another as they heat up, the less thick the air becomes. On the other hand, as the temperature drops, the atoms become less excited and the air becomes denser, causing it to fall lower.

On a typical day, the temperature of that air mass rises as the sun warms the ground and the air above it. As a result, the air molecules travel more quickly and climb higher into the sky, lowering air pressure as the density rises. The hot air “thins out,” rising as a result.

The molecules become less agitated and sink back down toward the earth as the hottest portion of the day ends and the air starts to cool, increasing the density and, as a result, the air pressure. The same volume of air is now significantly heavier than it was earlier in the day.

A short review of aircraft flight

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Why then does air density affect aircraft? Contrary to popular opinion, airplanes actually fly because of their wings, not their engines.

There is a differential in pressure between the lower and top surfaces of the wings as air passes over them. (The pressure is higher underneath and lower on top.) This pressure difference is what causes lift. The airplane may take off and fly when the lift produced by the wings exceeds the weight of the vehicle.

For those of you who enjoy arithmetic, the lift formula is…

As a result, the wing area, air density, and air speed over the wing all affect how much lift is generated.

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The purpose of the engines is to propel the airplane forward so that air can flow over the wings. The engines propel the airplane forward during the takeoff run, forcing air over the wings. Once the aircraft achieves a certain speed, there will be enough lift for it to take off since the amount of lift generated is partially governed by how quickly air flows over the wings.

Because of this, even if both engines fail, an aircraft won’t just drop out of the sky. The pilots would simply lower the nose slightly and use gravity to keep air flowing over the wings, producing lift, if that very unlikely occurrence were to occur. An airplane at 43,000 feet can glide for around 130 miles, giving a glide ratio of nearly 3 miles for every 1,000 feet above the ground.

Air density’s impact on aircraft

We can now start to comprehend how the air temperature influences aircraft flight since we have a basic understanding of how they operate.

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As I previously stated, a variety of variables, including the speed and density of the air over the wing, affect how much lift is produced.

The difficulties that pilots face when landing at hot and mountainous airports

We have agreed that colder weather results in denser air, which causes molecules to fall lower and clump closer together. The numerous air molecules that are travelling over the surface of the wing as this air passes over it create the ideal circumstances for lift.

On a hot day, the air is significantly less dense. Because there are a lot fewer air molecules on the surface of the wing when that hot air passes over it, less lift is produced.

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Due to this distinction, pilots prefer to fly on cool, dense air days as opposed to hot, less dense air days. In addition to producing higher lift at a given speed, the wings also improve the aircraft’s ability to “bite” into the air and respond to control inputs.

What if it becomes too warm?

We’ve noticed that wings have a harder time producing lift on hot days than they do on chilly days. The performance of an airplane is significantly impacted by temperatures of 86°F and above.

So what can we do if the air density drops but we still want the lift produced to remain constant? Delaying the flight till the air temperature drops is one option. Because of this, many really long-distance flights take off late at night when the air is at its coldest.

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It’s not ideal, though, to postpone a flight because of a high temperature. The area of the wing and the speed of the air over the wing are the other two factors in the formula, keeping this in mind.

enlarge the wing

The first choice is to increase the wing’s size. How can you just make it larger? This might sound like a weird idea, but it’s not as crazy as you might think.

A plane’s wing appears fairly smooth and sleek when you first board and can see it. However, as soon as the engines begin to run, you hear a loud whirring sound from beneath you, and the surfaces on the leading and trailing edges of the wing begin to move outward.

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We may increase the aerodynamic surface area of the wing and hence get a greater result for our lift formula by extending the flaps and leading edge slats. Most commercial aircraft set their flaps to about a 5-degree extension for takeoff.

They can reach a maximum angle of about 30 degrees, which is employed for landings. One approach is to utilize a higher flap setting and increase the area of the wing because doing so will improve lift.

This is a solution, however it’s crucial to remember that the more flap you apply, the more drag enters the picture.

The aerodynamic force that slows down an object is called drag. An object has more drag the more it is “hanging out” into the wind. This explains why fighter jets and sports automobiles have low, streamlined profiles.

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Related: Your flight did not reach supersonic speed. It was merely a really swift wind.

There comes a point where the drag created becomes a bigger issue if we utilize more flap to increase the surface area of the wing. The amount of lift produced decreases as drag increases because the quicker the plane must fly to overcome the added force.

Move swiftly

Although it does work, using more force to produce more lift is incredibly inefficient. The alternative is to only quicken the airflow across the wing. There are two methods for doing this.

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The first step is to launch into a powerful headwind. Even though an aircraft is immobile compared to the ground, it will get airborne if it needs an airspeed of 100 mph over the wings and is angled into a 100 mph wind.

The little airplane in the video below can take off with very little air across its wings. So little, in fact, that stormy weather can produce winds forceful enough to satisfy these requirements. The outcome? Any unanchored aircraft can swiftly move to a different location.

But since most commercial aircraft require airspeeds of about 180 mph to take flight and wind alone can only provide up to 30 mph of lift, the remaining 150 mph must be produced by the engines.

We don’t usually take off with our engines at full power, which is another little-known truth. This is due to the fact that it consumes a lot of fuel, necessitates more maintenance, and is noisy for those who live and work nearby the airport. As a result, we strive to take off with the least amount of engine power that is yet safe.

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To do this, we determine before every departure just how much engine power we require by taking into account all the variables, including air temperature, air pressure, wind speed, and aircraft weight. We can then determine how much engine power will be required to accomplish our takeoff speed with the runway length available by adding the length of the runway that is accessible to us.

We can only increase engine power if we need to raise the speed because we are no longer able to extend the wing area and the air density is too low due to the runway’s set length. But there can be a time when we are operating at maximum power and the runway isn’t long enough for us to reach takeoff speed before it expires.

Because of this, airports in popular locations like Dubai and Singapore have extraordinarily long runways. When periods of extraordinarily high temperatures occur at airports with shorter runways, which are adequate for typical weather, the runway length can suddenly become a limiting factor.

when there is insufficient runway

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Things really start to get difficult once we get to this point. Due to heavy drag, we are unable to increase the wing size, and the short runway prevents us from moving any quicker. Given that these are the only variables in our lift formula, it would appear that we would be stuck. There is one more thing we can alter, though: the amount of lift necessary to take off.

As was previously mentioned, an aircraft can only fly when its weight is greater than the lift produced by its wings. The only option to still take off if we run out of lift is to lighten the load on the airplane to a level that will allow us to safely take off.

The one factor that cannot be altered while loading an airplane is its empty weight. We need to search for the variables once more. There are four of these: the quantity of gasoline we load, the quantity of people we transport, the quantity of bags we transport, and the quantity of goods we transport.

Cargo will be the first to depart because it may be loaded onto a later flight with little to no hardship to the passenger. The fuel figure is the next thing we’ll aim to decrease, but naturally, there is a limit to how much we can cut this.

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We might consider the amount of fuel we’ll need to taxi to the runway or the amount of backup fuel we have in case of unforeseen routings or heights. Even on a long-haul journey, we only realistically save a few hundred kg of weight by doing this.

The last factor is when airlines seriously alienate their patrons by dumping them or leaving their bags behind.

Related: Approaching the runway: How pilots navigate safely to the ground in all weather conditions

No airline wants to leave travelers or their luggage unattended, let’s be clear about that. Although the pilots are aware that the aircraft is excessively heavy for the current environmental conditions, they will under no circumstances risk taking off.

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The only choices are to cancel the flight or send some of the passengers and/or luggage on another flight.

To sum up

High temperatures have an impact on how we work and sleep, as well as how airplanes fly. The performance of the lift-generating wings is decreased as the temperature rises due to a change in air density. There are workarounds for pilots to get around this, but only so far.

If it gets so hot that the pilots are unable to make any further adjustments to their takeoff performance, the only way to fly safely is to either unload people and luggage or cancel the flight.

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It is our responsibility to keep everyone on board our aircraft safe, even though this is far from ideal. This occasionally requires taking drastic measures.

Emirates provided the image for this post.

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