Aviation Trivia: Know why Aeroplanes fly at heights more than 30,000 feet

The passenger aeroplanes cruise at the height of 30,000 to 42,000 feet above sea level. Have you ever wondered why? To answer the question, multiple factors come into play. Factors like air density, air pressure and others. Here we have explained why it is ideal for the aircraft to cruise at such heights. To give you a perspective of the height, the highest point on earth is Mount Everest is 8,848.86 m (around 29.031 feet) in December 2020, as certified by the Foreign Ministers of Nepal and China.

The relation between height, air pressure and flight

Moving away from the earth's surface, the density of the air decreases proportionately. It is simply because the earth's gravity pulls the air molecules closer to the earth's surface. This means that with increasing height, there are fewer molecules of air.

Reduced air pressure means less oxygen in the air for breathing, which is why planes are pressured to compensate for the loss of air pressure at high altitudes. Everyone knows that if the plane loses pressurisation for any reason, an oxygen mask will be lowered from above your head.

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Regarding flight, the aviators choose to fly high because at these altitudes, because of the lower air density, the aircraft has to face lesser air resistance, making it easier to fly. This can make the aircraft go faster while burning comparatively lesser fuel making it more economical.

Modern jet plane engines, known as turbofans, are most efficient when flown at high altitudes. When jet engines operate at their maximum RPM or exhaust temperature limits, they are more efficient. Because the air becomes thinner as the plane rises in altitude, the engines produce less thrust. This implies the plane can go significantly quicker while consuming less gasoline.

The relation between height, weather and flight

The weather changes at such great heights are minimal because of the decreased pressure changes, which makes the flight much more comfortable for the passengers. It is essential to avoid extreme weather during a flight because of the added turbulence, which at times can be dangerous.

Avoiding hazards and traffic

Flying at such high speed has its downsides. You must have heard of bird strikes damaging the plane's windshield or other parts, leading to severe accidents. Such situations can be avoided at higher altitudes. Coming to the traffic, it is to be noted that there are other means of aircraft like helicopters, drones or other light aircraft which contribute to the air traffic but are incapable of flying at higher altitudes.