HAVE you ever wondered how high the plane you're travelling in really goes?
There's a sweet spot in the sky where planes can cover huge distances very quickly but too high and they can run into serious problems. Here's what we know.
How high do planes fly?
Commercial planes fly between 35,000 and 42,000 feet- which is upwards of 6.6 miles up in the air.
But if they go too high it wouldn’t be good for anyone on board.
According to the Smithsonian National Air And Space Museum, the plane would run into difficulty because the air becomes thinner the higher you go in the atmosphere.
They said: "If a plane flies higher than the altitude it was designed to fly it, it will be difficult to create enough lift to keep the plane up.
"Lift is created by differences in air pressure.
"Planes can't just keep going up and up – at some point, the air will be too thin for them to fly."
Why do planes have to fly so high?
Aeroplanes fly high to improve fuel efficiency and travel faster.
A jet engine operates more efficiently at higher altitude where the air is much thinner, allowing an aircraft to travel faster whilst at the same time, burning less fuel.
Flying above 30,000ft also has the benefit of allowing the aeroplane to fly above most weather systems making it more comfortable for the passengers.
At lower altitudes, the engines can only be run at maximum thrust during take-off or perhaps the climb or else the aircraft would quickly exceed its maximum speed limitation.
If you tried to fly straight and level at 10,000ft with more than 70 per cent thrust set, you would quickly overspeed most commercial jet aircraft. At 70 per cent thrust, the engine isn’t running very efficiently.
As the aircraft climbs in altitude, the jet engines produces less thrust (as the air is thinner), but it maintains a high compression ratio and thermal efficiency.
As the air is thinner, the plane is able to achieve a much higher speed than lower down, meaning the aircraft travels much faster whilst the engines burn less fuel.
What is the highest a plane can fly?
But too high and there is insufficient oxygen to fuel the engines.
Peter Wheeler, a pilot, said on Quora: "Most aircraft are limited by engine power.
"The air is less dense at altitude, so the engine can suck in less and less air per second as it goes higher and at some point the engine can no longer develop sufficient power to climb."
Back in 2004, Pinnacle Airlines flight 3701 was destroyed after flying to 41,000 feet, with two members of crew on board at the time.
Retired rescue helicopter pilot and aviation safety contractor Tom Farrier revealed: “Both engines failed, the crew couldn't get them restarted, and the aircraft crashed and was destroyed.”
Most commercial aircraft are approved to fly at a maximum of around 42,000 feet. This maximum is also known as a ‘service ceiling.’
For the double-decker Airbus A380 ‘superjumbo’ quadjet, this ceiling is 43,000 feet.
Meanwhile, for the Boeing 787-8 and -9 ‘the Dreamliner,’ it is 43,100 feet. The stretched 787-10 comes in a little lower, at 41,100 feet.
How fast do planes fly?
A typical commercial passenger jet cruises at a speed of around 460 to 575 mph. Generally speaking, the higher the aircraft flies, the faster it can travel.
It cruises at this speed at a height of about 36,000ft. This high speed can only be achieved at high altitude.
The fastest passenger plane was Concorde in 1996 which reached 1,249 mph.
The fastest fighter jet plane reached 4,519 mph in 1967, the North American X-15 rocket plane.
Sonic booms are created when aircraft travel faster the the speed of sound, about 761 mph.
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