Planes fly at high altitudes to have better fuel economy, escape obstacles, and have better reaction time during emergencies.

Commercial airplanes regularly fly at altitudes of 35,000 feet, but smaller planes fly at lower altitudes due to their weaker engines and often unpressurized cabins.

Private jets fly even higher than commercial planes, primarily to escape air traffic.

But, the highest flying planes are military ones, especially fighter jets and spy planes, yet even these planes can’t fly into space.

Most airplanes can fly higher than most helicopters, which can’t ascend beyond 25,000 feet. 

5 Reasons Why Planes Fly So High

Planes fly at high altitudes for these 5 primary reasons. 

Optimum Flight Conditions

Air resistance is lower at high altitudes due to the atmosphere being thinner.

Lower air resistance is preferable for aircraft since it reduces energy expenditure.

Aircraft burn more fuel to fly through more air molecules, which increases the amount of fuel consumed, and subsequently fuel costs. 

Also, the colder temperatures, around -55°C (-67 Fahrenheit), at higher altitudes improve jet engine efficiency, further reducing fuel costs.

Fuel Savings

Commercial airplanes save more fuel when flying at higher altitudes due to lower air resistance and improved engine efficiency.

Commercial aircraft normally fly between 32,000 and 38,000 feet, with an altitude of 35,000 feet considered the ideal for reducing fuel expenditure. 

Avoid Turbulence and Harsh Weather Conditions

Airplanes avoid turbulence and bad weather conditions at higher altitudes since they fly above the clouds and the air is more stable at higher altitudes.

Planes can fly through clouds and storms, but they experience turbulence and potential wear and damage to certain components by doing so.

So, it’s always better for planes to avoid turbulence and bad weather by flying at higher altitudes. 

Obstacle Avoidance

Airplanes also fly at high altitudes to completely avoid any obstacles, both natural and man-made.

At 35,000 feet, airplanes don’t encounter any man-made structures and are very unlikely to encounter birds, which can sometimes lead to disastrous consequences if struck.

So, flying at higher altitudes is safer for airplanes.

Most international aviation authorities even forbid planes from flying below 1,000 feet except during emergencies. 

Another benefit of high altitude flight is that planes don’t cause noise pollution to the ground.

Airplanes are extremely noisy and loud, so flying at higher altitudes saves people on the ground from noise pollution.

Safety Cushion

Another benefit of high altitude flight is increased reaction time during emergencies.

For example, if the aircraft’s engines fail, the flight crew has a better chance of implementing safety procedures at 35,000 feet than at 3,500 feet due to the increased time before reaching the ground. 

What Altitude Do Planes Fly At?

Generally, small planes fly at the lowest altitudes, while commercial airliners and private jets fly at the highest altitudes.

Military planes fly at different altitudes depending on the plane’s design and purpose. 

Small Planes

Most small planes fly between 2,000 and 10,000 feet.

Most small planes have piston engines that don’t operate well in thinner air.

Pilots of smaller aircraft, such as private pilots, also avoid higher altitudes since most small planes don’t have oxygen providing equipment, which is necessary for flying at high altitudes. 

Small planes also generally fly short distances, so small plane pilots avoid high altitudes to reduce the time spent climbing and descending.  

Private Jets

Many private planes can fly as high as 45,000 feet, but most cruise at only 41,000 feet.

Private jet fly at higher altitudes than commercial airliners to avoid air traffic and fly faster, more direct routes to their destinations.

Private jetare also more fuel efficient at higher altitudes, but the optimum flying altitude for a private jet depends on its route and destination. 

Commercial Airliners

Most commercial airplanes fly between altitudes of 33,000 to 42,000 feet, with 35,000 feet considered ideal for most planes, though the highest airliner can reach 45,000 feet.

Commercial planes fly at these altitudes since they’re ideal for fuel efficiency, obstacle avoidance, and bad weather avoidance. 

Military Planes

A military plane’s flying altitude depends on its role and model.

Most fighter jets can fly between an altitude of 45,000 to 51,000 feet. Some, like the F-22 Raptor, can fly as high as 65,000 feet through vertical ascension. 

Military spy or reconnaissance planes, like the U2, can fly even higher at 70,000 feet.

These aircraft fly at higher altitudes to avoid detection and cover larger areas during photographic or video reconnaissance. 

In contrast, Cargo planes and CAS (Close Air Support Aircraft) fly at lower altitudes.

Cargo planes, like the C-130, usually fly at an altitude of 23,000 feet because of their heavy payload. CAS aircraft like the A-10 operate under a height of 1,000 feet to assist ground forces in combat conditions.

Why Planes Fly At Different Altitudes

Different planes have different optimum cruising altitudes and different designs, which are optimized for different altitudes.

Most older commercial aircraft are designed to fly at lower altitudes, but newer commercial aircraft can fly at higher altitudes.

Sometimes, the altitude a plane flies at also depends on procedures of the airspace it is flying in. 

Planes Should Never Fly Too High

If commercial planes fly too high, they reach a point called the “Coffin Corner“.

A plane immediately begins to descend after reaching its Coffin Corner. 

This phenomenon is caused by the air being too thin for enough air to pass through the plane’s engine for it to produce enough thrust to continue climbing.

The Coffin Corner for most commercial planes is between 40,000 to 45,000 feet, but it can be higher or lower depending on factors like the plane’s weight and design. 

Helicopters Fly A Lot Lower

Turbine engine helicopters can reach 25,000 feet in altitude, but they can’t hover at that height.

The average civilian helicopter, like the R22, can only fly as high as 12,000 feet.

But, the exact height a helicopter can fly depends on its engine, model, weight, and size. 

In conclusion:

  • Planes fly at high altitudes, between 30,000 to 35,000 feet, because it’s optimal for them to do so.
  • Planes encounter fewer obstacles, have better fuel economy, and increase reaction time during emergencies at higher altitudes.
  • Generally, small planes rise to the lowest altitudes, but commercial and private planes fly at much higher altitudes.
  • Private planes fly at higher altitudes than commercial planes to escape air traffic.
  • Military aircraft, especially spy planes and fighter jets, can fly at the higher altitudes than all other planes.

Helen Krasner holds a PPL(A), with 15 years experience flying fixed-wing aircraft; a PPL(H), with 13 years experience flying helicopters; and a CPL(H), Helicopter Instructor Rating, with 12 years working as a helicopter instructor.

Helen is an accomplished aviation writer with 12 years of experience, having authored several books and published numerous articles while also serving as the Editor of the BWPA (British Women Pilots Association) newsletter, with her excellent work having been recognized with her nomination of the “Aviation Journalist of the Year” award.

Helen has won the “Dawn to Dusk” International Flying Competition, along with the best all-female competitors, three times with her copilot.