Did you ever watch a huge airplane such as an A380 and wonder how this huge machine weighing almost 600 tons can get off the ground and fly? And once you stopped trying to work that out, did you then begin to wonder how high an airplane will fly after it has taken off and reached its cruising altitude?
Modern flight is truly an amazing feat and today’s aircraft have reached some almost unbelievable flying achievements. When you see a modern jet aircraft high above it’s sometimes hard to believe that the history of modern powered flight only goes back just 100 years.
In this article, I’m going to provide some details on how high airplanes fly and show you the differences between a variety of different aircraft types. First of all, I’ll explain the basics of aeronautics and how aircraft fly in a simple and easy-to-understand way. After that, I’ll look into the reasons why aircraft fly at high altitudes and then delve into some details of the flying altitudes of different categories of aircraft such as commercial airliners, private jets, light aircraft, and military jets.
The Science of Flight – A Basic Overview
Not surprisingly the keys to flight are an aircraft’s wings. But wings are only part of the story. The science of flight is rooted in Newton’s Third Law of Motion and how there is a reaction to each action. There are four forces that act on an airplane in flight:
- Lift supports an airplane in flight. Lift is the opposite force to gravity and is generated when air flows smoothly over a wing. Most wings have a curved upper surface and a flat lower surface creating a cross-section shape that is called an airfoil. As the wing cuts through the air, the air flows over, as well as under, the wing, and an area of low pressure is created above the wing, acting to pull the airplane upwards.
- Weight is caused by gravity and acts to pull the airplane toward the ground. When the lift created by the wings exceeds gravity, the airplane will leave the ground and climb and continue to fly.
- Thrust is the force that moves an airplane forward. Generally, it is created with a propeller or by jet engines. Air is pulled into the engines and then pushed out in the opposite direction.
- Drag is the force that acts opposite to the direction of motion. It tends to slow an object and is caused by friction and differences in air pressure. If you put your hand out of a moving car window you will feel it being pulled back – this is drag.
The way the four forces act on the airplane make it behave differently. Each force has an opposite force that works against it. Lift works opposite weight (gravity). Thrust is the opposite of drag. When the forces are balanced, an airplane will fly in a level direction.
An airplane will go up if the forces of lift and thrust are more than gravity and drag. If gravity and drag are larger than lift and thrust, the airplane will go down.
Why Do Aircraft Fly So High?
When flying with an airline you’ve probably heard one of the flight crew announce that you’ll be “flying at 35,000 feet.” That’s pretty high; more than 6 miles high in fact! The key reasons are as follows:
- Fuel efficiency: Aircraft are designed to operate more efficiently at high altitudes where the air is thinner so there is less drag on the aircraft, resulting in less fuel burn. However, there is a limit to this. Aircraft engines need oxygen, and the amount of oxygen in the air decreases with altitude. If the altitude is too much, then the jet engines will produce less thrust, and the lift produced by the wings will also decrease. Stress forces on the fuselage produced by pressure imbalances between the artificial pressure inside the aircraft and the low-pressure air outside are also a key consideration. So, the optimal flying altitude is a balance between air density and oxygen levels, and each aircraft engine will be designed with an optimal altitude in mind.
- Hazard avoidance: Flying at high altitudes means that aircraft can avoid other airborne traffic such as light aircraft, helicopters, drones, and birds.
- Avoiding bad weather and turbulence: Commercial aircraft usually fly above the troposphere in order to avoid storms, strong winds, and other weather events. The troposphere extends up to around 36,000 feet. Turbulence is less common, but not completely absent at high altitudes too.
- Safety and separation: Aircraft are separated both vertically and horizontally by air traffic control (ATC) to avoid collisions. There’s a well-established ATC rule that commercial aircraft will cruise eastbound at so-called ‘odd’ altitudes in increments of 2,000 feet e.g. 35,000 feet and 37,000 feet, whereas a westbound flight will cruise at even-numbered altitudes e.g. 34,000 feet and 36,000 feet. This means that an aircraft moving towards another aircraft will be separated vertically.
- Emergency response: Flying at high altitudes gives the flight crew more time to react and decide on corrective action in the unlikely event of an emergency.
When it comes to altitude there is one key aircraft design feature that makes all the difference – cabin pressurization which provides a comfortable, and frankly survivable, environment for passengers and crew at high altitudes. As a general rule, any aircraft flying above 10,000 feet needs to be pressurized. This is one of the key reasons that light aircraft (which are not pressurized) fly at much lower altitudes than commercial airliners.
How High Do Aircraft Fly? A Look at Maximum Altitudes…
Now that we’ve grasped some basic concepts, let’s take a look at the maximum design altitude that an aircraft is designed to fly at, known as the service ceiling, as a way to compare different types of aircraft. Just keep in mind that aircraft rarely fly at their service ceilings.
The EAA’s definition of service ceiling is the height above sea level at which an aircraft with a normal-rated load “is unable to climb faster than 100 feet per minute under standard air conditions.” In other words, the service ceiling is the maximum density altitude an airliner can reach according to its design. Service ceilings tend to be around 40,000 feet for commercial airliners. However, commercial aircraft are more likely to cruise at an altitude of around 35,000 feet.
Commercial Airliners
Modern commercial airliners tend to have service ceilings generally up to around 43,000 feet. That said, as mentioned above, more often than not, airliners will cruise at around 35,000 feet, give or take a couple thousand feet.
The table below shows these parameters for the most common Boeing, Airbus, and other commercial aircraft:
| Aircraft | Service Ceiling |
| Boeing | |
| 737 Original/ Classic | 37,000ft |
| 737NG, 737MAX | 41,000ft |
| 747-100, -200, -300, -400 | 45,100ft |
| 747-8 | 43,100ft |
| 757 family | 42,000ft |
| 767-100, -200, -300 | 43,100ft |
| 767-400 | 43,100ft |
| 777 family, | 43,100ft |
| 787-8 | 43,100ft |
| 787-9 | |
| 787-10 | 41,100ft |
| Airbus | |
| A220 | 41,000ft |
| A300 | 40,000ft |
| A310 | 41,000ft |
| A318 | 39,800ft |
| A320ceo family | 39,100 – 41,000ft |
| A320neo family | 39,100 – 39,800ft |
| A330-family | 41,450ft |
| A340 family | 41,450ft |
| A350-900 | 43,100ft |
| A350-1000 | 41,450ft |
| A380 | 43,100ft |
| Other | |
| Embraer E-Jet/ E2 | 41,000ft |
| Bombardier CRJ | 41,000ft |
Boeing
The 787-8 and 787-9 Dreamliners have a service ceiling of 43,100 feet, whereas the stretched 787-10 has a ceiling that is a little lower at 41,100 feet. The older 747 variants have very high service ceilings exceeding 45,000 feet. The more modern 747-8, has a service ceiling of 43,100 feet. The variants in the 767 and 777 families share the same service ceiling of 43,100 feet.
For the Boeing narrowbodies, the 737NG and 737MAX have certified service ceilings of up to 41,000 feet, while the older 737 versions (Original and Classic) are certified only to 37,000 feet. The 757 family has a service ceiling of 42,000 feet.
Airbus
The A320neo aircraft family (A319neo, A320, and A321neo) are certified to fly up to a range between 39,100 and 39,800 feet. However, the aircraft in the A320ceo family have service ceilings of between 39,100 and 41,000 feet. The A220 also offers a service ceiling of 41,000 feet. The A318 has a maximum ceiling of 39,800 feet.
Airbus widebodies such as the A380 and the A350 have service ceilings of up to around 43,000 feet. Although the A350-1000 has a ceiling that is a little lower at 41,450 feet. The A330 and A340 have maximum service ceilings of 41,450 feet, whilst the A300 and A310 have service ceilings of 40,000 feet and 41,000 feet respectively.
Embraer and Bombardier
The Embraer E-Jet and E2 series aircraft and the Bombardier jets in the CRJ series have service ceilings of 41,000 feet.
Concorde
We need to talk about Concorde even though it is no longer operational. Concorde was rated to fly up to 60,000 feet.
With its very powerful engines, Concorde was able to ascend much more rapidly compared to subsonic airliners, and therefore it could reach its high cruising altitude relatively quickly. Also, Concorde’s engines were specifically designed to cope with high-altitude air with low oxygen concentrations.
The sleek design of Concorde resulted in minimal levels of drag and the delta wing configuration meant that this aircraft was less reliant on wing lift to stay in the air compared to subsonic airliners with their more traditional wing design.
One very interesting fact is that Concorde’s windows were very small. If a window blew out, Concorde’s air compression system could actively compensate by pumping air into the cabin faster than it could escape, giving the flight crew sufficient time to complete an emergency descent.
Private Jets
Many private jets have higher service ceilings than commercial airliners, typically between 45,000 and 51,000 feet, but usually fly at an altitude of around 41,000 feet. Why is this? There are four main reasons:
- To avoid commercial air traffic, typically flying 35,000 and 40,000 feet
- To avoid bad weather and turbulence
- Superior climb ability due to lighter weight and relatively more powerful engines compared to commercial airliners allowing private jets to climb faster
- Improved performance and efficiency by flying through less dense air
The private jets with the highest service ceiling of 51,000 feet include the following:
- Bombardier Global 6000
- Dassault Falcon 5X
- Gulfstream G650
Light Aircraft
Most private light aircraft typically fly at altitudes between 2,000 and 6,000 feet, although they are capable of flying at higher altitudes. For example, the Cessna 172 has a service ceiling of 13,500 feet.
Light aircraft fly at much lower altitudes than commercial airlines for the following reasons:
- They are not pressurized
- Their engines are not that powerful and so they operate at relatively low speeds. If you combine this with the fact that they tend to make relatively short flights it does not make sense for these aircraft to spend a lot of time ascending and descending to higher altitudes
- Air traffic control and licensing requirements mean that these aircraft are restricted to lower levels as their pilots are often trained only to fly under Visual Flight Rules (VFR) where good visibility of the ground is needed
Military Aircraft
Military aircraft typically fly higher than 50,000 feet.
American aircraft company Lockheed seems to be the master at developing very high-altitude military aircraft. Examples (excluding proposals, prototypes, demonstrators, and drones) of military aircraft with service ceilings above 65,000 feet include the following:
| Aircraft | Service Ceiling |
| Lockheed A-12 (Archangel 12) | 95,144ft |
| Lockheed YF-12 | 89,895ft |
| Lockheed SR-71 (Blackbird) | 85,000ft |
| Lockheed Martin U-2 Dragon Lady | 84,974ft |
| Dassault MD.117-33 | 80,052ft |
| Mikoyan-Gurevich MiG 25 (Foxbat) | 80,052ft |
| Myashishchev M-55 (Mystic) | 70,538ft |
| Mikoyan MiG-31 (Foxhound) | 67,651ft |
| Shenyang (AVIC) J-8/J-8II (Finback) | 66,273ft |
| General Dynamics F-111 Aardvark | 65,954ft |
| Dassault Mirage F-1 | 65,643ft |
| Chengdu (AVIC) J-10 (Vigorous Dragon) | 65,617ft |
| Dassault Mirage 4000/Mirage III/Mirage IV | 65,617ft |
| General Dynamics F-111K Aardvark | 65,617ft |
| HAL Sukhoi PMF/PGFA | 65,617ft |
| Mitsubishi F-15J (Peace Eagle) | 65,617ft |
| Mitsubishi F-X | 65,617ft |
| Saab J-35 Draken | 65,617ft |
| Sukhoi Su-15 (Flagon) | 65,617ft |
| Sukhoi Su-17 (Felon) | 65,617ft |
| TAI Kaan (TF-X/F-X) | 65,617ft |
| Tupolev Tu-28 | 65,617ft |
| Boeing (McDonnell Douglas) F-15 Eagle | 65,010ft |
When looking at military aircraft service ceilings there is a number that crops up time and time again in non-US aircraft – 65,617 feet; this is equivalent to 20,000m.
Summary
So, in descending order the aircraft categories ranked by service ceiling are as follows:
- Military aircraft
- Private jets
- Commercial airliners
- Light aircraft
There are some exceptions to this. Notably, Concorde was able to fly at altitudes of up to 60,000 feet, that’s typically where you might find some military aircraft.
It seems that there is a well-defined system and order, as you would expect, and this relates not just to the function of each aircraft but also to the speed and ability of each aircraft type to ascend and descend quickly to make flying at high altitude worth the effort.
