The Dangers of Extremely High Altitude Flight: What Happens to Planes?

The world of aviation is fascinating, but flying at extremely high altitudes presents unique challenges that pilots and engineers need to be aware of. While commercial airliners can reach altitudes of up to 39,000 feet, there are limits to how high planes can safely fly.

Understanding the Basics: Lift and Stall

Planes fly because of a phenomenon known as lift. The wings are designed in a specific shape that causes the air flowing over the top surface to move faster than the air under the bottom surface. This speed difference results in higher pressure beneath the wing and lower pressure above, creating a force that lifts the aircraft into the air.

The lift generated by the wings depends largely on the amount of air flowing underneath them. At high altitudes, the air becomes thinner, meaning there is less air to generate lift. If the total lift produced by the wings is less than the weight of the plane, the plane will stall and begin to descend.

A stall occurs when the air passing over the wing no longer flows smoothly, causing the plane to lose control and fall. This is often due to the aircraft reaching an angle of attack (AoA) that is too high, disrupting the air flow over the wing and leading to a loss of lift.

Factors Limiting High-Altitude Flight

Normal aircraft are limited in their ability to operate at extremely high altitudes due to several factors:

Oxygen Starvation: Unlike rockets, which have their own oxygen supply, air-breathing engines need oxygen from the air to function. As altitude increases, the air becomes thinner, leading to oxygen starvation. Without sufficient oxygen, the engines will shut down. Lack of Lift: At very high altitudes, the air is so thin that there is insufficient lift to keep the plane in the air. This means that the plane can no longer maintain its altitude and will start to descend.

Sub-Arbitrary Space and the Atmospheric Challenge

While space is generally considered to begin at an arbitrary altitude of 300,000 feet, the atmosphere becomes dangerously thin well before this point. Below this height, pilots still face severe challenges, such as oxygen starvation, which can lead to hypoxia (lack of oxygen) and can cause pilots to blackout or pass out. Commercial aircraft are equipped with oxygen masks for passengers and crew in case of sudden loss of cabin pressure.

What Happens If an Airplane Goes Too High?

When an airplane climbs to a height where the air is too thin, several critical factors come into play:

Increased Stall Risk: As altitude increases, the stall speed decreases. Pilots must fly faster to maintain lift, but if they increase their angle of attack too much, they risk stalling the plane. Angle of Attack and Lift: The angle of attack (AoA) is the difference between the orientation of the wing and the airflow. Increasing the AoA can temporarily increase lift, but if the AoA reaches the critical angle of attack, the air flow over the wing is disrupted, causing a stall. Air Pressure and Temperature: At extreme altitudes, the air pressure is very low, and temperatures can be extremely cold. This requires special fuselage design and insulation to ensure that both the aircraft and the crew can withstand these harsh conditions.

Conclusion

While modern aircraft are remarkably capable, they face significant challenges when flying at extremely high altitudes. These challenges range from oxygen starvation and engine failure to increased stall risks and the need for special design features to maintain structural integrity. For safety reasons, it is crucial that pilots and aircraft designers understand these limitations and work to mitigate the risks associated with high-altitude flight.