Ever wonder why airplanes stall at high altitudes? Most commercial airliners have a cruising altitude of about 30,000 feet. The air is thinner at high altitudes such as this, so commercial airliners burn less fuel and experience less turbulence. If they fly too high, however, they may stall.
Stalls Explained
A stall is a phenomenon in which an airplane fails to generate a sufficient amount of lift. It occurs when the airplane’s angle of attack exceeds a critical value.
All airplanes have an angle of attack during flight. It’s the angle between the chord line of the airplane’s wings and the oncoming air. If this angle exceeds a certain value, the airplane will experience a stall. It will fail to generate enough lift to keep it in the air, resulting in a loss of altitude until the pilot is able to recover from the stall.
Stalls Can Occur at Any Altitude
It’s a common misconception that stalls can only occur at high altitudes. Since they involve an excessively high angle of attack, stalls can occur at any altitude.
Low-altitude stalls, in fact, are often considered more problematic because pilots have less time to recover from them. When a stall occurs, the pilot must correct the airplane’s angle of attack so that it will generate a sufficient amount of lift. The lower the airplane’s altitude at the time of the stall, the less time the pilot will have to react accordingly.
Why High-Altitude Stalls Are Common
While stalls can occur at any altitude, they are common at high altitudes. This is because airplanes must fly faster at high altitudes to prevent stalls from occurring.
As previously mentioned, the air is less dense at high altitudes than at low altitudes. Commercial airliners and other airplanes leverage the “thin” air at high altitudes to conserve fuel.
How Pilots Prevent Stalls
There are several things pilots can do to prevent stalls, one of which is to monitor the airplane’s angle of attack. Stalls are characterized by an excessively high angle of attack. Fortunately, most airplanes are equipped with an angle of attack indicator that, as the name suggests, reveals the airplane’s angle of attack.
Many airplanes are also equipped with stall protection systems. Stall protection systems consist of stick shakers or pushers that provide tactile feedback if the airplane is about to experience a stall. They essentially alert the pilot so that he or she can take corrective action.
