Aircraft stalls are extremely dangerous since they can cause a plane to crash.
But what causes an aircraft to stall?
An aircraft stalls when it exceeds its critical angle of attack, the angle at which it generates maximum lift.
Thankfully, aircraft stalls are relatively uncommon, especially among commercial airplanes.
If a plane stalls, the pilot will attempt to reverse the stall before the plane crashes. A pilot will do this by reducing the plane’s pitch, which reduces its angle of attack and increases lift.
A plane stalls when its airfoils that are designed to produce lift are suddenly reduced because the plane’s critical angle of attack is reached or exceeded.
When the plane’s angle of attack exceeds this value, it stops producing as much lift.
A plane’s critical angle of attack is the angle where it produces maximum lift.
Most planes have a critical angle of attack of 15°. Upon exceeding this angle, airflow over the plane is insufficient to generate lift.
As a result, the plane stalls.
What Happens When an Aircraft Stalls
When an aircraft stalls, it no longer has enough lift to stay airborne. The aircraft falls as a result unless corrected by the pilot.
During a stall, the pilot experiences sluggish plane controls.
If one of the plane’s wings stalls before the other, the plane can roll to one side.
How an Aircraft Stalling Differs from a Car Stalling
A plane stalls because it’s not generating enough lift to stay in the air.
A car stalls because its engine has stopped working due to multiple possible reasons, including mechanical failure.
A car stall is also dangerous, but it’s easier to handle.
If a car stalls, the driver should just park their car on the side of the road.
In contrast, an aircraft stall could lead the plane to crash if not corrected.
Why it’s Dangerous for an Aircraft to Stall
It’s dangerous for an aircraft to stall because the plane’s wings lose their intended purpose.
The wings no longer generate the lift needed to keep the plane in the air.
So an aircraft stall leads to a plane crashing unless its stall is corrected.
A nose-pitching down tendency where the stall occurs
Aircraft Can Recover From a Stall
If a pilot notices a stall early, they may recover using the following 5 steps:
1. Disconnect the autopilot and autothrottle
The pilot needs to disconnect the autopilot and autothrottle to take manual control of the plane.
2. Nose-down pitch control
The pilot will reduce pitch control to reduce the plane’s angle of attack.
Reducing the angle of attack will increase airflow over the plane to generate lift.
3. Roll the plane
The pilot will roll the plane in the opposite direction it rolled during the stall.
4. Adjust thrust
Stalls can occur anywhere between low to maximum thrust.
The pilot needs to adjust the thrust to an appropriate level.
5. Return to the flight path
Once the plane is stable, the pilot will readjust to its original flight path.
Aircraft Stalling is Uncommon
It’s uncommon for aircraft to stall.
General aviation planes are much, much more likely to stall than commercial ones, and most aircraft stall while taking off or landing rather than when cruising.
A report by AOPA reveals that aircraft stalls caused between 17-29% of aviation incidents between 2000 and 2014.
But stalls only accounted for 0.5% of incidents involving commercial planes.
2 Famous Stall-Related Plane Crashes
Two of the most famous stall-related plane crashes include:
1. Thai Airways International Flight 261
Thai Airways International Flight 261 flew on 11 December 1998 from Bangkok, Thailand, to Surat Thani, Thailand.
The plane stalled and crashed into a swamp, killing 101 people, while attempting to land at the airport.
2. China Airlines Flight 676
China Airlines Flight 676 crashed into a road and residential area in Taoyuan, Taiwan, in 1998.
The plane crashed because of a stall caused by the pilot attempting a manual go-around.
The crash killed all 196 people onboard, including the governor of Taiwan’s central bank, Sheu Yuan-dong.
In conclusion:
An aircraft stall is caused by a plane reaching or exceeding its critical angle of attack.
A plane’s critical angle of attack is the angle at which its airfoils generate maximum lift. Exceeding this angle prevents the plane’s wings from generating lift.
The absence of lift causes the plane to fall from the sky unless corrected.
Aircraft stalls are extremely dangerous since they can, and have, caused plane crashes.
Pilots can correct aircraft stalls by disabling the plane’s autopilot and reducing the plane’s pitch to reduce its critical angle of attack.
The pilot would also need to roll the plane if one of the wings stalled before the other, causing an unintended roll.
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.
