Why Airplanes Stall: It’s Not About Airspeed

When student pilots first learn about stalls, it’s easy to associate them with one thing: flying too slowly.

After all, aircraft have published stall speeds, instructors demonstrate stalls by reducing airspeed, and the airspeed indicator even has markings associated with stall speeds.

But an airplane does not stall simply because it gets too slow.

A wing stalls when it exceeds its critical angle of attack.

That distinction is extremely important because an airplane can stall at a higher-than-published airspeed, during a steep turn, while climbing, or even with the nose below the horizon.

Understanding why requires looking beyond the airspeed indicator and understanding what is actually happening to the wing.

What Is a Stall?

A stall occurs when the smooth airflow over a wing becomes sufficiently separated because the wing has exceeded its critical angle of attack.

The wing does not suddenly stop producing all lift. Instead, once the critical angle of attack is exceeded, airflow separation increases significantly and the wing experiences a substantial loss of lift along with an increase in drag.

The key concept is this:

A stall is fundamentally an angle-of-attack problem, not an airspeed problem.

Understanding Angle of Attack

Angle of attack, or AOA, is the angle between the wing's chord line and the relative wind.

The chord line is an imaginary straight line extending from the leading edge to the trailing edge of the wing.

Relative wind is the airflow relative to the wing's flight path. It acts opposite the aircraft's direction of movement through the surrounding air mass.

As angle of attack increases, lift generally increases, up to a point. Eventually, the wing reaches its critical angle of attack. Beyond this angle, airflow can no longer remain sufficiently attached to the wing's upper surface. Separation increases rapidly, lift decreases, and drag increases.

The wing has stalled.

So Why Do We Have a "Stall Speed"?

If stalls are caused by angle of attack, why does your POH publish specific stall speeds?

Because those speeds represent stalls under specific conditions.

For example, a published stall speed may assume a particular:

• Aircraft weight

• Center of gravity

• Configuration

• Power setting

• Bank angle or load factor

Change those conditions and the speed at which the aircraft reaches its critical angle of attack can change too.

This is why thinking of stall speed as one fixed number can be misleading.

The critical angle of attack remains the underlying aerodynamic limit, while the airspeed at which you reach it can vary.

An Airplane Can Stall at a Higher Airspeed

Consider an airplane performing a steep, level turn. As bank angle increases, the lift vector tilts. Only part of the total lift now acts vertically to oppose the airplane's weight. To maintain altitude, the pilot must increase total lift.

One way the aircraft accomplishes this is by increasing angle of attack.

This also increases the aircraft's load factor.

At 60° of bank in a coordinated, level turn, the airplane experiences approximately 2 Gs.

As load factor increases, stall speed increases.

The relationship can be approximated by:

New Stall Speed = Normal Stall Speed × √Load Factor

Suppose an airplane normally stalls at 50 knots.

At a load factor of 2 G:

50 × √2 ≈ 71 knots

The same airplane that stalls around 50 knots under the original conditions could now stall at approximately 71 knots.

That is an accelerated stall.

The airplane did not suddenly develop a different critical angle of attack. Instead, the increased aerodynamic loading caused it to reach that critical angle at a higher airspeed.

What Is an Accelerated Stall?

An accelerated stall is a stall that occurs at a load factor greater than 1 G.

These stalls can occur during maneuvers such as:

• Steep turns

• Abrupt control inputs

• Pull-ups

• Certain maneuvering situations

This is one reason pilots should never assume:

"I'm well above the published stall speed, so I can't stall."

Depending on the aircraft's loading and maneuvering, that assumption can be wrong.

Can an Airplane Stall With the Nose Down?

Yes.

Another common misconception is that a stall requires a dramatically nose-high attitude.

It doesn't.

Remember that angle of attack is measured between the chord line and relative wind, not between the airplane and the horizon.

If the aircraft's flight path is descending, the relative wind changes accordingly.

It is therefore possible for an airplane to exceed its critical angle of attack even while the nose is at or below the horizon.

Pitch attitude and angle of attack are not the same thing.

This distinction becomes especially important when understanding stalls during maneuvering flight.

Why Stall Speed Increases in a Turn

Student pilots are often taught that stall speed increases with bank angle. More precisely, stall speed increases when load factor increases.

In a coordinated, level turn, increasing bank angle requires additional total lift to maintain altitude. Producing that additional lift increases load factor and ultimately requires a higher angle of attack.

As a result, the aircraft reaches its critical angle of attack at a higher airspeed.

This is particularly important when maneuvering close to the ground.

A Classic Example: The Base-to-Final Turn

Imagine a pilot overshoots the final approach course.

Instead of accepting the overshoot and correcting safely, the pilot increases bank while also applying excessive inside rudder in an attempt to point the nose toward the runway.

The airplane may become uncoordinated. If the pilot simultaneously increases back pressure, angle of attack can increase toward the critical value.

If the wing stalls in this condition, the airplane may enter an incipient spin at an altitude where recovery may be difficult or impossible. The danger isn't simply that the airplane was "too slow."

The larger problem is the combination of:

high angle of attack + uncoordinated flight + insufficient altitude.

That is why maintaining coordinated flight and making disciplined decisions in the traffic pattern are so important.

Common Stall Misconceptions

"An airplane stalls when it gets too slow."

Not exactly.

Low airspeed often requires a higher angle of attack to maintain lift, which is why stalls frequently occur at low speeds. But the actual stall occurs when the wing exceeds its critical angle of attack.

"If I'm above stall speed, I can't stall."

False.

Increased load factor can increase stall speed significantly.

"The nose has to be high for the airplane to stall."

False.

Pitch attitude and angle of attack are different. An aircraft can stall in a level, climbing, or descending attitude.

"A stall means the wing produces zero lift."

False.

A stalled wing can still produce lift. The problem is that lift decreases significantly while drag increases as airflow separation grows.

"Bank angle causes stalls."

Not directly.

Banking alone does not make the wing stall. In a level turn, however, increasing bank requires greater total lift, which increases load factor and the angle of attack required to maintain altitude.

How Do You Recover From a Stall?

The most important aerodynamic action during stall recovery is to reduce the angle of attack below the critical angle.

Depending on the aircraft and situation, recovery generally involves reducing angle of attack, applying power as appropriate, maintaining coordinated flight, leveling the wings as appropriate, and returning to the desired flight path while avoiding a secondary stall.

Pilots should always follow the recovery procedure specified for their aircraft and the procedures taught by their instructor.

Adding power alone does not fundamentally "unstall" the wing.

Reducing the angle of attack does.

The Big Picture

Instead of thinking:

"How slow can I fly before the airplane stalls?"

A better question is:

"What is happening to my angle of attack and load factor?"

Once you understand that distinction, several concepts in flight training begin to connect:

• Why stall speed increases during accelerated flight

• Why steep turns require more lift

• Why an airplane can stall above its published stall speed

• Why stalls can occur with the nose below the horizon

• Why coordinated flight matters

• Why reducing angle of attack is fundamental to stall recovery

The airspeed indicator is an important instrument, but it does not directly tell you how close the wing is to its critical angle of attack.

Understanding the aerodynamics behind the numbers is what turns memorized information into practical pilot knowledge.

At ATA Flight School, we focus on helping students understand not just what an airplane does, but why it does it. Building that foundation creates safer, more knowledgeable pilots who can apply aerodynamic principles in real-world flying.