Stalling

Forces in a Stall

A stall occurs when the wing exceeds its critical angle of attack (approximately 12 to 15 degrees for most light aircraft). At this point, the smooth airflow over the upper surface of the wing separates catastrophically, causing a marked loss of lift.

The key principle: a stall occurs at an angle, not a speed. The wing does not know how fast it is going — it only responds to the angle at which air meets its surface. However, since most light training aircraft lack angle-of-attack indicators, airspeed is your primary practical reference for stall proximity.

When the wing stalls:

• Lift decreases dramatically (by 30-50% in an instant)
• Drag increases sharply
• The nose pitches down (due to the rearward shift in center of pressure)
• The airplane may roll to one side if the stall is asymmetric

Control Effectiveness

At and near the stall, the flight controls behave very differently from normal flight:

• Ailerons: Very ineffective and potentially dangerous. Because the wing is at or beyond the critical angle of attack, deflecting an aileron DOWN (to raise a dropped wing) increases the local angle of attack on that wing further, potentially deepening the stall on that wing and making the roll worse.
• Rudder: Still effective because it operates in the propeller slipstream and in undisturbed airflow. This is why rudder is used to correct wing drop at the stall — NOT aileron.
• Elevator: Still effective enough for recovery. Pushing forward reduces the angle of attack across the entire wing, which is the fundamental recovery action.

Factors Affecting Stalling Speed

While the stall always occurs at the same critical angle of attack, the airspeed at which this angle is reached varies significantly depending on several factors:

Factors That Change Stalling Speed

Factor	Effect on Stall Speed	Explanation
Weight (heavier)	Increases	More lift required; higher AoA needed at any given speed
Bank angle (steeper)	Increases	Load factor increases; wing must produce more lift
Flap (extended)	Decreases	Higher CL max; wing produces more lift at lower speed
Power (applied)	Decreases slightly	Vertical component of thrust partially supports weight
Ice / contamination	Increases	Disrupts airflow; reduces CL max
CG position (forward)	Increases	Tail must produce more downforce; wing carries more load

Wing Drop at the Stall

A wing drop occurs when one wing stalls before the other, causing an asymmetric loss of lift and a rapid roll toward the stalled wing. This is caused by:

• Uneven airflow separation across the wing span
• Slight rigging asymmetries in the airframe
• Yaw at the point of stall (uncoordinated flight)
• Turbulence or gusts affecting one wing differently

The correct response to a wing drop at the stall:

1. Apply opposite rudder to prevent further yaw and roll
2. Simultaneously lower the nose (reduce angle of attack) to unstall both wings
3. Do NOT use aileron — it will deepen the stall on the dropping wing

Symptoms of Approaching Stall

Learning to recognize the approach of a stall is more important than learning to recover from one. If you can identify these symptoms early, you can prevent the stall entirely:

1. Decreasing airspeed: The airspeed indicator shows a declining trend toward the stall speed range
2. Less effective controls: The yoke/stick feels mushy; larger inputs are needed for less response
3. High nose attitude: The pitch attitude is noticeably higher than normal for the flight phase
4. Buffet / vibration: Turbulent airflow from the separated boundary layer strikes the tail, causing airframe vibration you can feel through the controls and seat
5. Stall warning horn: The aural warning activates 5-10 knots above the stall (activated by a vane or pressure sensor on the wing leading edge)

Standard Stall Recovery

The standard stall recovery is performed simultaneously — all actions happen together, not sequentially:

1. Lower the nose — reduce the angle of attack below the critical angle. This is the PRIMARY recovery action. The stall is caused by excessive angle of attack; reducing it is the cure.
2. Apply full power — to minimize altitude loss and accelerate the airplane back to a safe flying speed
3. Level the wings with rudder — if a wing has dropped, use rudder to bring wings level (not aileron)

Once the wings are unstalled and flying speed is regained, smoothly return to the desired flight attitude. The goal is to minimize altitude loss while recovering positively.

Secondary Stall

A secondary stall occurs when the pilot pulls back too aggressively during the recovery from a primary stall. By pulling the nose up too quickly or too far, the angle of attack exceeds the critical angle again before the airplane has regained sufficient speed.

To avoid a secondary stall:

• Recover smoothly — do not snatch the nose up after the initial pitch down
• Allow airspeed to build before raising the nose to climb
• Accept some altitude loss — it is far better to lose 100 feet recovering properly than to stall again closer to the ground

Departure Stall

A departure stall (also called a power-on stall or takeoff/climb stall) simulates a stall during the takeoff or climb phase. It occurs with power applied and in a nose-high attitude — exactly the configuration after takeoff.

Departure stalls are particularly dangerous because:

• They occur at low altitude — very little room for recovery
• The high power and nose-high attitude can mask the approaching stall
• Propeller effects (torque, P-factor) can cause a rapid wing drop or yaw at the stall
• The pilot may be distracted by after-takeoff tasks

Incipient Stall Recovery

The incipient stall is the developing stall — the phase between recognizing the first symptoms and the full stall break. Recovering at this point is the key practical skill because:

• It requires less altitude loss than recovering from a full stall
• There is no wing drop or loss of control to manage
• It represents how you will actually use stall awareness in real flying — recognizing and correcting BEFORE the stall occurs

Incipient stall recovery technique:

1. At the first recognition of stall symptoms (buffet, stall warning, sloppy controls) — immediately reduce angle of attack (lower the nose slightly)
2. Apply power as needed to arrest any altitude loss
3. The stall is prevented; the airplane continues flying