Stalls and Spin Awareness

Stalls and spin awareness is a critical skill for any pilot, whether flying a real aircraft or a simulator like FlightGear. This page explains the aerodynamics behind stalls, the factors that influence stall speed, how to recognize an impending stall, and how to safely enter and recover from stalls.

Aerodynamics of stalls

A stall occurs when the angle of attack (AoA) exceeds the critical angle at which the wing can no longer produce sufficient lift. It is not caused by low airspeed alone—although airspeed and AoA are closely related.

• The critical AoA is typically around 16–18° for most general aviation aircraft.
• As the critical AoA is approached, airflow separates from the upper surface of the wing, resulting in a sudden loss of lift, a nose‑down pitch tendency, and often a wing drop.

Factors affecting stall speed

The stall speed is not fixed; it changes with configuration, weight, and load factor. FlightGear models all these effects realistically.

Landing gear and flaps

Extending flaps lowers the stall speed because it increases the wing’s camber and lift coefficient. Likewise, lowering landing gear adds drag and changes the pitch attitude, but its main effect on stall speed comes from the change in configuration. In FlightGear you can feel this by comparing stall speeds with flaps up versus full flaps.

Weight

Stall speed increases with weight. Heavier aircraft need a higher angle of attack to produce the required lift, so the critical AoA is reached at a higher indicated airspeed. Use the aircraft weight and fuel load menus to experiment.

Center of gravity (CG)

A forward CG makes the aircraft more stable but increases the stall speed slightly because the tail must produce more downforce. An aft CG reduces stall speed and can make stall recovery more challenging—especially in spin‑prone aircraft.

Load factor and bank angle

In a turn, the load factor increases, and stall speed rises with the square root of the load factor. For example, a 60° bank (2 g) increases stall speed by about 40%. FlightGear’s turn coordinator and accelerometer (/instrumentation/g-meter) help you visualise this relationship.

Unintentional power‑off stalls – when they happen

Power‑off stalls typically occur during approach and landing phases. Common scenarios:

• Final approach with excessive nose‑up trim or too slow airspeed.
• A steep turn in the pattern, especially when base‑to‑final is overshot.
• Abrupt pitch‑up during a go‑around before the aircraft has accelerated.

In FlightGear, practice these scenarios by setting up a short approach, then pulling the throttle to idle and trying to maintain altitude with back pressure until the stall warning sounds.

Unintentional power‑on stalls – when they happen

Power‑on stalls are most common during takeoff and climb, or when practicing go‑arounds. Look out for:

• A high pitch attitude immediately after takeoff, especially with a low‑power aircraft.
• Aggressive climbing turns, such as those used to avoid obstacles.
• Attempting to climb too steeply after a go‑around while the flaps are still extended.

Many FlightGear aircraft feature a realistic stall horn that becomes audible just before the stall. Use it to build your awareness.

Recognizing stall indications

Whether power‑on or power‑off, the first signs of an approaching stall are similar:

• A decreasing audible stall warning (horn or tone) – in FlightGear, check that the aircraft you fly has a stall horn modelled; many do.
• Buffeting or shaking of the airframe – you can feel this in the simulator through force feedback (if available) or see it in the cockpit instruments.
• Reduced control effectiveness, particularly in roll (mushy ailerons).
• Pitch‑up tendency even though you are not pulling back further.

For power‑on stalls the nose will be high and the aircraft may yaw left (in a single‑engine propeller aircraft) due to torque and P‑factor. In FlightGear, you can observe this yaw by watching the turn coordinator or the slip/skid ball.

Practicing power‑off stalls

Power‑off stalls are usually demonstrated in descending flight, straight or turning.

Straight‑ahead power‑off stall

1. Clear the area (use external views or traffic display).
2. Reduce power to idle and maintain altitude by increasing pitch until the airspeed bleeds off.
3. As the stall warning sounds or buffeting begins, hold the nose up until the stall breaks.
4. Recover by lowering the nose, applying full power, and leveling the wings.

Turning power‑off stall

1. Enter a 20–30° bank turn, power idle.
2. Add back pressure to hold altitude; the inside wing may stall first, causing a roll toward the low wing.
3. Recover by rolling wings level, lowering nose, and applying power.

Practicing power‑on stalls

Power‑on stalls simulate a takeoff or go‑around scenario.

1. Establish a climb configuration (takeoff flaps, gear up if retractable).
2. Apply full power and pitch up to a nose‑high attitude (typically 20–25°).
3. Maintain that attitude until the stall occurs—the aircraft may buffet, yaw, and then drop the nose.
4. Recovery: reduce pitch, ensure wings are level, and then apply full power if not already set. In a simulator, it’s good practice to check that you haven’t inadvertently induced a spin.

Entry technique and minimum altitude

When practicing stalls in FlightGear (or in a real aircraft), always respect a safe altitude.

• Minimum entry altitude: At least 1500 ft AGL for entry, allowing recovery by 1000 ft AGL. For spins, the recommended altitude is higher (typically 3000 ft AGL or more).
• Entry technique: Smoothly increase pitch (for power‑off) or apply power while raising the nose (for power‑on). Avoid abrupt control inputs that could lead to a secondary stall or spin.

The autopilot can be used to hold altitude while you configure the aircraft, but remember to disconnect it before starting the maneuver.

Coordination of flight controls

Proper coordination is vital to prevent a stall from developing into a spin. Always use rudder to keep the slip/skid ball centered.

• In a power‑on stall, right rudder (for most single‑engine aircraft) is needed to counteract left‑turning tendencies.
• In a turning stall, step on the high wing to keep the ball centered; if a wing drops during the stall, use opposite rudder to pick it up while lowering the nose.

FlightGear provides a visual slip/skid indicator in most cockpits. You can also enable the on‑screen “ball” via the HUD options.

Recovery technique

The standard stall recovery is:

1. Reduce angle of attack – push the nose down decisively. In FlightGear, this often means a brisk forward movement of the joystick or yoke.
2. Apply full power (except for power‑off stalls where power is already idle – add it during recovery).
3. Roll wings level if a wing dropped.
4. Retract flaps (if extended) after a positive rate of climb is established.

Minimum recovery altitude is the point at which you must be fully recovered to avoid ground contact. In the simulator, treat 1000 ft AGL as the hard floor for training stalls.