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Airplane Stall &Recovery Procedures

Introduction:

Stall Avoidance:

  • Avoid flying at minimum airspeeds
  • Remain in the normal flight envelope
  • Avoid abrupt maneuvers

Stall Characteristics:

  • During a rapid departure from controlled flight, the normal CLmax may be momentarily exceeded and as a result, the aircraft could be overstressed or damaged below the corner speed (maneuvering airspeed)
  • If the airplane is slipping toward the inside of the turn at the time of the stall, it tends to roll rapidly toward the outside of the turn as the nose pitches down, because the outside wing stalls before the inside wing
  • If the airplane is skidding toward the outside of the turn, it will have a tendency to roll to the inside of the turn, because the inside wing stalls first
  • If the coordination of the turn at the time of the stall is accurate, the airplane's nose will pitch away from the pilot just as it does in a straight flight stall
  • Stalling will occur at a higher airspeed and thus, a lower than expected pitch resulting in a quick, unexpected stall
  • If an uncoordinated turn is made, one wing may tend to drop suddenly, causing the airplane to roll in that direction; if that occurs, the excess back-elevator pressure must be released, power added, and the airplane returned to straight-and-level flight with coordinated control pressure

Load Factor:

  • Load factor is the weight the wings are supporting
  • Load factor is generally not calculated as part of preflight however, it has a close relation to stall speed, which is very important
    • As load factor increase, stall speed increases
  • In level flight, the load factor is the weight of the aircraft
    • This is due to the aircraft feeling "1-g" or 1 times the force of gravity
  • As you increase the angle of bank however, a pilot must pull back on the controls in order to avoid descending due to the loss of vertical lift, which then raises the load factor
  • Calculating Load Factor:

    • Crosswind Component Chart
      Load Factor vs. Stall Speed
    • Load Factor Formula:

      Load Factor = 1 / cos(angle of bank)
    • Conditions:

      • Given an angle of Bank of 60°
    • Calculation:

      • Load Factor = 1 / cos(60)
      • Load Factor = 1 / 0.5
      • Load Factor = 2
    • Chart:

      [Figure 1]
      • Look at the 60° mark at the bottom of the chart and move up until you intercept the load factor reference line
      • Move over to the left and see the load factor imposed on the aircraft
        • You should come up to approximately 2
    • Crosswind Component Chart
      Load Factor vs. Stall Speed

Stall Speed & Angle of Bank:

  • As mentioned above, stall speed increases with load factor due to a loss in the vertical component of lift
  • Calculating Stall Speed:

    • Load Factor Formula:

      Stall Speed Banked = [Stall Speed Level x Square Root of Load Factor]
    • Conditions:

      • Given an aircraft with a stall speed of 48 knots with a load factor of 2 (60° angle of bank):
    • Calculation:

      • Stall Speed Banked = [Stall Speed Level / Square Root of Load Factor]
      • Square Root of 2 = 1.41
      • Stall Speed Banked = 48 x 1.41
      • Stall Speed Banked = 68 KIAS
    • Chart:

      [Figure 1]
      • Look at the 60° mark at the bottom of the chart and move up until you intercept the stall speed increase reference line
      • Move over to the left and see the percent increase in stall speed
        • You should come up with an increase in stall speed of approximately 41%
          • Stall Speed Banked = [Stall Speed Level x percent increase in stall speed]
          • Stall Speed Banked = 48 x 1.41
          • Stall Speed Banked = 68 KIAS

Approaches to Stalls:

  1. Select an altitude where recovery will occur no lower than 1500' AGL
  2. Commence a clearing turn
  3. While maintaining heading, reduce power, adjusting pitch (trim) to maintain altitude
  4. For Dirty Configuration:
    • Below VLO, extend the landing gear and verify 3 down and locked
    • Below VFE, extend the flaps for takeoff or landing configurations
    • Adjust pitch (trim) to maintain altitude
  5. Advance the propeller control to full forward (high rpm) as required
  6. While maintaining altitude, slowly establish the pitch attitude, power setting, and if applicable, bank (15-30°) that would induce a stall
  7. At the first indication of an impending stall, calling, "stalling," and initiate recovery, maintaining heading while/ smoothly and continuously increasing power to full and adjusting pitch to maintain altitude (trim)
  8. For Dirty Configuration:
    • As airspeed increases, raise the flaps in increments, to 10°:
      • Too abrupt of flap retraction will result in a dramatic loss of lift and possibly stall
    • As airspeed increases, but below VLO raise the landing gear
    • At or above Vx retract flaps to 0°
  9. As cruise airspeed is attained, set cruise power
    • Re-trim as necessary
  10. Complete the Cruise Flow/Checklist

Power-Off Stalls:

  • Airplane Flying Handbook, Figure 4-5. Power-Off Stall
    Airplane Flying Handbook, Power-Off Stall
  • Airplane Flying Handbook, Figure 4-5. Power-Off Stall
    Airplane Flying Handbook, Power-Off Stall
  • Power-off stalls simulate a stall during the normal approach to landing
    • Should be set up in the landing configuration
  • Recoveries therefore train a pilot to make prompt, positive, and effective recoveries with a minimum loss of altitude
  • This stall may occur while descending in an actual or simulated emergency or in any power-off situation when airspeed is not controlled
  • Power-Off Stall & Recovery Procedure:

    1. Select an altitude where recovery will occur no lower than 1500' AGL
    2. Perform clearing turns
    3. Reduce power adjusting pitch to maintain altitude
      • Trim as necessary
    4. Below VLO, extend the landing gear, as required
      • Callout: "Gear Down"
      • Verify gear DOWN and callout "3 Green, No Red
    5. Below VFE, extend the flaps
    6. Advance the propeller control to full forward (high rpm) as required
    7. Maintain altitude until reaching a normal approach speed and then maintain that speed in a stabilized descent
    8. Descending no lower than 200', simultaneously reduce power to idle and pitch up to Vy attitude (4-5 degrees, cowling on the horizon)
      • This pitch attitude will be a normal landing attitude
      • Above 5 knots, above stall speed the horn will sound
      • Stall may be performed level or with up to 20° bank angles
    9. At the stall, call out "stalling"
    10. Reduce the AoA to regain control
    11. Add full power
    12. Pitch for Vy
      • Glare shield level with the horizon
    13. Maintain coordination using rudder to prevent spins
    14. With a positive rate of climb established:
      • Begin to raise the flaps in 10° increments
      • Below VLO, and with a positive rate of climb established, call out "positive climb, gear up," and retract the landing gear
      • Note, some aircraft Pilot Operating Handbooks may require flaps be partially retracted before a positive rate of climb is possible
    15. Complete cruise checklist, returning to the altitude, heading, and airspeed required
  • Power-Off Stall & Recovery Common Errors:

    • Failure to adequately clear the area
    • Failure to establish the specified landing gear and flap configuration prior to entry
    • Improper pitch, heading, and bank control during straight ahead stalls
    • Use outside and instrument references
    • Right rudder in nose-high power-on condition; release at break
    • Improper pitch and bank control during turning stalls
    • Rough or uncoordinated control technique
    • Failure to recognize the first indications of a stall
    • Failure to achieve a stall
    • Improper torque correction
    • Poor stall recognition and delayed recovery
    • Excessive altitude loss or excessive airspeed during recovery
    • Secondary stall during recovery
  • Power-Off Stall Airman Certification Standards:

Power-On Stalls:

  • Helps recognize the indications of an imminent or full stall during power-on situations with the landing gear down and to make prompt, positive, and effective recoveries with a minimum loss of altitude
  • Power-on stalls simulate a stall from normal takeoff and departure
  • Power-On Stall & Recovery Procedure:

    1. Select an altitude where recovery will occur no lower than 1500' AGL
    2. Perform clearing turns
    3. Reduce power adjusting pitch to maintain altitude
      • Trim as necessary
    4. Below VLO, extend the landing gear, as required
      • Callout: "Gear Down"
      • Verify gear DOWN and callout "3 Green, No Red
    5. At Vr set full power and slowly increase pitch up to approx. 18° in straight flight or in turns with up to 20° bank
      • Bring the rudder pedals to the horizon
    6. At the stall, call out, "stalling," and reduce the angle of attack to regain control effectiveness
    7. Add full power to regain airspeed
    8. Pitch up to a Vx attitude
      • Bring the horizon through the top 4th of the panel
    9. Maintain coordinated use of the ailerons and rudder to level the wings and prevent entering into a spin
    10. Adjust pitch to Vy attitude and minimize altitude loss
      • Trim as necessary
    11. With a positive rate of climb established:
      • Below VLO, and with a positive rate of climb established, call out "positive climb, gear up," and retract the landing gear
    12. Complete cruise checklist
  • Power-On Stall & Recovery Common Errors:

    • Failure to adequately clear the area
    • Failure to establish the specified landing gear and flap configuration prior to entry
    • Improper pitch, heading, and bank control during straight ahead stalls
    • Use outside and instrument references
    • Right rudder in nose-high power-on condition; release at break
    • Improper pitch and bank control during turning stalls
    • Rough or uncoordinated control technique
    • Failure to recognize the first indications of a stall
    • Failure to achieve a stall
    • Improper torque correction
    • Poor stall recognition and delayed recovery
    • Excessive altitude loss or excessive airspeed during recovery
    • Secondary stall during recovery
  • Power-On Stall Airman Certification Standards:

Cross-Controlled Stalls:

  • Cross-control stalls emphasize the importance of using coordinated control pressures whenever making turns
  • Most apt to occur during a poorly planned and executed base-to-final approach turn
  • Practicing approaches to stalls demonstrates the transition from cruise flight to critically slow airspeeds in various conditions
  • Cross-Controlled Stall & Recovery Procedure:

    WARNING:
    All procedures are GENERALIZED.
    Always fly per Pilot Operating Handbook procedures,
    observing any relevant Standard Operating Procedures (SOPs)


    1. Airplane Flying Handbook, Figure 4-6. Power On Stall
      Airplane Flying Handbook, Power On Stall
    2. Airplane Flying Handbook, Figure 4-6. Power On Stall
      Airplane Flying Handbook, Power On Stall
    3. Select an altitude where recovery will occur no lower than 1500' AGL
    4. Commence a clearing turn
    5. Reduce power adjusting pitch to maintain altitude
      • Trim as necessary
    6. Below VLO, extend the landing gear, as required
      • Callout: "Gear Down"
      • Verify gear DOWN and callout "3 Green, No Red
    7. Advance the propeller control to full forward (high rpm) as required
    8. Maintain altitude until reaching a typical approach speed, and then establish a stabilize descent (trimmed) to simulate a normal approach to landing
    9. Descending no lower than 200' from the entry altitude, simultaneously reduce power to idle and pick a reference point off the left or right wing tip
    10. Turn towards the reference point using a 25-30° bank while:
      • Simultaneously applying excessive rudder pressure in the direction of turn (thereby accelerating the speed of outer wing)
      • Using opposite aileron to prevent over-banking (maintain a constant 25-30° bank) during the turn, and
      • Increasing elevator back-pressure to keep the nose from lowering
    11. At the imminent stall, callout, "stalling," reduce the angle of attack to regain control effectiveness, and apply full power
    12. Maintain coordinated use of the ailerons and rudder to level the wings and prevent entering into a spin
    13. Adjust pitch to the Vy attitude and minimize altitude loss
      • Re-trim as necessary
    14. Below VLO, and with a positive rate of climb established, call out "positive climb, gear up," and retract the landing gear
    15. Complete cruise checklist, returning to the altitude, heading, and airspeed required
      • Note that completion of the maneuver should occur by the 90° reference point and before full deflection of the rudder and aileron
  • Cross-Controlled Stall Common Errors:

    • Failure to adequately clear the area
    • Failure to establish the specified landing gear and flap configuration prior to entry (usually flaps up to avoid exceeding VFE
    • Improper pitch, heading, and bank control during straight ahead stalls
    • Use outside and instrument references
    • Right rudder in nose-high power-on condition; release at break
    • Improper pitch and bank control during turning stalls
    • Rough or uncoordinated control technique
    • Failure to recognize the first indications of a stall
    • Failure to achieve a stall
    • Improper torque correction
    • Poor stall recognition and delayed recovery
    • Excessive altitude loss or excessive airspeed during recovery
    • Secondary stall during recovery
  • Cross Controlled Stall Airman Certification Standards:

Accelerated Stalls:

  • A stall above 1-g flight is termed an accelerated stall
    • For this reason, you may hear of an accelerated stall referred to as a "G-Stall"
  • Accelerated stalls demonstrate stalls are a function of angle of attack and not airspeed
  • Accelerated Stall Graphic
    Accelerated Stall Graphic
  • Accelerated Stall Graphic
    Accelerated Stall Graphic
  • Accelerated Stall & Recovery Procedure:

    1. Select an altitude where recovery will occur no lower than 1500' AGL
    2. Commence a clearing turn
    3. Reduce power to allow the airplane to decelerate to cruise airspeed
    4. Ensure the flaps are up
    5. Once established at a cruise airspeed, establish a 45-50° bank to the left or right
    6. Reduce power to idle, adjusting the pitch to maintain altitude
    7. Allow the airspeed to decrease approximately 20 KIAS and then firmly increase elevator back-pressure
    8. At the imminent stall (buffet):
      • Note the indicated airspeed,
      • Callout, "stalling,"
      • Reduce the angle of attack to regain control effectiveness, and
      • Add power as necessary
    9. Maintain coordinated use of the ailerons and rudder to:
      • Level the wings,
      • Prevent entering into a spin, and
      • Minimize altitude loss by establishing Vy
      • Re-trim as necessary
    10. Return to the altitude, heading, and airspeed specified
  • Accelerated Stall and Recovery Common Errors:

    • Failure to adequately clear the area
    • Failure to establish the specified landing gear and flap configuration prior to entry
    • Improper pitch, heading, and bank control during straight ahead stalls
    • Use outside and instrument references
    • Right rudder in nose-high power-on condition; release at break
    • Improper pitch and bank control during turning stalls
    • Rough or uncoordinated control technique
    • Failure to recognize the first indications of a stall
    • Failure to achieve a stall
    • Improper torque correction
    • Poor stall recognition and delayed recovery
    • Excessive altitude loss or excessive airspeed during recovery
    • Secondary stall during recovery
  • Accelerated Stall Airman Certification Standards:

Elevator Trim Stalls:

  • Elevator trim stalls show what can happen when full power is applied for a go-around and positive control of the airplane is not maintained
  • Shows the importance of smooth power applications, overcoming strong trim forces, and maintaining positive control
  • Elevator Trim Stall & Recovery Procedure:

    1. Airplane Flying Handbook, Figure 4-8. Elevator Trim Stall
      Airplane Flying Handbook, Elevator Trim Stall
    2. Airplane Flying Handbook, Figure 4-8. Elevator Trim Stall
      Airplane Flying Handbook, Elevator Trim Stall
    3. Select an altitude where recovery will occur no lower than 1500' AGL
    4. Commence a clearing turn
    5. Reduce power, adjusting pitch (trimming) to maintain altitude
    6. Below VLO, extend the landing gear and verify 3 down and locked
    7. Below VFE, extend the flaps for takeoff or landing configurations
    8. Adjust pitch (trim) to maintain altitude
    9. Advance the propeller control to full forward (high rpm) as required
    10. Maintain altitude until reaching approach speed, and then establish a stabilized descent (trimmed) to simulate a normal approach to landing (3° down)
    11. Descending no lower than 200' from the entry altitude, apply full throttle, allowing the airplane to roll left and the pitch to increase to the Vx pitch attitude
    12. Reduce the angle of attack to regain control effectiveness
    13. Maintain coordinated use of the ailerons and rudder to level the wings
    14. Adjust pitch to the Vy attitude, raise the flaps in increments, to 10 °:
      • Too abrupt of flap retraction will result in a dramatic loss of lift and possibly stall
    15. As airspeed increases, but below VLO raise the landing gear
    16. At or above Vy retract flaps to 0°
    17. As cruise airspeed is attained, set cruise power
      • Re-trim as necessary
    18. Complete the Cruise Flow/Checklist
  • Elevator Trim Stall Common Errors:

    • Failure to adequately clear the area
    • Failure to establish the specified landing gear and flap configuration prior to entry
    • Improper pitch, heading, and bank control during straight ahead stalls
    • Use outside and instrument references
    • Right rudder in nose-high power-on condition; release at break
    • Improper pitch and bank control during turning stalls
    • Rough or uncoordinated control technique
    • Failure to recognize the first indications of a stall
    • Failure to achieve a stall
    • Improper torque correction
    • Poor stall recognition and delayed recovery
    • Excessive altitude loss or excessive airspeed during recovery
    • Secondary stall during recovery
  • Elevator Trim Stall Airman Certification Standards:

Secondary Stalls:

  • Airplane Flying Handbook, Figure 4-7. Secondary Stall
    Airplane Flying Handbook, Secondary Stall
  • Airplane Flying Handbook, Figure 4-7. Secondary Stall
    Airplane Flying Handbook, Secondary Stall
  • Secondary stall are stalls that may occur after a recovery from a preceding stall
  • Secondary stalls are caused by attempting to hasten the completion of a stall recovery before the airplane has regained sufficient flying speed
    • It also occurs when the pilot fails to reduce the angle of attack sufficiently during stall recovery by not lowering pitch attitude sufficiently, or by attempting to break the stall by using power only
  • When this stall occurs, the back-elevator pressure should again be released just as in a normal stall recovery
  • When sufficient airspeed has been regained, the airplane can then be returned to straight-and-level flight
  • Performing the secondary stall procedure demonstrate the effects of improper control usage inducing another stall after initiating a recovery from the initial stall
  • Secondary Stalls & Recovery Procedure:

    1. Select an altitude where recovery will occur no lower than 1500' AGL
    2. Perform clearing turns
    3. Perform a power-off stall or power-on stall as directed
    4. At the stall, call out, "stalling," and reduce the angle of attack to regain control effectiveness
    5. Add full power to regain airspeed
    6. Maintain coordinated use of the ailerons and rudder to level the wings and prevent entering into a spin
    7. Immediately increase the pitch attitude to induce another (secondary) stall
    8. At the stall, callout, "stalling," reduce the angle of attack to regain control effectiveness
    9. Add full power to regain airspeed
    10. Maintain coordinated use of the ailerons and rudder to level the wings and prevent entering into a spin
    11. Adjust pitch to the Vx attitude, re-trimming as necessary and minimizing altitude loss
    12. With a positive rate of climb established:
      • As airspeed increases, raise the flaps in increments, to 10 °:
        • Too abrupt of flap retraction will result in a dramatic loss of lift and possibly stall
      • As airspeed increases, but below VLO raise the landing gear
      • At or above Vx retract flaps to 0°
    13. Complete cruise checklist, returning to the altitude, heading, and airspeed required
  • Secondary Stalls Airman Certification Standards:

Conclusion:

  • Stalls do NOT occur without warning
    • While flying along in cruise flight, a stall will not rip the airplane out of the sky and throw it uncontrollably to the ground to a big smoking crater
  • At high load factors, the sudden loss of lift from one wing (whichever stalls first) creates a much large rolling moment than with a 1-g stall
    • The result is a violent departure that resembles a snap roll
  • It is important to note that individual aircraft may have stall characteristics unique to them due to bends/twists which develop in the airframe over time depending on their use
  • To get more in depth about what is occurring during a stall, be sure to read the stall performance page
  • Stalls are most likely to occur unexpectedly
  • Although power-off stalls can happen in various regimes of flight, recovery procedures are particularly important while on an approach to landing
  • Although power-on stalls can happen in various regimes of flight, recovery procedures are particularly important while on an takeoff and climb
  • When teaching stalls, avoid mechanical steps, but instead introduce a stall when unexpected, as that is the most likely scenario to encounter
  • Note that flaps are not extended due to the possibility of exceeding VFE
  • Consider practicing maneuvers on a flight simulator to introduce yourself to maneuvers or knock off rust
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References: