Maneuvering During Slow Flight

What is Slow Flight?

Slow flight is when the airplane is flown at an angle of attack (AOA) just below the angle that causes an aerodynamic buffet or the activation of a stall warning device. A small increase in AOA may result in an impending stall, which increases the risk of an actual stall.

For pilot training and testing purposes, slow flight includes two main elements:

• Slowing to, maneuvering at, and recovering from an airspeed at which the airplane is still capable of maintaining controlled flight without activating the stall warning (5–10 knots above the 1G stall speed is a good target).
• Performing slow flight in configurations appropriate to takeoffs, climbs, descents, approaches, and go-arounds.

Special Emphasis Items

Left-Turning Tendencies: In propeller-driven airplanes, torque, slipstream effect, and P-factor produce strong left yaw, which requires right rudder input to maintain coordinated flight.

Reduced Control Effectiveness: The airplane is less responsive to flight control inputs at slower airspeeds. Pilots sometimes refer to it as "sloppy" or "mushy" controls.

Reduced Forward Visibility: The horizon may not be visible in front of the airplane in high-pitch attitudes. The "Lindbergh" visual reference can help maintain coordinated flight.

Power:

• A combination of higher power settings and reduced airflow into the cowling results in higher engine temperatures.
• In fixed-pitch propeller airplanes, a loss of RPMs may be evident when at high angles of attack.

Region of Reversed Command:

• The airplane exhibits a characteristic known as speed instability, in which lower airspeeds require higher power settings to hold altitude.
• Small pitch changes result in large airspeed changes due to variations in induced drag. As a result, pitch becomes more effective for controlling airspeed and power more effective for controlling altitude.

Bodily Sensations Experienced

Feel: Control pressures change as airspeed is reduced. Just before the stall occurs, buffeting, uncommanded rolling, or vibrations may begin to occur.

Vision: When a stall results from an unusual attitude, vision is useful for checking the pitch attitude. However, an airplane can also be stalled in a normal attitude, in which case vision cannot aid in detecting the stall.

Hearing: As airspeed decreases, a change in sound is made by the air flowing along the airplane structure. A loss of engine RPM is noticeable in an airplane with a fixed-pitch propeller.

Kinesthesia: Changes in direction or speed can be sensed by experienced pilots to warn of an impending stall.

Target Airspeed for Slow Flight

Maneuvering the airplane in slow flight is practiced at an airspeed just above the speed that would result in a stall warning (e.g., aircraft buffet or stall horn). If a stall warning occurs, the expectation is the pilot will take the appropriate action to correct it.

One procedure to establish this airspeed is to:

1. Slow the airplane to the stall warning in the desired configuration and note the airspeed.
2. Reduce the pitch or angle of attack (AOA) slightly and eliminate the stall warning indication.
3. Adjust power to maintain altitude, and note the airspeed required to perform the slow flight maneuver.

Minimum Controllable Airspeed (Historical)

Previously, pilots were trained to maneuver during slow flight at the minimum controllable airspeed, the airspeed at which any further increase in AOA, an increase in load factor, or reduction in power would result in an immediate stall. The FAA has since found that it is not appropriate for a pilot to fly with the stall warning present.

How to Perform Slow Flight

Pre-Maneuver Checks

• Clear the area
• Heading established and noted
• Altitude established:
• No lower than 1,500' AGL or higher if recommended by the manufacturer [ASEL]
• No lower than 3,000' AGL or higher if recommended by the manufacturer [AMEL]

• The instructor should specify the aircraft configuration and target airspeed for training purposes
• Landing configuration or as specified

Entry

• Turn carburetor heat ON if necessary.
• Gradually reduce thrust from cruise power and adjust the pitch to allow the airspeed to decrease while maintaining altitude.
• When the airspeed is below the maximum landing gear extension speed (V_LE), extend the landing gear, if applicable.
• Extend the flaps in increments once the airspeed is at or below the maximum flap extension speed (V_FE).

• As the airplane slows down:
• Increase the pitch attitude gradually until reaching the target airspeed.
• Add power to maintain altitude.
• Apply rudder pressure to maintain coordinated flight.
• Adjust the trim as necessary.

Execution

• Accomplish straight-and-level flight, turns, climbs, and descents as specified by the instructor or evaluator.

At All Times:

• Ensure the airplane remains trimmed for "hands-off" flight.
• Adjust pitch to maintain the airspeed and power to maintain altitude.
• Apply right rudder to correct for left-turning tendencies, which are more prominent at low airspeeds.
• Make smooth and coordinated flight control applications. Abrupt control movements may result in a stall.

Turns:

• Turns should be practiced at various bank angles up to approximately 20°.
• Apply adequate rudder pressure to maintain coordinated flight when starting and rolling out of a turn.
• Add power to maintain altitude.

Climbs and Descents:

• Before making any changes, note the power setting for later use.
• To initiate a climb or descent, make a power adjustment. Adjust the pitch attitude to control airspeed.
• Due to the additional drag created from the landing gear and flaps being extended, large power settings are required when executing climbs.

Exit

• Smoothly apply forward pressure to reduce the angle of attack (AOA).
• Maintain coordinated flight and level the wings if necessary.
• Apply power to return to the desired flightpath.
• As airspeed increases, retract the flaps in increments.
• Retract the landing gear, if applicable.
• Verify that carburetor heat is OFF, if equipped.

• Return to the normal cruise speed, trimming as necessary.
• Complete the cruise checklist.

Common Errors for Slow Flight

• Failure to scan for traffic before and during the maneuver
• Inadequate back-elevator pressure as power is reduced, resulting in altitude loss
• Excessive back-elevator pressure as power is reduced, resulting in a climb followed by a rapid reduction in airspeed
• Insufficient rudder pressure to correct for torque or adverse yaw
• Fixation on the flight instruments

• Failure to anticipate pitch changes as flaps are extended or retracted
• Inadequate power management
• Inability to adequately divide attention between airplane control and orientation
• Failure to properly trim the airplane
• Failure to respond to a stall warning

Airman Certification Standards for Slow Flight

Target Speed:

• SPT: An airspeed at which any further increase in angle of attack, increases in load factor, or reduction in power, would result in an immediate stall (minimum controllable airspeed).
• PVT and COM: An airspeed at which any further increase in angle of attack, increase in load factor, or reduction in power, would result in a stall warning (e.g., aircraft buffet or stall horn).

Configuration: As specified by the evaluator.