RECOGNITION OF STALLS


Chapter 4—Slow Flight, Stalls, and Spins
Table of Contents Introduction Slow Flight Flight at Less than Cruise Airspeeds Flight at Minimum Controllable Airspeed Stalls Recognition of Stalls Fundamentals of Stall Recovery Use of Ailerons/Rudder in Stall Recovery Stall Characteristics Approaches to Stalls (Imminent Stalls)—Power-On or Power-Off Full Stalls Power-Off Full Stalls Power-On Secondary Stall Accelerated Stalls Cross-Control Stall Elevator Trim Stall Spins Spin Procedures Entry Phase Incipient Phase Developed Phase Recovery Phase Intentional Spins Weight and Balance Requirements	RECOGNITION OF STALLS Pilots must recognize the flight conditions that are conducive to stalls and know how to apply the necessary corrective action. They should learn to recognize an approaching stall by sight, sound, and feel. The following cues may be useful in recognizing the approaching stall. Vision is useful in detecting a stall condition by noting the attitude of the airplane. This sense can only be relied on when the stall is the result of an unusual attitude of the airplane. Since the airplane can also be stalled from a normal attitude, vision in this instance would be of little help in detecting the approaching stall. Hearing is also helpful in sensing a stall condition. In the case of fixed-pitch propeller airplanes in a power-on condition, a change in sound due to loss of revolutions per minute (r.p.m.) is particularly noticeable. The lessening of the noise made by the air flowing along the airplane structure as airspeed decreases is also quite noticeable, and when the stall is almost complete, vibration and incident noises often increase greatly. Kinesthesia, or the sensing of changes in direction or speed of motion, is probably the most important and the best indicator to the trained and experienced pilot. If this sensitivity is properly developed, it will warn of a decrease in speed or the beginning of a settling or mushing of the airplane. Feel is an important sense in recognizing the onset of a stall. The feeling of control pressures is very important. As speed is reduced, the resistance to pressures on the controls becomes progressively less. Pressures exerted on the controls tend to become movements of the control surfaces. The lag between these movements and the response of the airplane becomes greater, until in a complete stall all controls can be moved with almost no resistance, and with little immediate effect on the airplane. Just before the stall occurs, buffeting, uncontrollable pitching, or vibrations may begin. Several types of stall warning indicators have been developed to warn pilots of an approaching stall. The use of such indicators is valuable and desirable, but the reason for practicing stalls is to learn to recognize stalls without the benefit of warning devices. Previous \| Next
Copyright 2012 PED Publication

Chapter 4—Slow Flight, Stalls, and Spins

Table of Contents
Introduction
Slow Flight
    Flight at Less than Cruise Airspeeds
    Flight at Minimum Controllable Airspeed
Stalls
    Recognition of Stalls
    Fundamentals of Stall Recovery
    Use of Ailerons/Rudder in Stall Recovery
    Stall Characteristics
    Approaches to Stalls (Imminent Stalls)—Power-On or Power-Off
    Full Stalls Power-Off
    Full Stalls Power-On
    Secondary Stall
    Accelerated Stalls
    Cross-Control Stall
    Elevator Trim Stall
Spins
    Spin Procedures
        Entry Phase
        Incipient Phase
        Developed Phase
        Recovery Phase
Intentional Spins
    Weight and Balance Requirements

RECOGNITION OF STALLS

Pilots must recognize the flight conditions that are conducive to stalls and know how to apply the necessary corrective action. They should learn to recognize an approaching stall by sight, sound, and feel. The following cues may be useful in recognizing the approaching stall.

Vision is useful in detecting a stall condition by noting the attitude of the airplane. This sense can only be relied on when the stall is the result of an unusual attitude of the airplane. Since the airplane can also be stalled from a normal attitude, vision
in this instance would be of little help in detecting the approaching stall.
Hearing is also helpful in sensing a stall condition. In the case of fixed-pitch propeller airplanes in a power-on condition, a change in sound due to loss of revolutions per minute (r.p.m.) is particularly noticeable. The lessening of the noise made by the air flowing along the airplane structure as airspeed decreases is also quite noticeable, and when the stall is almost complete, vibration and incident noises often increase greatly.
Kinesthesia, or the sensing of changes in direction or speed of motion, is probably the most important and the best indicator to the trained and experienced pilot. If this sensitivity is properly developed, it will warn of a decrease in speed or the beginning of a settling or mushing of the airplane.
Feel is an important sense in recognizing the onset of a stall. The feeling of control pressures is very important. As speed is reduced, the resistance to pressures on the controls becomes progressively less. Pressures exerted on the controls tend to become movements of the control surfaces. The lag between these movements and the response of the airplane becomes greater, until in a complete stall all controls can be moved with almost no resistance, and with little immediate effect on the airplane. Just before the stall occurs, buffeting, uncontrollable pitching, or vibrations may begin.

Several types of stall warning indicators have been developed to warn pilots of an approaching stall. The use of such indicators is valuable and desirable, but the reason for practicing stalls is to learn to recognize stalls without the benefit of warning devices.

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