When considering upset training conducted in an aerobatic-capable airplane in particular, the importance of employing instructors
with specialized UPRT experience in those airplanes cannot be overemphasized. Just as instrument or tailwheel instruction requires
specific skill sets for those operations, UPRT demands that instructors possess the competence to oversee trainee progress, and the
ability to intervene as necessary with consistency and professionalism. As in any area of training, the improper delivery of stall, spin,
and upset recovery training often results in negative learning, which could have severe consequences not only during the
training itself, but in the skills and mindset pilots take with them when they have passengers and place the lives of others at stake.
All-Attitude/All-Envelope Flight Training Methods
Sound UPRT encompasses operation in a wide range of possible flight attitudes and covers the airplane’s limit flight envelope . This
training is essential to prepare pilots for unexpected upsets. As stated at the outset, the primary focus of a comprehensive
UPRT program is the avoidance of, and safe recovery from, upsets. Much like basic instrument skills, which can be applied to flying
a vast array of airplanes, the majority of skills and techniques required for upset recovery are not airplane-specific. Just as basic
instrument skills learned in lighter and lower performing airplanes are applied to more advanced airplanes, basic upset recovery
techniques provide lessons that remain with pilots throughout their flying careers.
FSTD–based UPRT
UPRT can be effective in high fidelity devices (i.e., Level C and D FFS); however, instructors and pilots should be mindful of the
technical and physiological boundaries when using a particular FSTD for upset training. This training is a current requirement for
pilots seeking a multiengine airplane ATP certificate in accordance with 14 CFR part 61, section 61.156, and the training course must
be FAA approved.
Coordinated Flight
Coordinated flight occurs whenever the pilot is proactively correcting for yaw effects associated with power (engine/
propeller effects), aileron inputs, how an airplane reacts when turning, and airplane rigging. The airplane is in coordinated flight
when the airplane’s nose is yawed directly into the relative wind and the ball is centered in the slip/skid indicator (except
for cert ain multiengine airplane operation with an engine failure). [Figure 5-5]
Figure 5-5. Coordinated flight in a turn.
Angle of Attack
The angle of attack (AOA) is the angle at which the chord of the wing meets the relative wind. The chord is a straight line from the
leading edge to the trailing edge. At low angles of attack, the airflow over the top of the wing flows smoothly and produces lift with a
relatively small amount of drag. As the AOA increases, lift as well as drag increases; however, above a wing’s critical AOA, the flow
of air separates from the upper surface and backfills, burbles, and eddies, which reduces lift and increases drag. This condition is a
stall, which can lead to loss of control if the AOA is not reduced.
It is important for the pilot to understand that a stall is the result of exceeding the critical AOA, not of insufficient airspeed. The term
“stalling speed” can be misleading, as this speed is often discussed when assuming 1G flight at a particular weight and configuration.
Increased load factor directly affects stall speed (as well as do other factors such as gross weight, center of gravity, and flap setting).
Therefore, it is possible to stall the wing at any airspeed, at any flight attitude, and at any power setting. For example, if a
pilot maintains airspeed and rolls into a coordinated, level 60° banked turn, the load factor is 2G, and the airplane will stall at a speed
that is 41 percent higher than the 1G stall speed. In that 2G level turn, the pilot has to increase AOA to increase the lift
required to maintain altitude. At this condition, the pilot is closer to the critical AOA than during level flight and therefore closer
to the higher stalling speed. Because “stalling speed” is not a constant number, pilots need to understand the underlying factors
that affect it in order to maintain aircraft control in all circumstances.
Slow Flight
Flying at reduced airspeeds is normal in the takeoff/departure and approach/landing phases of flight. While pilots typically perform
these operations at low airspeeds and close to the ground, pilots learn to maneuver an airplane in slow flight at a safe altitude. During
slow flight, any further increase in angle of attack, increase in load factor, or reduction in power, will result in a stall warning (e.g.,
aircraft buffet, stall horn, etc.), and pilots should react to and correct for any stall indication. Note that stall training builds upon the
knowledge and skill acquired from the slow flight maneuver and encompasses the period of time from the stall warning (e.g., aircraft
buffet, stall horn, etc.) to the stall.
The objective of maneuvering in slow flight is to develop the pilot’s ability to fly at low speeds and high AOAs. Through practice, the
pilot becomes familiar with the feel, sound, and visual cues of flight in this regime, where there is a degraded response to
control inputs and where it is more difficult to maintain a selected altitude. It is essential that pilots:
1. understand the aerodynamics associated with slow flight in various aircraft configurations and attitudes,
2. recognize airplane cues in these flight conditions,
3. smoothly manage coordinated flight control inputs while maneuvering without a stall warning, and
4. make prompt appropriate correction should a stall warning occur.
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 to 10 knots above the 1G stall
speed is a good target.
⦁ Performing slow flight in configurations appropriate to takeoffs, climbs, descents, approaches to
landing, and go-arounds.
Slow flight should be introduced with the target airspeed sufficiently above the stall to permit safe maneuvering, but close enough to
the stall warning for the pilot to experience the characteristics of flight at a low airspeed. One way to determine the target airspeed is
to slow the aircraft to the stall warning when in the desired slow flight configuration, pitch the nose down slightly to eliminate the
stall warning, and add power to maintain altitude and note the airspeed.
When practicing slow flight, a pilot learns to divide attention between aircraft control and other demands. How the airplane feels at
the slower airspeeds demonstrates that as airspeed decreases, control effectiveness decreases. For instance, reducing airspeed from
30 knots to 20 knots above the stalling speed will result in a certain loss of effectiveness of flight control inputs because of less
airflow over the control surfaces. As airspeed is further reduced, the control effectiveness is further reduced and the reduced airflow
over the control surfaces results in larger control movements being required to create the same response. Pilots sometimes refer to the
feel of this reduced effectiveness as “sloppy” or “mushy” controls.
When flying above the minimum drag speed (L/D MAX), more power is required to fly even faster. When flying at speeds below
L/DMAX, more power is required to fly even slower. Since slow flight will be performed well below L/D MAX, the pilot should be aware
that large power inputs or a reduction in AOA will be required to prevent the aircraft from decelerating. It is important to note that
when flying below L/D MAX or on the backside of the power curve, as the AOA increases toward the critical AOA and the
airplane’s speed continues to decrease, small changes in the pitch control result in disproportionally large changes in induced drag
and therefore changes in airspeed. As a result, pitch becomes a more effective control of airspeed when flying below L/D MAX and
power is an effective control of the path.
It is also important to note that an airplane flying below L/D MAX, exhibits a characteristic known as “speed instability” and the
airspeed will continue to decay without appropriate pilot action. For example, if the airplane is disturbed by turbulence and the
airspeed decreases, the airspeed may continue to decrease without the appropriate pilot action of reducing the AOA or adding power.
[Figure 5-6]
Figure 5-6. Angle-of-attack in degrees.
Performing the Slow Flight Maneuver
Slow flight training includes:
⦁ Slowing the airplane smoothly and promptly from cruising to approach speeds without changes in altitude
or heading, while increasing the angle of attack and setting the required power and trim.
⦁ Configuration changes, such as extending the landing gear and adding flaps, while maintaining heading and
altitude.
⦁ Turning while maintaining altitude.
⦁ Straight-ahead climbs and climbing medium-banked (approximately 20 degrees) turns, and straight-ahead
ower-off gliding descents and descending turns, which represent the takeoff and landing phases of flight.
Slow flight in a single-engine airplane should be conducted so the maneuver can be completed no lower than 1,500 feet AGL (3,000
for multiengine airplanes), or higher, if recommended by the manufacturer. In all cases, practicing slow flight should be conducted at
an adequate height above the ground for recovery should the airplane inadvertently stall.
To begin the slow flight maneuver, the pilot should clear the area and gradually reduce thrust from cruise power and adjust the pitch
to allow the airspeed to decrease while maintaining altitude. As the speed of the airplane decreases, there is a change in the sound of
the airflow. As the speed approaches the target slow flight speed, which is an airspeed just above the stall warning in the desired
configuration (i.e., approximately 5 –10 knots above the stall speed for that flight condition), additional power will be needed to
maintain altitude. During these changing flight conditions, the pilot should trim the airplane to compensate for changes in control
pressures. If the airplane remains trimmed at the pre-maneuver cruising speed, strong aft (back) control pressure is needed on the
elevator, which will make precise control difficult.
Slow flight is typically performed and evaluated in the landing configuration. Therefore, both the landing gear and the flaps should be
extended to the landing position, as applicable. It is recommended the prescribed before-landing checks be completed to configure
the airplane. The extension of gear and flaps typically occurs once cruise power has been reduced and at appropriate airspeeds to
ensure limitations for extending those devices are not exceeded. Practicing this maneuver in other configurations, such as a clean or
takeoff configuration, is also good training and may be evaluated on the practical test.
With an AOA just under the AOA which may cause an aerodynamic buffet or stall warning, the flight controls are less effective .
[Figure 5-7] The elevator control is less responsive and larger control movements are necessary to retain control of the airplane. In
propeller-driven airplanes, torque, slipstream effect, and P-factor may produce a strong left yaw, which requires right rudder input to
maintain coordinated flight. The closer the airplane is to the 1G stall, the greater the amount of right rudder pressure required.
Figure 5-7. Slow flight—low airspeed, high angle of attack, high power, and constant altitude.
Maneuvering in Slow Flight
When the desired pitch attitude and airspeed have been established in straight-and-level slow flight, the pilot needs to maintain
awareness of outside references and continually cross- check the airplane’s instruments to maintain control. The pilot should note the
feel of the flight controls, especially the airspeed changes caused by small pitch adjustments, and the altitude changes caused by
power changes. The pilot should practice turns to determine the airplane’s controllability characteristics at this low speed. During the
turns, it will be necessary to increase power to maintain altitude. Abrupt or rough control movements during slow flight may result in
a stall. For instance, abruptly raising the flaps while in slow flight can cause the plane to stall.
The pilot should also practice climbs and descents by adjusting the power when stabilized in straight-and-level slow flight. The pilot
should note the increased yawing tendency at high power settings and counter it with rudder input as needed.
To exit the slow flight maneuver, add power. As airspeed and lift increase, apply forward control pressure to reduce the AOA and
maintain altitude. Maintain coordinated flight, level the wings as necessary, and return to the desired flightpath. As airspeed increases,
clean up the airplane by retracting flaps and landing gear, if they were extended, and adjust trim as needed. A pilot should anticipate
the changes to the AOA as the landing gear and flaps are retracted to avoid a stall.
Common Errors
Common errors in the performance of slow flight are:
1. Failure to adequately clear the area
2. Inadequate back-elevator pressure as power is reduced, resulting in altitude loss
3. Excessive back-elevator pressure as power is reduced, resulting in a climb followed by rapid reduction in airspeed
4. Insufficient right rudder to compensate for left yaw
5. Fixation on the flight instruments
6. Failure to anticipate changes in AOA as flaps are extended or retracted
7. Inadequate power management
8. Inability to adequately divide attention between airplane control and orientation
9. Failure to properly trim the airplane
10. Failure to respond to a stall warning
Stalls
A stall is an aerodynamic condition which occurs when smooth airflow over the airplane’s wings is disrupted, resulting in loss of lift.
Specifically, a stall occurs when the AOA —the angle between the chord line of the wing and the relative wind —exceeds the wing’s
critical AOA. It is possible to exceed the critical AOA at any airspeed, at any attitude, and at any power setting. [Figure 5-8]
Figure 5-8. Critical angle of attack and stall.
For these reasons, it is important to understand factors and situations that can lead to a stall, and develop proficiency in stall
recognition and recovery. Performing intentional stalls will familiarize the pilot with the conditions that result in a stall, assist in
recognition of an impending stall, and develop the proper corrective response if a stall occurs. Stalls are practiced to two different
levels:
⦁ Impending Stall—an impending stall occurs when the AOA causes a stall warning, but has not yet reached
the critical AOA. Indications of an impending stall can include buffeting, stick shaker, or aural warning.
⦁ Full Stall—a full stall occurs when the critical AOA is exceeded. Indications of a full stall are typically that
an uncommanded nose down pitch cannot be readily arrested, and may be accompanied by an uncommanded
rolling motion. For airplanes equipped with stick pushers, their activation is also an indicator of a full stall.
Although it depends on the degree to which a stall has progressed, some loss of altitude is expected during recovery. The longer it
takes for the pilot to recognize an impending stall, the more likely it is that a full stall will result. Intentional stalls should therefore be
performed at an altitude that provides adequate height above the ground for recovery and return to normal level flight.
Stall Recognition
A pilot should recognize the flight conditions that are conducive to stalls and know how to apply the necessary corrective action. This
level of proficiency involves learning to recognize an impending stall by sight, sound, and feel.
Stalls are usually accompanied by a continuous stall warning for airplanes equipped with stall warning devices. These devices
may include an aural alert, lights, or a stick shaker all which alert the pilot when approaching the critical AOA. Most vintage
airplanes, and many types of light-sport and experimental airplanes, do not have stall warning devices installed. However,
certification standards permit manufacturers to provide the required stall warning either through the inherent aerodynamic qualities of
the airplane (pre-stall buffeting) or through a stall warning device that gives a clear indication of the impending stall.
Other sensory cues for the pilot include:
⦁ Feel—the pilot will feel control pressures change as speed is reduced. With progressively less resistance
on the control surfaces, the pilot needs to use larger control movements to get the desired airplane
response. The pilot will notice the airplane’s reaction time to control movement increases.
⦁ Vision—since the airplane can be stalled in any attitude, vision is not a foolproof indicator of an impending
stall. However, maintaining pitch awareness is important.
⦁ Hearing—as speed decreases, the pilot should notice a change in sound made by the air flowing along the
airplane structure.
⦁ Kinesthesia—the physical sensation (sometimes referred to as “seat of the pants” sensations) of changes in
direction or speed is an important indicator to the trained and experienced pilot in visual flight. If this
sensitivity is properly developed, it can warn the pilot of an impending stall.
Pilots should remember that a level-flight 1G published stalling speed is valid only:
1. In unaccelerated 1G flight
2. In coordinated flight (slip-skid indicator centered)
3. At one weight (typically maximum gross weight)
4. At a particular center of gravity (CG) (typically maximum forward CG)
Angle of Attack Indicators
An AOA indicator gives the pilot better situational awareness pertaining to the aerodynamic health of the airfoil. This can be referred
to as stall margin awareness or knowing the existing margin between the current AOA and the critical AOA. While learning to
recognize stalls without relying on stall warning devices is important, an AOA indicator provides an additional visual indication of
the airplane’s proximity to the critical AOA. The FAA along with the General Aviation Joint Steering Committee (GAJSC) is
promoting the use of Angle of Attack (AOA) indicators to reduce the occurrence of loss of control in flight.
Without an AOA indicator, the AOA is “invisible” to pilots. These devices measure several parameters simultaneously and deter mine
the current angle of attack providing a visual image to the pilot of the current AOA along with representation of the proximity to the
critical AOA. These devices can give a visual representation of the energy management state of the airplane. The energy state of an
airplane is the balance between airspeed, altitude, drag, and thrust and represents how efficiently the airfoil is operating. With this
increased situational awareness pertaining to the energy condition of the airplane, the pilot has additional information to help prevent a
loss of control scenario.
AOA indicators are increasingly affordable for GA airplanes. There are several different kinds of AOA indicators with varying
methods for calculating AOA; therefore, proper installation and training on the use of these devices is important. AOA indicators
measure several parameters simultaneously, determine the current AOA, and provide a visual image of the proximity to the critical
AOA. [Figure 5-9] Some AOA indicators also provide aural indications, which can provide awareness to a change in AOA that is
trending towards the critical AOA prior to installed stall warning systems. It’s important to note that some indicators take flap
position into consideration, but not all do.
While AOA indicators provide a simple visual representation of the current AOA and its proximity to the critical AOA, they are not
without their limitations. These limitations should be understood by operators of GA airplanes equipped with these devices. Like
advanced automation such as autopilots and moving maps, the misunderstanding or misuse of the equipment can have disastrous
results. Some items that may limit the effectiveness of an AOA indicator are listed below:
1. Calibration techniques
2. Probes or vanes not being heated
3. The type of indicator itself
4. Flap setting
5. Wing contamination
Figure 5-9. A conceptual representation of an AOA indicator. It is important to become familiar with the equipment installed in a
specific airplane.
Installation of AOA indicators not required by type certification in GA airplanes has been streamlined by the FAA. The FAA
established policy in February 2014 pertaining to non-required AOA systems and how they may be installed as a minor alteration,
depending upon their installation requirements and operational utilization, and the procedures to follow for certification of these
installations. For updated information on this, please reference the FAA website at www.faa.gov.