Par 4-1 Page 13 CHAPTER 4. STALL PREVENTION TRAINING AND CHECKING
4-1. GENERAL. This chapter provides specific information for training and checking stall prevention (formerly approach-to-stall), which is required by 14 CFR part 121 appendices E and F. Prevention training provides pilots with the skills to recognize conditions that increase the likelihood of a stall event if not effectively managed. Prevention training must include the operator’s standard operating procedures (SOP) and CRM for proper avoidance techniques and threat mitigation strategies.
4-2. SIMULATOR TRAINING (§ 121.424). Training providers are encouraged to use the highest level FFS available when developing their stall prevention and recovery training curriculums. The primary emphasis is to provide the pilot with the most realistic environment possible during impending stall training and checking. Simulator training can either be maneuver-based or scenario-based; checking should be maneuver-based. Both methods are discussed in detail below.
a. Low Speed Alert. During maneuver-based stall prevention training and checking, pilots should apply the stall recovery at stall warning (see paragraph 1-7), not at a low speed alert or low energy alert (e.g., “airspeed low, airspeed low,” “speed, speed, speed,” or a flashing airspeed warning cue). Initiating the stall recovery at a low airspeed alert in maneuver-based stall prevention training or checking does not satisfy the objective of training or checking the stall recovery procedures. During scenario-based stall prevention training, pilots should return the aircraft to a desired aircraft state if any low airspeed or low energy alert is encountered.
NOTE: Instructors and check pilots must be familiar with the limitations of a particular FSTD and ensure that all pilots undergoing training and checking are aware of these limitations to mitigate negative transfer of training.
b. Maneuver-Based Training. This training focuses on the mastery of an individual task or tasks. Maneuver-based training applies to both prevention and recovery training. It should emphasize the development of the required perception and motor skills to satisfactorily accomplish stall prevention and recovery. Limited emphasis should be placed on decisionmaking skills during maneuver-based training.
(1) Configurations. Maneuver-based training should include impending stalls in the following configurations required by part 121 appendix E and § 121.424:
• Takeoff or maneuvering,
• Clean, and
• Landing.
(2) Conditions. Impending stalls in the above three configurations should be trained using the following conditions, as appropriate:
Par 4-2 Page 14
(a) Level flight and turns using a bank angle of 15 to 30 degrees;
(b) Manual and automated (autopilot and/or autothrottle/autothrust, if installed) flight;
NOTE: It may be difficult to use autothrottle/autothrust during maneuver-based training, since the autothrottle/autothrust is usually disconnected and thrust reduced to idle. However, it is important to teach disconnecting the autopilot and autothrottle/autothrust during stall prevention training and, if the integration of the autoflight systems permit it, to develop scenarios with the autothrottle/autothrust engaged.
(c) Visual and instrument flight conditions;
(d) High altitudes near the airplane’s maximum altitude and low altitudes within 500 feet above ground level (AGL); and
(e) Various weights and CG locations within airplane limitations.
(3) Emphasis Items. The following items should be emphasized during maneuver-based training:
(a) Recovery Procedures.
1. Reducing AOA is the proper way to recover from a stall event. Pilots must accept that reducing the airplane’s AOA will normally result in altitude loss. The amount of altitude loss will be affected by the airplane’s operational environment (e.g., entry altitude, airplane weight, density altitude, bank angle, airplane configuration, etc.). At high altitudes, stall recovery will likely require losing several thousand feet.
2. Declare an emergency if necessary. Do not delay recovery due to degrading airspeed or a stall event to obtain air traffic control (ATC) clearance to a lower altitude.
3. Understanding that early recognition and return of the airplane to a controlled and safe state are the most important factors in surviving stall events. Only after recovering to a safe maneuvering speed and AOA should the pilot focus on establishing an assigned heading, altitude, and airspeed.
4. An abrupt pitch-up or trim change can occur when the autopilot unexpectedly disconnects during a stall event. This dramatic pitch-up or trim change typically adds an unexpected physical challenge to the pilot when trying to reduce AOA. In some airplanes, this may be aggravated by an additional pitch up when the pilot increases thrust during stall recovery.
5. Secondary stall warnings are indicative of a pilot prioritizing minimum loss of altitude over proper stall recovery or flight control inputs that are too aggressive. In some airplanes, depending on AOA representations, it may be difficult to determine the point where the pitch can begin to be increased and a momentary secondary stall warning may be
Par 4-2 Page 15 encountered. A secondary stall warning is acceptable as long as AOA is promptly reduced and the airplane’s limitations are not exceeded.
6. Air carriers should develop stall prevention evaluation strategies that are a direct reflection to the aircraft type. Between different aircraft types and variations of an aircraft type there is a broad range of available airspeed/AOA/energy information to the pilot. Therefore, an evaluation of a stall prevention with an attitude direction indicator (ADI) that has sufficient information to determine the flight envelope (pitch limit indicators, speed tape with low speed awareness, airspeed trend needles) should be more stringent. Obviously with this expectation, the assumption is made that the air carrier's stall training prepares the pilot to interpret this information in low energy states. Conversely, a stall prevention evaluation of a pilot that has limited flight envelope information could allow momentary reactivations of the stall warning after the pilot has reduced the AOA to cease the stall warning and is attempting to return the aircraft to safe flight.
(b) Factors Leading to a Stall Event.
1. How changes to factors such as weight, G loading, CG, bank angle, altitude, and icing affect the handling characteristics and stall speeds of the airplane.
2. Inappropriate use or inadequate monitoring of autoflight modes can be a contributing factor to a stall event. For example, climbing in vertical speed can lead to a stall event when pilots do not notice the airspeed reducing as the altitude increases; whereas, climbing in modes such as indicated airspeed or flight level change can protect against unnoticed deceleration in a climb.
(c) Airplane-Specific Knowledge.
1. Impending stall characteristics for the specific airplane, including buffeting of a severity that may make it difficult to read the instruments.
2. Review of AOA indicators (if installed) or interpretation of other representations of AOA such as pitch-limit indicators or speed display symbology that can assist in stall prevention.
3. Noises associated with stick shakers, autopilot, and autothrottle/autothrust disconnect alarms can cause confusion in the cockpit.
4. The effects of malfunctioning or deferred equipment on stall protection and stick pusher systems.
(d) Altitude Effects.
1. Differences between high and low altitude stalls, pitch rate sensitivity of flight controls (due to lack of aerodynamic damping), and amount of altitude loss required for recovery.
Par 4-2 Page 16
2. Thrust available for recovery, and lack of airflow through engines at high AOA (reinforces reduction of AOA must precede any increase of thrust).
c. Scenario-Based Training (SBT). The goal of SBT is to develop decisionmaking skills relating to stall prevention and recovery during Line-Oriented Flight Training (LOFT). Emphasis should be placed on preventing conditions that may lead to a stall event. SBT would normally be used after a pilot demonstrates proficiency in maneuver-based training and during advanced stages of training, such as upgrade training and recurrent training.
(1) Scenarios. When possible, scenarios should include accident, incident, ASAP, FOQA, and/or ASRS data to provide realistic opportunities to see how threat situations may develop and how they should be managed during line operations. Sample SBT lesson plans are provided in Appendix 3.
(2) Briefing. Pilots should not normally be briefed that they are receiving SBT. The concept is line-oriented flying, which allows the pilots to recognize and manage the expected or unexpected stall threats as they develop during normal operations. However, situations may arise where pilots exhibit excellent stall prevention skills and initiate a recovery prior to the complete unfolding of a scenario. That is the desired objective. In those instances, the instructor has the discretion whether to repeat the scenario and then showing and discussing how the many cues typically cascade as the event progresses. Such explanations can reinforce a pilot’s knowledge and allow sharpening of awareness and prevention skills.
4-3. USING SURPRISE IN TRAINING. Surprise has been a factor in stall incidents and accidents. Although it may be difficult to create surprise in the training environment, if achieved, surprise events may provide a powerful lesson for the crew. The goal of using surprise in training is to provide the crew with a surprise experience to reinforce timely application of the effective recovery technique under potentially confusing circumstances. Considerable care should be used in surprise training to avoid a negative learning experience. Surprise should not be used during checking. Stall prevention training should incorporate event conditions and variables typical of an unintentional stall that are likely to result in surprise due to the unexpected stall development, presentation, and behavior.
4-4. CHECKING PARAMETERS. The check pilot is responsible for establishing the flight conditions associated with the impending stall configuration being checked. The pilot may fly the entry profile but is not being checked on the entry, except for recognition of the deteriorating flight situation. The satisfactory completion of the event is based on the pilot’s timely and proper recognition of the impending stall and then proper application of the stall recovery procedure.
4-5. CHECKING CRITERIA. Checking of prevention, recognition, and recovery from an impending stall should be evaluated on the timely and proper response to the impending stall including effective use of available energy; the criteria should not focus on altitude loss. The check pilot should consider the variables present at the time of the impending stall and their effect on the recovery. Checking criteria are:
Par 4-5 Page 17 (and 18)
• Prompt recognition of impending stall,
• Correct application of the stall recovery procedure, and
• Recovering without exceeding the airplane’s limitations.
NOTE: Training providers should adjust their impending stall checking criteria as appropriate and train their check pilots in these changes. The primary goal of checking should be to evaluate a pilot’s immediate recognition and response to an impending stall and their timely, correct accomplishment of the stall recovery procedure.
4-6. REALISTIC SETTINGS FOR CHECKING. In the FFS, the stall prevention checking module should be maneuver-based with an entry altitude consistent with normal operating environments. The entry parameters, including Weight and Balance (W&B), should be within airplane limitations to ensure adequate performance for recovery from an impending stall.
During checking, the pilot should be checked on recovering from the impending stall.
4-7. DEBRIEFING. Debriefing pilots on their performance in both training and checking is essential. Providing pilots with specific feedback on the recovery procedures including whether recovery control inputs were excessive, insufficient, or had cyclic control reversals will assist pilots in improving their recovery procedures and will also address the implications of G loading differences in simulation. If the recovery exceeds the limitations of the FSTD, instructors must make the pilot aware to avoid negative transfer of training.
Par 5-1 Page 19 (and 20) CHAPTER 5. STALL RECOVERY TRAINING
5-1. GENERAL. This chapter provides specific information for training stall recovery, which is an instructor-guided, hands-on experience of applying the stall recovery procedure for a full stall.
Recovery from a full stall, including stick pusher activation, if equipped, is required by § 121.423, but is not checked.
5-2. FULL STALL TRAINING. Full stall training provides pilots with the hands-on experience of the airplane handling characteristics and cues (e.g., increased buffet, reduced stability and control, and roll off) near and at full stall. The focus of full stall training should be maneuver based. Scenario-based training is better reserved for assessing stall prevention skills.
In addition to providing the full stall experience, the following emphasis items should be highlighted by the instructor:
• Discussion of the objective of increasing the AOA beyond an impending stall to experience full stall characteristics, as these full stall characteristics may be significantly different from those they experienced in flying lighter aircraft in their primary training.
• Differences in flight cues and flight/control characteristics in full stall as compared to cues in stall prevention training. If an aircraft exhibits more than one of the ways a full stall is defined, these conditions should be trained.
• Proper recovery once full stall is identified. If full stall is represented by stick pusher activation, pilots must allow the stick pusher to activate before completing the recovery.
5-3. FULL STALL TRAINING MANEUVER. During training for full stall, the pilot may be asked, for demonstration purposes, to call out some aural and visual indications of the impending stall, but defer response until directed to recover, in order to experience the aircraft’s handling qualities in the full stall regime. Such training provides the pilot with an instructor-guided, hands-on experience of recovering from a full stall. Appendix 4 includes an example of Full Stall Experience Training.
5-4. STICK PUSHER. For airplanes equipped with a stick pusher, stall recovery training includes ground training and practical training in an FFS. It is important for pilots to experience the sudden forward movement of the control yoke/stick during a stick pusher activation. From observations, most instructors state that, regardless of previous academic training, pilots usually resist the stick pusher on their first encounter. Usually, they immediately pull back on the control yoke/stick rather than releasing pressure as they have been taught. Therefore, pilots must receive practical stick pusher training in an FFS to develop the proper response (allowing the pusher to reduce AOA) when confronted with a stick pusher activation. Stick pusher training should be completed as a demonstration/practice exercise, including repetitions, until the pilot’s reaction is to permit the reduction in AOA even at low altitudes. Pilot response to a deliberate activation of the pusher is not a checked maneuver.
Appendix 1 APPENDIX 1. STALL RECOVERY TEMPLATE
1. METHODOLOGY. Airplane manufacturers (Airbus, ATR, Boeing, Bombardier, and Embraer) provided input for the creation of a stall recovery template that provides commonality among various airplanes. The basic steps were identifying airplane differences (e.g., stick pushers, stick shakers, turbojets versus turboprops, wing-mounted engines, tail-mounted engines, fly-by-wire and non-fly-by-wire, etc.), finding the commonalities, and proceeding to find a straightforward and effective stall recovery template. In addition to presenting the recovery steps, the template also provides the rationale for each step of the procedure to enable manufacturers to better determine the applicability to their specific airplane.
2. STALL RECOVERY TEMPLATE. The stall recovery template developed with input from the manufacturers is provided in Table 1, Stall Recovery Template (with Associated Rationale).
Although the procedures should apply to the majority of today’s airplanes, manufacturer recommended procedures may deviate from Table 1 due to specific airplane characteristics.
Specific items, such as configuration changes (e.g., flaps extension), that could be required at a specific point during the recovery procedure are not included in the template, but will be included in a specific procedure for a particular airplane. Manufacturers are expected to deviate from this template if necessary due to airplane operating characteristics. For operators of airplanes without a manufacturer stall recovery procedure, the FAA recommends using the stall recovery template as a reference when developing operator specific stall recovery procedures.
NOTE: Reduction of AOA must be paramount in all stall prevention and recovery procedures. Operators should consult with their airplane manufacturer(s) to ensure they have the proper stall prevention and recovery procedure. Outdated procedures should be updated in accordance with this guidance.
Appendix 1 TABLE 1. STALL RECOVERY TEMPLATE (WITH ASSOCIATED RATIONALE) 1 Autopilot and autothrottle/autothrust……………………Disconnect Rationale While maintaining the attitude of the airplane, disconnect the autopilot and autothrottle/autothrust. Ensure the pitch attitude does not increase when disconnecting the autopilot. This may be very important in out-of-trim situations. Manual control is essential to recovery in all situations. Leaving the autopilot or autothrottle/autothrust connected may result in inadvertent changes or adjustments that may not be easily recognized or appropriate, especially during high workload situations.
2 a) Nose-down pitch control……………..Apply until impending stall indications are eliminated
b) Nose-down pitch trim…….………………………..…….As Needed Rationale a) Reducing the angle of attack is crucial for recovery. This will also address autopilot-induced excessive nose-up trim.
b) If the control column does not provide sufficient response, pitch trim may be necessary. However, excessive use of pitch trim may aggravate the condition, or may result in loss of control or high structural loads.
3 Bank…………………………………………………..……Wings Level Rationale This orients the lift vector for recovery.
4 Thrust…………………………………………….………….As Needed Rationale During a stall recovery, maximum thrust is not always needed. A stall can occur at high thrust or at idle thrust. Therefore, the thrust is to be adjusted accordingly during the recovery. For airplanes with engines installed below the wing, applying maximum thrust may create a strong nose-up pitching moment if airspeed is low. For airplanes with engines mounted above the wings, thrust application creates a helpful pitch-down tendency.
For propeller-driven airplanes, thrust application increases the airflow around the wing, assisting in stall recovery.
5 Speed brakes/Spoilers……….…….…………………………..Retract Rationale This will improve lift and stall margin.
6 Return to the desired flightpath.
Rationale Apply gentle action for recovery to avoid secondary stalls then return to desired flightpath.
Appendix 2 APPENDIX 2. SAMPLE DEMONSTRATIONS
1. Two demonstrations were constructed using the philosophies and concepts described in this AC. The first is an impending stall recovery with only idle thrust available that emphasizes the need to reduce the AOA to recover from a stall. The second is a stick pusher demonstration (if equipped).
2. Training providers are encouraged to develop additional demonstrations to fit their training needs. The examples should be easily tailored to any transport category airplane. The examples given are not intended to be limiting in any way. They are simply provided as a framework for development of a training curriculum.
DEMONSTRATION 1: IMPENDING STALL RECOVERY WITH ONLY IDLE
THRUST AVAILABLE OBJECTIVE The pilot will recover from an impending stall by reducing the AOA without applying thrust.
This demonstration is only intended to show that the airplane will return to controlled flight by simply reducing the AOA.
It does not show the pilot the complete procedure for recovering from an impending stall.
EMPHASIS AREAS • Crew coordination, and
• AOA management.
FFS SETUP
CONSIDERATIONS This demonstration may be completed in any airplane configuration or any altitude that allows a recovery.
DEMONSTRATION
ELEMENTS
• At level flight, reduce thrust to idle.
• Increase AOA to achieve conditions for an impending stall without regard to holding altitude.
• At the impending stall, direct the crew to recover solely by lowering the nose to reduce the AOA.
• The demonstration is performed with idle thrust.
COMPLETION
STANDARDS The instructor will advise the pilot that the maneuver is complete when the pilot understands the need to reduce AOA for stall recovery.
Appendix 2 DEMONSTRATION 2: STICK PUSHER DEMONSTRATION (IF INSTALLED) OBJECTIVE The pilot will allow the stick pusher to reduce the AOA and then perform the correct recovery procedure without resisting the stick pusher.
The pilot understands that stick pusher activation must be relied upon and not overridden. In some airplanes, the stick pusher is an automated control input when the airplane approaches the critical AOA. If not resolved, the condition that activated the stick pusher will lead to an aerodynamic stall and possible loss of control. The pilot should be able to perform the appropriate actions should a stick pusher activation occur.
EMPHASIS AREAS • Recognition.
• Crew coordination.
• AOA management: Allow the pusher to reduce the AOA.
• Audible and visual warnings (environment and airplane cueing).
• Effects of altitude on recovery.
• Demonstrate and re-emphasize all impending stall cues and remind the pilot that in normal circumstances the pilot should recover if any of these cues occur. For the purpose of this demonstration, these cues will be noted but not acted upon to experience the stick pusher activation.
• Crewmember understanding for airplanes equipped with a stick pusher, recommended recovery actions in response to stick pusher activation, including activation when in close proximity to the ground or at cruise altitude.
FFS SET UP
CONSIDERATION This demonstration may be completed in any airplane configuration or any altitude that allows for a recovery.
DEMONSTRATION
ELEMENTS
• In level flight, reduce thrust to idle.
• AOA should be increased to achieve the activation of the stick pusher.
• Review impending stall indications as they occur.
• Upon stick pusher activation, direct the crew to allow the pusher activation and then initiate recovery procedure.
COMPLETION
STANDARDS
• The pilot releases back pressure at pusher activation and allows it to reduce the AOA.
• Recovers to the maneuvering speed appropriate for the airplane’s configuration without exceeding the airplane’s limitations. It is probable that some loss of altitude will occur during the recovery.
• The maneuver is considered complete once a safe speed is achieved and the airplane stabilized in level flight.
• There is no predetermined value for altitude loss, and maintaining altitude during recovery is not required.