Stall Avoidance Training

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Stall avoidance training and pilot evaluations of approach to stall recovery procedures must develop essential habit formations that instill recognition and proper recovery from imminent and full stall situations. Using power as the primary control without a reduction in elevator backpressure while recovering from an approach to stall does not instill habit formation for effective stall avoidance and aircraft upset recovery.

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  • Comment on Stall Avoidance Training by Clark Wilson
    Recently there has been an alarming number of in-flight Loss of Control (LOC) incidents which are similar to the Air France 447 accident. Three years ago a DHC-8 Q400 operated by Colgan Air as Flight 3407 in Buffalo, NY stalled, spun out of control and crashed to the ground killing 50 people. Had the pilot of Flight 3407 pushed rather than pulled on the control yoke in response to a stall warning activation, 50 people may still be alive today. See the NTSB Simulated Video of the Colgan Air Flight Accident.
  • Pulling back on the yoke as in initiating a go-round maneuver should not be trained as the proper response to an approaching stall. When pilots practice recoveries from the approach to a wing stall situation, the training should re-enforce an instinctive and immediate response which is the release of back pressure on the yoke along with an increase in power. This action should ensure an immediate reduction in the angle of attack necessary to avoid a fully developed stall.
    In all full stall upset situations, it is necessary to recover from the stall before applying any other recovery actions. To recover from a full stall condition, the angle of attack must always be reduced well below the stalling angle. Nose-down pitch control must be applied and maintained until the wings are fully unstalled.
  • The training that all pilots should receive in recognizing and recovering from the approach to a stall should instill habit formations that may someday become a life saving experience. Stall avoidance is the best solution, but is not always possible; therefore, pilots must also have the necessary knowledge and skills to recover from an upset condition where an aerodynamic stall has fully developed.
  • A fact is emerging that airline pilots are incorrectly recovering from approaching stalls and fully developed stalls. Airline standard procedures have long dictated that the correct response to a stall warning is pitching-up to a climb attitude and powering out of the approach to stall condition. The emphases has been to recover from an approaching stall with little or no loss of altitude rather than utilizing all resources available to ensure that an approach to stall condition does not develop into an upset condition where loss of control occurs.  
  • ALPA’s Human Factors and Training Group and the Training Council have identified In-Flight Loss of Control (ILOC) as a leading cause of accidents worldwide. The ILOC accident and incident rate has prompted efforts by industry to develop proposed mitigations to address this problem. The mitigations chosen include use of simulators, training devices and other appropriate training platforms, the application of new Upset Recovery Training (URT) methodologies, and enhanced emphasis on aerodynamic academics for pilots.
    Several factors have been recognized as contributing to the rise in ILOC’s. One important fact is that the demographics of new airline pilots have changed steadily and dramatically over the past three decades; as a result, fewer pilots being hired by the airlines have been trained on how to recover from unusual attitudes and upsets. This is so because the number of pilots entering the airlines from the military has decreased significantly. Military pilots obtain significant exposure to abnormal flight environments, usually through training sorties in aerobatic-capable aircraft.  Civilian-trained pilots, conversely, may experience minimal exposure to unusual attitude training and little or no exposure to URT.
    According to the “Airplane Upset Recovery Training Aid” (URTA) an airplane upset is defined as:
    An airplane in flight unintentionally exceeding the parameters normally experienced in line operations or training:
    Pitch attitude greater than 25 degrees, nose up.
    Pitch attitude greater than 10 degrees, nose down.
    Bank angle greater than 45 degrees.
    Within the above parameters, but flying at airspeeds inappropriate for the conditions.
    Research on the performance of airline pilots in actual aircraft upsets shows that the encounter of an upset can induce an overwhelming sensory overload that often prevents a pilot from implementing appropriate control strategies.
    The over-reliance on aircraft automation has also led to an insidious decrease in manual flying skills, which may relate to the difficulty pilots have recovering from an upset event. Although automation, used appropriately, has been a great enhancement to aviation safety, pilots still need to retain the necessary knowledge and skills to manually fly the aircraft. This skill set should be regularly exercised during normal flight operations, as appropriate, to ensure that pilots properly respond to abnormal or emergency situations. In addition, as automation often is employed at various levels in the interface between man and machine, pilots should be exposed to as many various levels of automation as possible during training.
    One area under consideration regarding URT is how the FAA practical test standard for approach-to-stall recovery has historically emphasized minimal loss of altitude. Training to minimize altitude loss can lead to an inappropriate flight control response for an aircraft in an actual aerodynamic stall. Therefore, using this methodology for approach-to-stall recovery training can be classified as “negative” training. While airline pilots need to be trained to recognize and avoid the approach-to-stall condition, they also need to be trained how to appropriately recover from a full aerodynamic stall. This full-stall training should include exposure to all aircraft systems designed to warn of an impending stall and/or aid the pilots in recovering from a stall (i.e. stick shaker, stick pusher, speed tape and low-speed cues, AOA indicators, etc.).
    Further, there has been too little emphasis in initial and recurrent airline pilot training on aerodynamic instruction. Pilots are generally not receiving sufficient academic training in the proper use of primary and secondary flight controls, the aerodynamics of high altitude flight and the aerodynamics of upset recovery specific to the type of aircraft the pilot flies. Too often, airlines incorrectly assume that pilots received this training before they were hired or that that they retain this knowledge received from prior employers or other training organizations. Airlines should implement an enhanced URT program to ensure that their pilots develop and retain the necessary knowledge of aerodynamics necessary to avoid, recognize and recover from upset events.
    The use of Full Flight Simulators (FFS) for unusual attitude training and URT can be an effective tool. However, there are limitations to what can accurately be portrayed in a FFS. The URTA clearly presents how effective training can be accomplished through a combination of academics and appropriate use of FFS. Unfortunately, as this training is not mandated by the regulator, the use of the URTA has been rather limited for this purpose.
    While most FFSs do not accurately replicate flight outside an aircraft’s normal envelope, including a full stall, it is still adequate for unusual attitudes and upset recovery training. To avoid negative training, pilots should be taught that the simulator does not represent the actual flight characteristics outside the normal envelope and that the purpose of the training is to become familiar with recovery techniques and aircraft systems.
    The use of traditional maneuvers-based training to acquire the initial necessary knowledge and skill to avoid, recognize and recover from an in-flight upset is appropriate. However, once the initial knowledge and skill set is attained, instructors should endeavor to have the flight upset training event occur at an unexpected time so that the psychological aspects of the “startle factor” that relate to an actual aircraft upset can be replicated in the synthetic environment to the maximum extent possible.
    Pilots would also benefit from the addition of flight instrumentation that allows the pilot to recognize and recover from upsets in the appropriate manner. For example, the addition of an Angle of Attack (AOA) indicator and a load meter in flight deck displays could be very beneficial to pilots in avoiding, recognizing and recovering an aircraft from an upset. Presently, most flight decks have no direct AOA indicator. In addition there is no load meter to help the pilot to maintain a recovery within the structural limits of the aircraft.
    Finally, instructor pilots must have the knowledge and skills to provide realistic upset recovery training.
    Resolution:
    WHEREAS, ALPA’s Human Factors and Training Group and Training Council have identified In-Flight Loss of Control (ILOC) as one of the leading causes of aircraft accidents worldwide,
    WHEREAS, the trend of ILOC is static or increasing in frequency,
    WHEREAS, numerous international working groups and committees are currently addressing the need to enhance pilot training in the area of Upset Recovery Training, and
    WHEREAS, enhanced and targeted Upset Recovery Training can improve the performance of pilots in avoiding, recognizing and recovering from aircraft upset events,
    THEREFORE BE IT RESOLVED, that the ALPA Administrative Manual, Section 80, Part 5, be amended by adding new paragraph O., as follows:
    In-Flight Loss of Control (ILOC) Training
    ALPA supports the following ILOC training measures:
    Enhanced academic requirements for initial and recurrent pilot training on the aerodynamics of normal flight, approach to stall, impending stall, full stall and abnormal flight conditions, including the appropriate use of primary and secondary flight controls.
    The use of the highest fidelity Full Flight Simulators (FFS), including motion, for the purpose of training pilots in avoidance, recognition and recovery from unusual attitudes and upsets.
    Utilization of the industry-produced “Airplane Upset Recovery Training Aid” as a validated and appropriate guide for upset recovery training and the use of FFS for this purpose.
    A requirement that all applicable aircraft systems be appropriately demonstrated in the specific type training for the purpose of upset recovery training. This includes training to recognize the first onset of a stall, through the development of a stall including use of stick shakers, stick pushers, other warning systems, and other aerodynamic situation indications.
    The implementation of enhanced training for instructors and evaluators on upset recovery training.
    Continued research into practical strategies to enhance pilot training in upset recoveries through improved training methodologies, hardware capabilities (i.e., AOA indicators, load meters) and training platforms (FFS, Flight Simulation Training Device, on-aircraft training). The outcome of such research should be specific and practical guidance to industry in preventing and mitigating the risks of ILOC through enhanced upset recovery training.
  • Stall Avoidance Training

    1. 1. . AERODYNAMIC STALLS In-Flight Loss Of Control (ILOC) as a result of an aerodynamic stall has been one of the most significant causes of fatal Army Fixed-Wing aircraft accidents for many years. Loss of control usually occurs because the aircraft enters a flight regime which is outside its normal envelope, usually, but not always at a high rate, thereby introducing an element of surprise for the flight crew involved. 11/17/13 DAC Clark J Wilson
    2. 2. Purpose Of Stall Avoidance Training • Recognize the symptoms of an approaching stall (such as slow airspeed, sloppy controls and or maneuvering at more than 1G) and instinctively recover. • Instill a habit formation so that a pilot’s reaction to an approaching wing stall is always timely reduction in the angle of attack. 11/17/13 DAC Clark J Wilson
    3. 3. Stall Avoidance A pilot should use all energy resources available, including altitude and power as appropriate to prevent or recover from an approaching stall condition. 11/17/13 DAC Clark J Wilson
    4. 4. Stall/Loss of Control Avoidance Training Aviators should be trained to instinctively recognize and recover from: • Approach to stalls • Fully developed stalls • Stall situations that are unexpected Stall/Loss of Control Training should not emphasize initial stall recovery with a minimum loss of altitude and/or a target pitch attitude but an immediate reduction in the angle of attack. Stall/Loss of Control Training should not be associated the with the “Go-Around” maneuver . 11/17/13 DAC Clark J Wilson
    5. 5. The Aerodynamic Stall STALL: AN ABRUPT, but not always abrupt, LOSS OF LIFT AND INCREASE IN DRAG THAT OCCURS WHEN AN AIRFOIL EXCEEDS ITS CRITICAL ANGLE OF ATTACK (AOA) WHICH IS ABOUT 18º to 22º AOA. BASIC PRINCIPLES: • • • • • BOUNDARY LAYER LAMINAR FLOW TRANSITION REGION TURBULENT LAYER SEPARATION ANGLE OF ATTACK (AOA) RELATIVE WIND CRITICAL AOA WING TWIST: • • • • 11/17/13 18º ROOT TO TIP RELATIV E WIND STALL BUILDS INSIDE OUT ( MCA) MAINTAIN AILERON EFFECTIVENESS DAC Clark J Wilson
    6. 6. Airplane Wing Stall View: Airplane Stalls, King Video 11/17/13 DAC Clark J Wilson
    7. 7. Approach to Stall vs. Full Stall 11/17/13 DAC Clark J Wilson
    8. 8. An airplane wing can be stalled at Any: • Airspeed • Altitude • Attitude (Pitch Attitude in relation to the horizon has no relationship to the aerodynamic stall) Given an airplane with the same weight, configuration and G loading, the Indicated Air Speed (IAS) at which a stalls occurs remains constant regardless of True Air Speed (effects of pressure altitude and temperature) 11/17/13 DAC Clark J Wilson
    9. 9. Wing stalls typically occur following : • Speed reduction • Premature flap retraction • Increased wing loading (G) Stalls can be aggravated by Ice contaminated wing surfaces. 11/17/13 DAC Clark J Wilson
    10. 10. Approach to Stall or Stall Recovery • • • • • • A Preventive actions must (ideally) be taken before the stall warning. An approach to a stall is a controlled flight condition. A fully developed stall is an out-of-control, but usually recoverable condition. The recovery procedure for both the approach to a stall and the fully developed stall should be an immediate reduction in angleof-attack. Most full stall and approach to stall incidents have occurred where there was sufficient altitude available for recovery. Stall incidents that progress into accidents occurred because the crew failed to make a positive recovery when the stall warning occurred resulting in a condition that progressed to a full stall. 11/17/13 DAC Clark J Wilson
    11. 11. Stall Recovery is the Priority. Altitude recovery is secondary to Stall Recovery • The approach to stall recovery should not emphasize “Powering Out” of the approach to stall condition without also releasing back pressure on the elevator control. The “Powering Out” technique may be impracticable at altitude due to thrust available. At near stalled angle of attack, drag is high and available thrust for acceleration could be too slow to effect an optimum recovery. • Do not increase back pressure unless ground contact is imminent. • If a go-around maneuver is to be performed, accelerate until all stall warnings have ceased before pitching to a climb attitude. 11/17/13 DAC Clark J Wilson
    12. 12. Altitude Loss During Stall Recovery There are many variables which could affect the amount of altitude loss encountered in a smooth recovery from an approach to stall. These variables may include, but are not limited to: • • • • • Entry Altitude Bank Angle Aircraft Weight Aircraft Configuration Density Altitude The reduction of angle of attack required to initiate recovery will most likely result in altitude loss. The amount of altitude loss will be affected by the operational environment. Training programs and evaluation standards should not mandate a predetermined value for altitude loss for stall recovery. Proper evaluation criteria should consider the multitude of external and internal variables which affect the recovery altitude. The aircraft manufacturer’s recommended stall recovery techniques and procedures take precedence and should be followed. 11/17/13 DAC Clark J Wilson
    13. 13. The only recovery procedure that is valid for the approach to stall and full stall is to release the back pressure on the control column and simultaneously apply power until a safe airspeed is attained. If stall warnings are still indicated, continue pitching below the level pitch attitude until all stall warnings cease. 11/17/13 DAC Clark J Wilson
    14. 14. Stall Speed Is Increased When Flaps Are Retracted Retracting the flaps prematurely in the RC-12 will reduce lift and increase the indicated stall speed: • Selecting flaps from Full Flaps (100%) to Approach Flaps (40%) – Effects about a 10 Knots increase in stall speed • Selecting flaps from Full Flaps (100%) to Approach Flaps (40%) – Effects about a 10 Knots increase in stall speed Any sudden retraction of flaps at slow speed or during an approach to stall recovery may result in a possible fully developed stall and loss of aircraft control. 11/17/13 DAC Clark J Wilson
    15. 15. FULL STALLS • The successful recovery from a fully developed stall involves a very different technique compared to the recovery from the approach to stall. • Recovery from a full stall without reducing pitch attitude is impossible and will certainly require a significant loss of altitude. 11/17/13 DAC Clark J Wilson
    16. 16. ACCELERATED STALLS • The accelerated stall occurs when an aircraft experiences a load factor (G) higher than 1G, for example while turning or pulling up from a dive. • An aircraft can theoretically be stalled at any speed. An aircraft experiencing a load factor greater than 1G will stall at a higher indicated airspeed speed compared to its wings level, un-accelerated stall speed. 11/17/13 DAC Clark J Wilson
    17. 17. Accelerated Stall In A Turn The higher wing loading in a turn due to the higher centrifugal force causes the aircraft to stall at higher speeds compared to the straight and level stall speed. View: Accelerated stall Video 11/17/13 DAC Clark J Wilson
    18. 18. Deep Stalls • Due to the T-Tail design, C-12 and RC-12 aircraft may not manifest the buffeting, pitching and rolling characteristics that typically indicate a stall condition in other fixed-wing aircraft. • A deep wing stall develops when the angle of attack increases well beyond the wing’s critical stall point, aggravated by the T-tail configuration. • Initially, the T-Tail aircraft’s elevator remains effective even after the wing has stalled because the T-Tail remains above the wing’s wake. 11/17/13 DAC Clark J Wilson
    19. 19. T-TAIL Deep Stall • The elevator remaining effective after the wing has stalled could cause the pilot to inadvertently pitch-up to an even greater Angle of Attack (AOA) and into a deep stall. • In a fully developed deep stall the horizontal tail surfaces becomes buried in the wing’s wake and the elevator may then lose all effectiveness, making it impossible to reduce pitch attitude and break the stall. • In the deep stall regime the enormous increase in drag at low speeds can cause an increasingly descending flight path with no change in pitch attitude which further increases the AOA. • Once the deep stall is fully developed there is no guarantee that recovery may be affected by down-elevator movement and it may be impossible to affect a nose-down pitch attitude to increase airspeed. . 11/17/13 DAC Clark J Wilson
    20. 20. DEEP STALL RECOVERY • The Deep stall is characterized by a level pitch attitude, however, the actual flight path may exceed 45 degrees down and a sink rate of up to 8500 feet per minute. • Deep Stall recovery requires a 10 – 15 degrees nose–down pitch change to brake the stall. Allow airspeed to increase to at least 25 KIAS above stall speed. 11/17/13 DAC Clark J Wilson
    21. 21. Ice Contamination On Wings • Any ice (including frost) adhering to the wing surfaces of an aircraft will significantly increase drag and its stall speed. Ice forming aft of the de-ice boot is especially dangerous. • The Stall Warning System in the C-12 (Stall Horn) normally activates about 5-10 Knots above a stall, but with ice on the wings, the Stall Warning System may not activate before a full stall develops. • With an ice contaminated wing, an abrupt full stall may occur without the typical pre-stall warning, i.e. buffet, pitch–down. A brisk reduction in pitch attitude is required to recover. • When landing with any ice adhering to the wings, “as a rule of thumb”, VREF should be increase by 10 Knots IAS. 11/17/13 DAC Clark J Wilson
    22. 22. APPROACH TO STALL RECOVERY At the first sign an approaching wing stall (Stall Warning Horn, pre-stall airframe buffet, loss of control effectiveness and/or nose pitch-down): 1. Decrease angle of attack by simultaneously: • Reducing Pitch Attitude to a measured amount depending upon proximity to the ground and • Simultaneously Adding Power 2. Maintain coordinated flight. 3. Roll wings level. An airplane in a turn has higher wing loading which increases the stall speed. 4. Increase airspeed well above the stall warning airspeed before retracting flaps. 5. After the recovery is complete, proceed with a Go-Around if required, Missed Approach, Stabilized Approach and Landing or appropriate with the flight regime. 11/17/13 DAC Clark J Wilson
    23. 23. DURING APPROACH TO STALL RECOVERY • Be prepared to manage control forces for required pitch inputs. • An actual stall usually but not always results in a nosedown pitch. Too much forward movement of the control column can produce an excessive nose-down attitude. • As power and airspeed are increased, a pitch-up tendency may be induced. • The GO-Around button may be pressed to set a maximum pitch limit during recovery. 11/17/13 DAC Clark J Wilson
    24. 24. CREW COODINATION PILOT FLYING (P*): 1. Communicate positively at the first indication of a wing stall warning, call: “Stall Warning” 2. Disconnect AUTOPILOT/YAW DAMPER. 3. Decrease angle of attack immediately by: • Releasing back pressure. (DO NOT HOLD OR INCREASE PITCH ATTITUDE UNLESS GROUND CONTACT IS IMMINENT! ) and • Advancing the POWER LEVERS to the maximum allowable power position and call: “Set Power” 5. Roll wings level. 6. Maintain coordinated flight. 7. Do not initially change gear or flap configuration. 11/17/13 DAC Clark J Wilson
    25. 25. MAINTAIN COORDINATED FLIGHT • One wing may drop if the aircraft is in an un-coordinated yaw at the onset of a stall. Adverse yaw could result in a spin unless coordinated flight is maintained by proper rudder control. • When power is applied, a yaw may be induced by one engine spooling-up faster than the other. • Even though excessive aileron pressure may have been applied, a spin should not occur if directional (yaw) control is maintained by a timely application of coordinated rudder pressure. STEP ON THE BALL 11/17/13 DAC Clark J Wilson
    26. 26. CREW COODINATION PILOT FLYING (P*) (Continued): 8. If a Go-Around is to be performed because of a resulting unstable approach situation, retract flaps only when a safe airspeed margin above stall is established: • Call for flaps to be selected from the full down position to the approach position only after accelerating to a safe airspeed (about 10 knots above stall warning speed) and the descent has been stopped. • Retract the landing gear as required when a positive rate of climb call is heard or indicated. • Call for flaps to be selected from the approach position the full-up position at or above Vyse. • Call for “GO-AROUND” Checklist and accomplish a go- around/missed approach if applicable. 9. Otherwise, reestablish appropriate flight regime and configuration. 11/17/13 DAC Clark J Wilson
    27. 27. CREW COORDINATION PILOT NOT FLYING (P): 1. Communicate positively - At the first indication of wing stall warning, call: “Stall Warning”. 2. Offer assistance - Guard the controls and be prepared to assist P* with pitch and power if required. 3. Provide aircraft control advisories - Monitor pitch attitude. If pitch is increasing above 7° nose-up pitch attitude call: “Pitch Down”. 4. Directed assistance - Assist P* in increasing POWER LEVERS to the maximum controllable power position and setting PROPELLER LEVERS to MAX RPM position. 5. Cross-monitor performance by verifying that the airspeed increases. 6. Provide obstacle advisories - Monitor proximity to terrain. 7. Monitor airspeed. If airspeed is decaying close to the stall warning speed: 11/17/13 “Increase Airspeed”.
    28. 28. WARNING • The autopilot should be disconnected when operating in severe icing conditions. The autopilot may mask tactile cues that indicate adverse changes in handling characteristics. • The stall warning horn may be unreliable in icing conditions as an actual aerodynamic wing stall may occur well before the stall warning horn activates. • The stall warning horn normally activates 5 to 10 Knots above the actual stall. A wing contaminated with ice may stall at least 10 knots above the stall speed of a clean wing. • 11/17/13 DAC Clark J Wilson
    29. 29. FULL STALL RECOVERY TRAINING • Recoveries from Full Stall conditions may be performed only in a compatible simulator and is required to be demonstrated only during initial aircraft qualification at USAAVNC, Ft. Rucker, AL. • As a part of all stall avoidance training, IPs should discuss the indications and recovery procedures for Full Wing Stalls, Ice Contaminated Tail-Plane Stalls and Accelerated stalls. • Chapters 8 in the Operator’s Manual addresses full stall and spin recovery techniques. 11/17/13 DAC Clark J Wilson
    30. 30. RC-12 FULL STALL RECOVERY • If a full wing stall occurs, briskly move the control column forward to a nose-down attitude. • Level the airplane after airspeed has increased approximately 25 knots above the stall. AVOID A SECONDARY STALL DURING THE PULL-UP 11/17/13 DAC Clark J Wilson
    31. 31. WING DROP • If one wing drops in a stalled condition, apply up wing rudder to level the wings. • Using ailerons to level wings in a stalled condition may aggravate the stall recovery. 11/17/13 DAC Clark J Wilson
    32. 32. RC-12 SPIN RECOVERY • Power levers – IDLE • Apply full rudder opposite the direction of spin rotation. • Simultaneously with rudder application, push the control wheel forward and neutralize ailerons. • When rotation stops, neutralize rudder. CAUTION – Do not pull out of the resulting dive too abruptly as this could cause excessive wing loads and possible secondary stall. • Pullout of dive by exerting a smooth, steady back pressure on the control wheel, avoiding an accelerated stall and excessive aircraft stress. 11/17/13 DAC Clark J Wilson
    33. 33. Ice Contaminated Tailplane Stall (ICTS) Since the horizontal stabilizer acts to counter the natural nose-down tendency caused by the wing lift moment, the airplane reacts by pitching down—often abruptly—when the tailplane is stalled. There is no evidence that the RC12 is uniquely susceptible to ICTS. Compared to other airplane designs, C-12 airplanes may be less susceptible to ICTS for the following reasons: • In the T-tail configuration, the horizontal stabilizer is above the wing downwash induced higher AOA on the horizontal stabilizer. • The C-12 has a pneumatic deicing system that is effective in removing ice accumulation. That is not to say that the C-12 is immune to ICTS. View the NASA Tailplane Icing Stall Video . This illustrates the differences between the Wing Stall and the ICTS. 11/17/13 DAC Clark J Wilson
    34. 34. Effects of Flaps on Inducing ICTS ICTS typically occurs when flaps are extended to the landing position because: • Flap extension increases the wing airflow downwash angle on the horizontal tailplane thus increasing its negative angle of attack (AOA). • Flap extension also reduces the aircraft angleof-attack (AOA) and increases nose-down pitching moment which requires more tail download, all of which in turn result in an increased negative AOA at the horizontal tailplane. 11/17/13 DAC Clark J Wilson
    35. 35. Flaps and Tailplane AOA 11/17/13 DAC Clark J Wilson
    36. 36. Ice Induced Tailplane Stalls Usually Occur When: • • • • Wing flaps are extended; Engine power is increased; The pilot makes a nose-down control input; The airplane increases speed or encounters gust conditions; or • A combination of these factors with flaps extended. Note: Full flap extension is generally the only case that results in ICTS but this may not be true for all designs, particularly those with closely spaced flap settings. 11/17/13 DAC Clark J Wilson
    37. 37. ICTS Recognition Pilots may sense ICTS or impending ICTS as one or a combination of: • Difficulty to trim in the pitch axis. • Pulsing or buffeting of the longitudinal control; or • Lightening of longitudinal control push force or an increase in pull force necessary to command a new pitch attitude. 11/17/13 DAC Clark J Wilson
    38. 38. WING STALLS AND ICE CONTAMINATED TAILPLANE STALLS (ICTS) HAVE DIFFERENT RECOGNITION CHARACTERISTICS AND REQUIRE DIFFERENT RECOVERY ACTIONS Stall Warning Horn 11/17/13 DAC Clark J Wilson
    39. 39. A PILOT’S INCORRECT REACTION TO STALL WARNING The National Transportation Safety Board (NTSB) determined the probable cause of the Feb. 12, 2009, Colgan Air Flight 3407 crash was the captain’s inappropriate response to an activation of the stick shaker — a clear warning of an imminent stall. NTSB Simulated Video of Colgan Air Flight Accident 11/17/13 DAC Clark J Wilson
    40. 40. Wing Stall vs. ICTS The Colgan Air Flight 3407 accident was the result of the pilot’s inappropriate response to an activation of the stick shaker Stall Warning System. WHY? • Colgan Air pilot training emphasized that a pilot’s reaction to a stall warning event must result in a minimum loss of altitude, achieved by holding positive back pressure on the elevator and “powering out of the stall”. Or… • The pilots may have incorrectly interpreted the activation of the Stall Warning System as an ICTS condition for which the pilot responded with increased back pressure on the elevator and a premature flap retraction which resulted in a fully stalled wing. The bottom line is if the Colgan Air pilot had relieved back pressure rather than pulled on the elevator control, 50 people may still be alive today 11/17/13 DAC Clark J Wilson
    41. 41. Air France Flight 447 • Air France Flight 447 was a scheduled airline flight involving an Airbus A330-200 aircraft that crashed into the Atlantic Ocean on 1 June 2009, killing all 216 passengers and 12 aircrew. • The latest reports from accident investigators state that the aircraft crashed following an aerodynamic stall. • The pilot repeatedly pulled back on the stick, producing a stall, continuing even while the stall warning sounded continuously for 54 seconds. • http://www.youtube.com/watch?v=HSTiax4pvZ4&feature=related • http://www.youtube.com/watch?v=ARybu2kHeZ8&feature=related 11/17/13 DAC Clark J Wilson
    42. 42. 11/17/13 DAC Clark J Wilson
    43. 43. In-flight Loss of Control Avoidance and Upset Recovery Training The Airline Pilots Association (ALPA)’s Human Factors and Training Group and Training Council: • Has identified In-Flight Loss of Control (ILOC) as one of the leading causes of aircraft accidents worldwide and • Has recommended enhanced academic requirements for initial and recurrent pilot training on the aerodynamics of normal flight, approach to stall, impending stall, full stall and abnormal flight conditions, including the appropriate use of primary and secondary flight controls. http://www.apstraining.com/2010/alpa-speaks-on-upset-recoverytraining/ 11/17/13 DAC Clark J Wilson
    44. 44. • As a result of the Air France Flight 447 crash, other recent crashes and the NTSB findings concerning the Colgan air disaster, the FAA has issued an Information For Operators (InFO) and a Safety Alert For Operators (SAFO #10012, DATED: 7/6/10). •The FAA is revising the FAA Practical Test Standards (PTS) for the approach to stall recovery in transport category airplanes. The old standard for the approach to stall recovery that emphasizes pitching to nose-up attitude in order to recover with a minimal loss of altitude is no longer valid. • The industry is now changing the approach to stall recovery to emphasize reducing the angle of attack with the elevator control at the first indication of an impending stall, then increasing power. • Using power levers as the primary control in recovering from the approach to stall is no longer a valid technique. 11/17/13 DAC Clark J Wilson
    45. 45. QUESTIONS? FLY SAFE! 11/17/13 DAC Clark J Wilson

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