Upset Prevention and Recovery

Understand and Control Your Airplane in Any Attitude

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Definition of Airplane Upset

Airplane Upset is defined in the “Airplane Upset Recovery Training Aid” (Revision 2, 2008) on Page .vii as follows:

“An airplane in flight unintentionally exceeding the parameters normally experienced in line operations or training:

  • Pitch attitude greater than 25 deg, nose up.
  • Pitch attitude greater than 10 deg, nose down.
  • Bank angle greater than 45 deg.
  • Within the above parameters, but flying at airspeeds inappropriate for the conditions.”

Introduction

Challenges

Upset recovery deals with recovering an airplane from an unusual attitude. This poses several challenges:

  • the pilot may never have been in exactly this particular situation before,
  • the pilot may be struggling with situational awareness at that moment,
  • the airplane the pilot is flying differs likely from the aerobatic trainer in which her/his upset prevention and recovery training (UPRT) has been conducted.

Philosophy of Upset Recovery Training

These challenges make UPRT very different from competition aerobatics training, where the student flies well-choreographed maneuvers always the same, as much in control as possible, and merely imitates the control inputs of her/his instructor for that particular make and model aircraft to be flown in competition. Good UPRT training requires a great deal of theoretical education, in particular in aerodynamics and physics, such that the pilot develops the ability to deal with new situations and can transfer her/his knowledge and skills to a different aircraft. Comparatively little time is spent flying: in the airplane, you only learn muscle memory and the physical sensations of extreme unusual attitudes.

For Flight Instructors

For flight instructors, not only recovery capability from out-of-control situations is desirable, in addition the instructor shall be capable to explain and demonstrate the different physical effects, airplane responses, and required control inputs to the student (jumbled intuition based on having flown for many hours is insufficient to pass on proper knowledge).

Acknowledgement

Our upset prevention and recovery program, as well as our approach to flight training and aeronautical education of pilots in general, which permeates this entire website, was heavily influenced by Bill Crawford’s “Unusual Attitudes and the Aerodynamics of Maneuvering Flight” program, which he based on his experiences flying with test pilots, military pilots, and being an accomplished aerobatic competitor himself. In his unique program, also known as “Flightlab”, Crawford pioneered the approach to use flight test methods as cockpit teaching tools for pilots.

Academic Flight takes this approach to an extreme and makes unrestricted use of test pilot theory, including all the mathematics and physics. We derive as much as possible from first principles (including making our own plots to illustrate concepts), and we teach and encourage our clients to embrace the same, because only then you truly know where things are coming from. However, upon the customer’s request, we gladly remove all the mathematics if desired. Especially the UPRT course presented here can be taught completely without equations if needed, and you will still benefit from our technical background, though be advised that some of the deeper essence of the subject may get lost.

Course Content

  • Academics: Online course or 2 days of in-person academic instruction. 
  • Flight Lab: Four 1-hour flights, 2 hours of preflight/postflight briefings (fulfilled by one of our independent partner instructors and flight schools).

Theory (during Online Course/Academic Part)

A thorough theoretical development is key to a high-quality upset prevention and recovery course. The theory taught in our course includes:

  1. Aerospace Engineering-Grade Terminology and Notation (Labeling of Quantities: Reference Frames, Axes, Velocities, Accelerations, Forces, Moments, Stability and Control Derivatives, etc.)
  2. 2-Dimensional Aerodynamics (Airfoils – infinitely long wings)
  3. 3-Dimensional Aerodynamics (Wings – of finite length)
  4. Geometry and Physics (Reference Frames, Euler Angles, Body Rates, Moment of Inertia, Rotational Physics, Equations of Motion)
  5. Fundamentals of Aircraft Stability and Control (Linearization of Equations of Motion, Stability and Control Derivatives, Flight Test Relationships)
  6. Longitudinal Static Stability (incl. Stick-Fixed and Stick-Free Neutral Points)
  7. Lateral-Directional Static Stability
  8. Maneuvering Stability (Longitudinal, Pull-Ups and Turns; incl. Stick-Fixed and Stick-Free Maneuver Points)
  9. Longitudinal Dynamic Stability (Short Period and Phugoid Modes)
  10. Lateral-Directional Dynamic Stability (Roll Mode, Spiral Mode, Dutch Roll Mode)
  11. Stalls
  12. Roll Coupling (Inertial Coupling, I_xz Effect, Aerodynamic Coupling)
  13. Spins (Phases, Modes, Airplane Certification, History of Spin Research and Examples, Recovery Techniques, Flat Spins vs Accelerated Spins, Sideslip–Bank–Flight-Path-Angle Relation, etc.)
  14. Out-Of-Control Prevention and Recovery Techniques

Practice (during Flight Lab)

Upset recovery instruction would be incomplete if only taught theoretically. After the student has learned what is happening to the aircraft, why it is happening, and what to do about it (control inputs), an in-aircraft component of the training is necessary to achieve quick and correct response by the pilot in an upset emergency. The optional, but highly recommended Flight Lab associated with our UPRT course consists of four flights and two hours of preflight/postflight briefings. A selection of maneuvers for these flights comprises:

Flight 1: Flying Qualities

  1. Longitudinal Dynamic Stability (Short Period, Phugoid)
  2. Lateral-Directional Dynamic Stability (Roll Mode, Spiral Mode, Dutch Roll Mode)
  3. Maneuvering Stability (stability during pull-ups and turns)
  4. Stalls and Stall/Spin Awareness (incl. effect of ailerons and rudder; student practice of botched stall attempts, resulting in spin entry)
  5. Accelerated Stalls (stalls at 45- and 60-degree bank angles with recovery to both wings level and while continuing the turn)
  6. Susceptibility for Departure (stalls from uncoordinated flight, including slipping and skidding turns)
  7. Nose High Stalls and Rolling Recoveries (stalls with 60 degrees nose-high attitude)
  8. Roll Dynamics and Authority (aileron vs rudder effectiveness at different airspeeds (cross-over speed), yaw-roll coupling due to dihedral, etc.)
  9. Optional: Flap-induced, non-convergent phugoid and lateral effect of flaps (if an airplane with flaps and this characteristic is used)
  10. Exploration of flight test techniques and flight test relationships.
  11. Primary control failures (return from flight will be flown with rudder, trim and throttle only, without touching the stick, all the way down to short final).

Flight 2: Inverted Flight

  1. Free-Response Roll (Nose-Level Aileron Roll)
  2. Aileron Roll
  3. Slow Roll
  4. Optional: Barrel Roll
  5. Rudder Roll (illustration of yaw-roll coupling)
  6. Sustained Inverted Flight
  7. Coordinated Inverted Turns
  8. Inverted Stalls
  9. Optional: Inverted Accelerated Stalls
  10. Recovery from Inverted Flight Attitudes (wake turbulence upset: instructor puts airplane in inverted attitudes for student to recover: power-idle, push, roll)
  11. Demonstration of Danger of Pull-Through Recovery (Split-S)
  12. Primary control failures: rudder and aileron hardovers
  13. Return: Start navigating back to the airport inverted (turning inverted flight with realistic distractions)

Flight 3: Spins

  1. Normal Spins (1/2-, 1-, 3-turn spins)
  2. Optional: Competition Spins (well-choreographed, 1.5-turns with vertical downline recovery)
  3. Spin entries from a variety of attitudes, including from accelerated stalls (skidding and slipping turns)
  4. Different correct recovery techniques (PARE, Parke-Mueller-Beggs)
  5. Demonstration of incorrect recovery techniques: (rudder-only, elevator-only, all-controls-free recoveries – Decathlon will not stop spinning with rudder-only recovery)
  6. 6-Turn Spins (to induce physiological disorientation, VOR, etc.)
  7. Accelerated Spins
  8. Optional: Flat Spins
  9. Optional: Inverted Spins and Crossover Spins (recommended to postpone to Flight 4 if done at all)

Flight 4: Out-Of-Control Recoveries and Review

  1. Recovery from Out-Of-Control Situations using the All-Controls-Neutral Method
  2. Contrast All-Controls-Neutral Method to PARE and Parke-Mueller-Beggs (explore at which point it still prevents a spin)

The schedule for Flight 3 is ambitious and can be physiologically very taxing. In addition, for students who have never flown spins before, one spin flight is not enough to learn properly.

Therefore, the spin training will invariably spill into Flight 4. Other maneuvers can also be reviewed. In particular recovery from inverted attitudes (wake turbulence upset) with the power-push-roll method should be revisited.

Other aerobatic maneuvers like loops can be included here as well (as well as during the other flights of the course, as time allows).

Note 1: Much of Flight 1, except for the nose high stalls, can be demonstrated in a Utility Category aircraft approved for intentional spins (while no spins will be performed on this flight, spin departure susceptibility will be  explored). This may be very desirable if the student wishes to explore the flying characteristics of the particular airplane make and model which she/he flies frequently. It also gives the opportunity to explore the effect of flaps, because many aerobatic airplanes do not have any. In fact, we also offer a stand-alone Airplane Stability and Control Course, dedicated to this aspect of the UPRT course.

Note 2: This UPRT course is available in an abbreviated form without spins (i.e. only covering flying qualities, inverted flight, and out-of-control recoveries), comprising only one day of academics and a Flight Lab consisting of 2 flights. Purchasing the Flight Lab without the academic instruction is also possible.

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