All Sorts of Stalls
You won't have to learn many of these, but your instructor will
By Ken Medley
All your study of stalls to this point has probably been focused on power-on and power-off stalls. Did you know that there are three other types of stalls that would-be CFIs must be able to perform? While they are found only in the practical test standards (PTS) for flight instructors, in the interest of safety, pilots in general would be wise to learn about these maneuvers. Here's some information on all five stall types.
Power-on stalls are sometimes not fully understood, particularly in the case of high-performance aircraft. Some instructors have the impression that full throttle is required, but it is not. Using climb power, especially in multiengine and high-performance airplanes, can result in excessively high pitch attitudes and make recovery difficult.
In high-performance airplanes, the power setting for power-on stalls may be reduced to no less than 55 to 60 percent of full power so that the stall can be achieved with pitch no higher than 20 degrees. The objective of the maneuver is to identify the stall rather than to stand the airplane on its tail. Private pilot candidates announce the buffeting or decay of control effectiveness and recover promptly after the stall occurs by decreasing pitch attitude and applying appropriate power for returning to level flight with a minimum loss of altitude.
For power-off stalls, the private pilot applicant establishes a stabilized glide in the landing configuration with a gear and flap setting as specified by the examiner. The applicant lifts the nose and announces indications of buffeting or decay of control effectiveness and recovers promptly after the stall occurs with minimum altitude loss.
The three other stalls listed in the flight instructor PTS are crossed-control stalls, elevator trim stalls, and secondary stalls. Demonstration stalls are not required to a level of proficiency. The reason there is no set proficiency level is the unexpected nature of what might happen, depending on the characteristics of the airplane being used. Instructors are expected to teach pilots the hazards of these stalls and measures to prevent them from occurring in the first place.
On the CFI flight test, the applicant will demonstrate at least one of these three additional types of stall. The applicant will explain how a student would be taught the hazards of these stalls and how to avoid them. (See Aviation Flying Handbook, FAA-H-8083-3, Chapter 5.) Instructors should teach these stalls to all students, but students should not practice them, especially not when flying solo.
The crossed-control stall involves moving the ailerons in one direction and rudder in the other. The pilot, turning from base leg to final approach with slow airspeed and controls crossed, risks a stall or spin. This stall is particularly dangerous because of the potential for spin at low altitude. The hazard is overcome by holding appropriate airspeed with good coordination. Avoid cross-controlling. This is appropriately demonstrated at an altitude of 3,000 feet agl or higher.
The elevator-trim stall may be demonstrated by the instructor at altitude by placing the airplane in a gliding approach similar to final approach for landing. The instructor trims for landing to achieve a hands-off glide and then applies go-around power, allowing the nose to rise until the critical angle of attack is reached. The nose will be dangerously high. The speed will slow quickly as the airplane reaches a pitch attitude that is obviously too high. As the stall angle of attack is reached, the instructor will recover to level flight by reducing the angle of attack and adjusting power for level flight with minimum loss of altitude. This simulates what can happen on a go-around procedure.
The instructor now turns the controls over to the pilot, and the student is told to advance to full throttle. The nose of the airplane will start to rise. However, the pilot is instructed to hold forward pressure on the stick or yoke to prevent the nose from rising above a normal climb. Forward pressure will be extreme. The pilot should experience how much forward pressure is required to prevent excessive pitch.
The objective is to avoid an excessively high pitch by pressing the control forward. The instructor now instructs the pilot to recover by lowering the nose to level flight, raising the flaps, and adjusting the trim for normal flight with minimum loss of altitude. The purpose of this exercise is to illustrate the hazards of go-arounds and demonstrate the appropriate preventive measure.
The third stall type, the secondary stall, may occur after recovering too abruptly from a previous primary stall. This can happen during initial climb after takeoff or during a go-around procedure. It may be demonstrated with quick back pressure just after a stall occurs. You can demonstrate this during a glide or steep turn. A secondary stall may also occur during spin recovery.
Accelerated maneuver stall
Although not required by the CFI test, the accelerated maneuver stall is worth mentioning. All stalls are the result of an excessively high angle of attack, regardless of speed. Accelerated stalls may occur at any indicated airspeed when excessive back elevator pressure is applied. To recover, simply reduce back pressure.
It's important that flight instructors teach their students about the hazards of all of these stalls. If you understand the situations in which these stalls may occur, recognize the hazards, and know how to recover with a minimum loss of altitude, you'll be a safer pilot.