Pitch or Angle of Attack

Pilots generally understand that the turn from base to final can result in a stall/spin incident; however, not all pilots fully understand the aerodynamic stall. Many pilots carry extra airspeed in the turn to ameliorate the situation. Other pilots avoid pitching up to avoid a stall during a turn. In either case, the fundamental principle is misrepresented. If the occurrence of LOC accidents are to be reduced, pilots must understand that the pilot’s excessive use of the angle of attack control causes airplanes to stall.
Pilots generally understand that the turn from base to final can result in a stall/spin incident; however, not all pilots fully understand the aerodynamic stall. Many pilots carry extra airspeed in the turn to ameliorate the situation. Other pilots avoid pitching up to avoid a stall during a turn. In either case, the fundamental principle is misrepresented. If the occurrence of LOC accidents are to be reduced, pilots must understand that the pilot’s excessive use of the angle of attack control causes airplanes to stall.
The principles of aerodynamics are complex so pilots use special words to convey meaning and concept important to understanding flying fundamentals. Pilots and flight instructors might assume students and even other pilots understand the meaning of words such as “coordinate”, but maybe not. For example, let’s consider one of aviation’s most fundamental words – “pitch”.

Pitch is defined as an airplane’s rotation on its lateral axis.
• Pitch is not the same as angle of attack.
• Pitch is what the pilot sees with reference to a horizon.
• Angle of attack is what the airplane sees. Angle of attack has no relationship to the horizon.

One of the first concepts learned in pilot school is the aerodynamic stall. When demonstrating and teaching about stalls, flight instructors frequently equate pitch with angle of attack. Query a pilot, a student pilot, and even a CFI about stalls. They will correctly define a stall as exceeding the critical angle of attack. Push them harder and ask, “What does a pilot do to make the airplane stall?

A common response is pitch up. That response derives from the method we use to teach student pilots, and exposes a glaring misunderstanding about aerodynamics. Pitch is not the same as angle of attack.

You can demonstrate that pitch does not equate to angle of attack with a power on stall. If you are unclear about the distinction, try this the next time you fly:
• Establish a climbing flight path and trim for best rate of climb. Reduce power enough to result in declining airspeed.
• Continue the climb with constant pitch.
You must be proactive and increase elevator pressure to hold constant pitch. If you cannot hold a constant sight picture, hold the angle of pitch using reference to attitude indicator.
• As airspeed slows, you will need to increase elevator back pressure, but not enough to increase pitch. Use rudder to control P-factor and keep the wings level.
• Without increasing pitch, the airplane will arrive at the critical angle of attack. Airplane will buffet to announce the unset of a stalled condition.
• At the first unset of buffet, release stick (yoke) and allow airplane’s inherent stability to re-establish the correct angle of attack (function of trim setting) and recover the stall.

During stall recovery resist the temptation to yank, jerk, push or shove the controls – just let go; also, resist the temptation to add power. Additional power is not necessary, and will actually make recovery less comfortable and possibly problematic.

Click here to see this month’s feature video Using the Sight Picture.

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