Exercise 20 – Illusions Created by Drift

You will be introduced into various illusions that are caused by strong winds in flight. If your instructor teaches this properly, this can actually be one of the more enjoyable lessons as it can be very relaxing and a very different experience.





    Read Exercise 20 from the Flight Training Manual




·       FTM (Flight Training Manual)

·       Aircraft Information Manual/Pilot Operating Handbook (POH)

·       VTA and VNC

·       Canadian Aviation Regulations (CARs)



·       Review how to get to different areas in the practice area.


·       Read exercise 20 in the FTM.


    Be able to answer the following questions:


1)    How would you determine the height of the ground in the practice area?

2)    What illusion is created when flying into the wind?

3)    Explain the dangers that might be caused by this situation (strong headwind) if this illusion is misinterpreted? What if it’s a strong tailwind?

4)    What are some precautions you should take when flying with a strong tailwind in the practice area?

5)    Describe the illusions you should observe when flying at low altitude with strong winds?

6)    What is the lowest altitude we can fly in a non-built up area?

7)   When flying a turn with a constant ground radius in wind, when is the groundspeed the least? What is the relative bank angle at this point?

8)  For a given airspeed, how is the turn radius affected by the angle of bank?



Tips/Rules ofThumb/Theory


·       Check the upper winds before the flight to anticipate what kind of illusions can be expected


·       When you are flying at low altitudes in the circuit, illusions due to drift will be more apparent over the ground.


·       When flying on days with strong winds, cross-reference your instruments! Don’t rely on visual perceptions that you are unsure of (one more reason to do flight instrument check during taxi)


·       If gliding into a strong headwind, increase speed to increase range (due to increased groundspeed).


·       Turbulence may be greater at low levels, so ensure you are strapped in securely.


·       Share your time appropriately between airplane control, maintaining and adjusting the path over the ground, keeping coordinated with rudder pressure and maintaining a visual scan to avoid other aircraft and objects. 

All of this information on pilot training and flight training in Canada is also available at www.myflighttraining.ca.