How should flaps be used during an emergency landing (PPL)? I'm still doing my PPL, but one question has puzzled me recently. During an internal exam before my first solo nav on a C150, the examiner pulled the throttle, so I would do a simulated emergency landing. I chose a field right to me, and with a good gliding speed and without any flaps did a 180 turn (base+final) and found myself flying straight into power lines before the field. We had to go around.

The examiner showed me how it should be done. After the base turn, he deployed flaps 10 and then on final 20. We flew way above the power lines. Now I'm not sure all the altitudes and turning points were the same, but he meant this to show me that I should have used flaps.

My understanding had always been that the use of flaps during emergency landing should be restricted to the final leg from the point that you are certain you will make the airfield. My instructor (not the examiner) had the same view and could not explain it to me.

Any idea?
Specifically in your case you may have lost more altitude in the turn than your instructor or your turns were less coordinated etc. A wide variety of other variables that are hard to note with out accurate course data could have led to your outcome. You would have had to enter the maneuver at the same place/altitude to get similar results and the wind would have an effect here as well. Did you have a head wind or tail wind? Its worth covering some general procedures for this maneuver. 

When turning under glide its important to watch your airspeed and know how the plane will sink in a turn since you sacrifice some lift for the turn. 

Remember flaps allow you to make a steeper approach with out gaining airspeed but what that also means is your ground speed is effected (slowed). 

When it comes to the emergency landing procedure you are free to use flaps at your discretion and as mentioned its generally taught to use them once you are sure you have the field made. If the field is long enough you should shoot for a mid point incase you come up a bit short. Likewise if you are high you can go full flaps and slip it to lose altitude fast (if your instructor has not shown you how to slip a plane to lose altitude I would advise asking him to do so).