What is the meaning of the yellow arc on the airspeed indicator?

Question

Question Quiz SPL - Sailplane Pilot License - Aircraft General Knowledge

QuizVDS · Accepted Answer

Flight only in calm weather with no gusts to avoid overload.

QuizVDS · Answer

Cautious use of flaps or brakes to avoid overload.

QuizVDS · Answer

Speed for best glide can be found in this area.

QuizVDS · Answer

Optimum speed while being towed behind aircraft.

Id 136 - SPL - What is the meaning of the yellow arc on the airspeed indicator?