FAA Private Pilot Test Prep

Correct answer: C. 55 to 100 knots. The white arc is the flap safe operating speed. The flaps can be down below the 55 number if the plane needs extra lift on a soft or short field. But, the top number is the most important number in most aircraft as, above this number, damage could occur to the plane. In this case it is 100 knots, the maximum operating speed for flaps.