Rexburg ATC clears TWA 326 to Winton as filed, N2 departure, cli

Rexburg ATC clears TWA 326 to Winton as filed, N2 departure, climb and maintain FLI50 initially, contact 121.6 when _______ , and _______ 2313.

A.on course, squaw

B.airborne, squawk

C.takeoff, time

D.reaching, time

正确答案是B