Longitudinal separation based on time for the aircraft flying on crossing track shall be _______ a. 15 minutes；b. 10 minutes if navigation aids permit frequent determination of position and speed.
A.a
B.b
C.a and b
D.a or b
正确答案是D
Longitudinal separation based on time for the aircraft flying on crossing track shall be _______ a. 15 minutes；b. 10 minutes if navigation aids permit frequent determination of position and speed.
A.a
B.b
C.a and b
D.a or b
正确答案是D