5、平飞巡航时应定时交叉检查主高度表，正常情况两个主高度表读数差值不应大于？ How much difference between the primary altimeters should be no more than when the flight crew crosscheck the primary altimeters every one hour in level flight cruise?
A.200英尺 200FT;
B.150英尺 150FT;
C.75英尺 75FT;
正确答案是A