为避免RVSM空域改平时触发TCAS警告，机组应? What should flight crew do to avoid to trigger TCAS warning when levelling off in RVSM airspace?
A.通过TCAS显示观察相关飞机，自行建立2000英尺的垂直间隔，直到无影响后，再在指定高度层改平 Observe the relevant aircraft through TCAS display,establish 2000ft vertical seperation by oneself,then return to the assigned altitude after no effect
B.脱开自动驾驶，人工柔和改平 Disconnect AP,manually and softly level off the aircraft
C.在接近改平高度层时，减小上升或下降率至500-1000英尺/分钟 Use climb and descent rate of 500-1000ft/min when the distance to designed altitude is 1000ft
正确答案是C