A radio signal tells the pilot of an airplane when his plane is off the beam.
A radio signal tells the pilot of an airplane when his plane is off the beam.
飞机脱离航道时，会有一个无线电信号告诉驾驶员。
A radio signal tells the pilot of an airplane when his plane is off the beam.
飞机脱离航道时，会有一个无线电信号告诉驾驶员。