Brown had rigged a wireless set with a 250-mile range. With it, they could check their position and, if they were forced down, spell out an SOS.

• 布朗装了一部有效范围为二百五十英里的无线电收发报机，以便查对他们的位置，还可以在万一被迫降落时发出 sos求援信号。