This became particularly relevant during the second world war when the storms would lead to radio blackouts.

"Break radio blackout and contact the landing party," I ordered.

If there is a total radio blackout, that is also a signal to open the orders.

This dropped as they slowed down, coming out of radio blackout.

We expect radio blackout in two minutes and eleven seconds, seventeen seconds ahead of schedule.

During that venture the spacecraft suffered a brief radio blackout.

'To your positions, men, and radio blackout until you hear from me.'

A 23-day period in 2001 saw 25 flights diverted due to such radio blackouts.

"So far we know nothing about the radiation hazards in the area-and there's always the chance the radio blackout may clear up."

This geomagnetic storm caused a radio blackout over North America.