All four Cluster satellites will fly independently, controlled by radio contact with a ground station on earth, rather than talking among themselves about where they are.

ECONOMIST: Birds of a feather

Informing ground control on initial contact and indicating an intent to fly the Bay Tour paves the way smoothly for obtaining the Class Bravo clearance to transit through the San Francisco airspace.

FORBES: San Francisco: Up Close And Personal

He did not have a mobile phone and his last contact with the family was by email on 6 January, when he told them of his plans to fly home.

BBC: Tom Armstrong