Summary: RAF film on the tracking and interception of bombers as they approach the United Kingdom at night.
Description: The organisation of a sector operations room and responsibilities of people working there are described and the methods of co-operation between the RAF's squadrons and the Army's searchlight and anti-aircraft gun units are explained. The film illustrates the plotting of raids in the operations room and the use of 'boxes' as a means of allocating responsibility to different units and deciding which should be ordered to intercept a particular raid. Complications, such as those caused by the need for co-ordination with neighbouring sectors, bad weather or particularly bright (FREELANCE) or dark nights, are also discussed. In the latter case the term “CRACKERS” is used to indicate weapons free for Ack-Ack.
