Military Air Traffic operating within the airways, or on Upper Air Routes, is normally controlled by civilian ATC centres, although it will often be co-ordinated by military personnel operating within the sector team. In these circumstances VHF radio frequencies will be used.
Outside Class ‘A’ controlled airspace, and Upper Air Space, military flights are more likely to use Ultra High Frequency (UHF) radio and , in fact, some military aircraft are equipped only with UHF radio equipment.
Military operations are, by definition, subject to a less rigid control system since their operating profiles need to be much more flexible than those of their civilian counterparts. They generally fly at lower levels, at high speed, often in groups, and change level and direction frequently and at short notice. High level military flights - for example, refuelling tankers - are controlled by military controllers at the control centres of London and Scottish in their own military operation room.
Military air traffic which intends to fly in London area of control is required to file a flight plan so that the appropriate clearance can be given.