The increasing use of Identification Friend or Foe (IFF)/Secondary Surveillance Radar
(SSR) systems for both civil and military applications has meant that there is a serious
risk of mutual interference from the uncoordinated installation and operation of
interrogators. If such installations are not carefully controlled, their operation could
have potentially adverse implications for system integrity and hence flight safety.
To minimise the risk and to secure optimum efficiency for secondary surveillance in
its air defence, air traffic radar service and airspace management roles, it is necessary
to exercise control over all interrogator installations regardless of whether they are
static or mobile and operated on land, sea or in the air for whatever function.