A Racal helicopter tracking system which may improve communications during search and rescue missions is currently being evaluated by the British Royal Airforce using a Sea King Mk 3A. The real-time tracking system consists of a Racal Avionics satellite transceiver (STR) and control display navigation unit (CDNU). Racal says that the system increases flight safety by reducing air crew workload by automatically transmitting aircraft present position and other information required by the ground terminal, in this case, the RAF Kinloss rescue co-ordination centre (RCC). \rUnder standard operating procedures, pilots should make 'operations normal' calls at certain intervals during the flight to provide the ground terminal with an update of location and activity. Racal says that its system allows the air crew to better concentrate on the task at hand by making these calls automatically every sixty seconds. Using the system, the ground terminal is constantly aware of aircraft position and intent without having to request or respond to the calls. Message reporting intervals are selected by the ground terminal operator and the airborne system then transmits present position, altitude, velocity and intent automatically at the requested update rates. The real-time display of aircraft position and intent is available on a choice of chart types. \rThe CDNU allows aircrew to view received messages and reply using free text or preformatted messaging via the keypad. An emergency mode causes the aircraft position to be highlighted at the ground terminal along with associated audio alert. The system has the potential to be fully integrated into the IBM/Data Sciences rescue co-ordination system (RCS) which would enable the RCC controller to assess which aircraft is most suitable for the mission.\rLeo Gallagher, commercial director of Racal Avionics, said: "This system is an evolution of our earlier work on the Norwegian modified automatic dependent surveillance programme and in future could be grown to become fully CNS/ATM compliant. It provides a vital capability to those demanding civil and military operators who require an integrated automatic complete package which provides real time flight following, free text messaging and above all safety related services."