The search and rescue communications channel-past, present and future

From a macroscopic viewpoint, the underlying concept for search and rescue (SAR) involving radio beacons is a communications channel. The communications channel should establish a two-way link by providing confirmation of the message received. The author outlines the different aspects of the SAR communications channel from its very beginnings to the current COSPAS-SARSAT satellite system, and he attempts to predict its evolution into the next century. The first SAR communications channel was instituted with legislation mandating the installation of 121.5-MHz emergency locator transmitters (ELTs) or crash position indicators (CPIs) on all aircraft. Improvements in the communications channel through faster detection of the ELT and better location accuracy were made. The world´s first prototype local user terminal (LUT) was introduced in the late 1970s. This is a satellite receiving station designed explicitly for the SAR communications channel. The LUT itself now detects and locates the beacon transmitter. A global communications network, specifically for SAR data, should eventually emerge