Airborne Emergency Location - The Express Route
Barry Thrower, H R Smith Group, Leominster, U.K.
The introduction of the COSPAS - SARSAT satellite system provided a unique global means of conveying important digitally coded information from an activated distress beacon to the Search and Rescue (SAR) authorities, thereby allowing rescue forces to focus their efforts much more accurately than had previously been possible.
Initially, only marine distress transmitters were capable of fully utilising this facility. However, development of compact, light-weight airborne Emergency Locator Transmitters (ELTs) with digital functionality soon followed and satellite-compliant 406 MHz ELTs can now provide essential identification and positional information from an aircraft crash site to aid the rescue.
Notably, however, rescue craft mostly locate and steer onto the distress signal using traditional analogue homing or direction finding technology with its inherent inaccuracies and ambiguities. The development of an airborne Beacon Locator System (BLS) capable of decoding the digital 406 MHz ELT signal was the obvious next step, thereby effectively completing the digital SAR loop. BLS uniquely derives real-time identification and position co-ordinates directly from an activated ELT and provides the SAR crew with clear and unambiguous steering advice.
This holistic approach in developing a fully digital SAR capability has ensured that Express location and rescue is now a reality for both peacetime and combat SAR operations.
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