SAFA Skysailor Magazine

36 SKY SAILOR November | December 2021 This year we have had two AIRS reports where satellite tracking devices have played a significant role in the outcome. In the first, a highly experienced volbiv pilot on a visit to south-west Tasmania found themselves in strife in our infamous horizontal scrub and activated their Garmin inReach. In the second, more recently, a pilot flying alone in central Australia, impacted terrain in the afternoon and suffered a fractured femur. They were able to contact their partner in Alice Springs via their inReach and were rescued by helicopter a few hours later, just on sunset. When I spoke with the police officer in Alice who had controlled the incident, he raised that although the inReach is a good product, rescues in the Outback in summer are time critical – a person can expire in less than three hours. He pointed out that there is a faster solution that could make all the difference between a successful rescue and a tragedy. Let’s take a look at the satellite-based products that are available, how they work and some of the differences. If you’re out the back of beyond, the odds are that there is no mobile phone coverage, so your GSM-based device will be no use. GNSS, COSPAS-SARSAT, and satellite communication constellations Global Navigation Satellite Systems (GNSS) were developed initially for military purposes – navigation and ordinance (specifically ballistic missile) delivery. The American Global Posi- tioning System (GPS) system is owned and op- erated by the US Space Force. It was launched in 1973 and became fully operational in 1995 with a constellation of 24 satellites. In 1996, President Clinton recognised the importance to civilians and made the system dual purpose. There was, however, a kink called Selective Availability (SA). While military users received the highly accurate positions available, civilian users received a fudged position – you could be typically up to 100 to 300m from where the GPS receiver said you were. For those of us working at sea, it meant GPS was only ever an aid to traditional navigation techniques and anyone relying on it to give an absolute position fix was regarded as a grounding just waiting to happen. SA was switched off on 2 May 2000. Suddenly we could fix our position to within 10m. The Russians developed their GLONASS system at the same time that GPS was being developed, but it was not able to provide complete planet-wide coverage until the mid-2000s. China began operating their Beidou NSS in 2018 and its full deployment was completed in 2020. The European Union launched the Galileo system around 2011, and they presently continue launching satellites into the constellation. Most GPS receiver chips being produced today are able to receive and use signals from all four systems, making for extremely accurate and precise position fixes. In addition, India has commenced launching a system and there are local Space-Based Augmentation Systems (SBAS) available. These consist of one or more satellites in stationary orbit over a region providing localised posi- tioning signals. Sending out an SOS by Iain Clarke – SAFA Safety Management Officer