If everyone else has the same sized bubble, keeping them apart is simple – as long as the bubbles don’t touch! To ensure safe separation, Air Traffic and other aircraft could say, “well it must be somewhere in that bubble”. If a compliant ADS-B aircraft transmits a message saying, here is my position, here is how accurate I am and then here is how certain both of these are correct (integrity), it’s as though an imaginary little bubble of airspace can be drawn around the aircraft. This allows more direct routes through busy airspace and ultimately saves time and fuel costs. One of the benefits of ADS-B is that it enables closer separation of aircraft which share the same airspace. They may well be very accurate, but unless they can also transmit with certainty that the data is correct by supplying an integrity value, then they can’t be used for ADS-B. This last piece of information “positional integrity” is more often than not the stumbling block for low end GPS devices. The transmission from an ADS-B device provides information such as altitude, aircraft ID, SPI indication (also known as “ident”), velocity information, GPS height, aircraft category, position and positional integrity. Let’s look at what an ADS-B message actually contains. Many different varieties but are they all good enough for ADS-B? Now, let’s think of the same scenario for GA! Firstly, not everyone has a GPS, and secondly the GPS engines available for GA range from handhelds through to moving map displays with integrated WAAS GPS. GPS is the technology of choice in aviation to work out your position and when large transatlantic passenger jets use their highly sophisticated GPS to supply positional data to an ADS-B transmitter no problem. That means basically you will need two things, something to work out your position and then something to report it. So, what is ADS-B?Ī simplified explanation of ADS-B is that instead of ATC working out where you are by using primary and secondary radar systems, an aircraft broadcasts its own position. Traditional SSR technology is becoming outdated and expensive to maintain, new modern surveillance techniques are now being introduced and ADS-B is being mandated across the globe. We take you step by step through an ADS-B install in a MooneyĪutomatic Dependant Surveillance – Broadcast (ADS-B) is not a new technology and whilst it has been around for the last 20 years recently it has started to bubble to the surface, emerging as a relevant topic for the GA pilot.
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