11 Jun Drones and ADS-B
Is ADS-B the future of drone safety?
Drones and ADS-B. What is it?
Automatic Dependent Surveillance – Broadcast “ADS-B” is a surveillance technology in which an aircraft determines its position via satellite navigation and rapidly broadcasts it every half-second in Australia on a 1090MHz, digital data link, allowing it to be tracked. The information can be received by air traffic control ground stations as a replacement for secondary surveillance radar, as no interrogation signal is needed from the ground. It can also be received by other aircraft including drones fitted with ADS-B “in” to provide situational awareness and allow self-separation. ADS-B technology has two key components: The first is ADS-B Out, which can be installed in traditional aircraft to determine and broadcast flight information such as flight path, speed, and altitude. The second is ADS-B In, which receives information broadcast from ADS-B Out transmitters. ADS-B has been a gradual roll out over the last decade to ease the burden and provide stronger situational awareness within Australian airspace.
Automatic – Requires no pilot input or external interrogation.
Dependant – Depends on accurate position and velocity data from the aircraft’s navigation system (GPS, static pressure sensors).
Surveillance – Provides aircraft position, altitude, velocity, and other surveillance data to facilities or other aircraft that require the information.
Broadcast – Information is continually broadcast for monitoring by appropriately equipped ground stations or aircraft including increasingly RPAS, UAVs.
ADS-B and Unmanned Aerial Systems
Drone manufacturers and those manufacturing there components are increasingly coming to realise that with exponential numbers of drones in our already congested skies safety must not be compromised. This is why manufacturers such as DJI and Pixhawk are actively future proofing there systems with added safety incorporating ADS-B technology.
Pixhawk manufacturers of flight controllers has recently introduced ADS-B capabilities into there equipment. With this integration, UAS operators will be able to see nearby ADS-B OUT enabled aircraft, notifying the Remote Pilot in Command (RPIC) with timely notification to take the necessary actions to remain well clear.
DJI AirSense is an alert system that uses ADS-B technology to give DJI drone pilots enhanced situational awareness and help them make responsible decisions while flying. This feature gathers flight data sent automatically from nearby aircraft with ADS-B transmitters, analysing it to detect potential collision risks and alert users well in advance through the DJI mobile app. DJI has recently announced that all its drones over 250 grams will be fitted with this technology starting in 2020.
Another way UAS systems are using ADS-B is as redundancy should vital GPS links relied upon be lost. A drone quickly goes from a huge asset to a liability in the blink of an eye if GPS is lost. Researchers at the University of Washington have developed a new system that operates by interrogating an aviation transponder that is carried by the UAS and measuring the time elapsed for the response to multiple, ground-based antenna and using triangulation (multilateration) to locate the transponder and by association, the UAS. The ground-based system then routes this position information back to the UAS via the UAS’s data telemetry link. The autopilot can now utilise this position information for navigation in much the same way it would utilise a GPS-based position
Limitations and Considerations for Unmanned Systems (Drones and ADS-B)
A major factor to be considered in relation to the use of ADS-B to deconflict airspace is that not all manned aircraft are equipped with ADS-B transponders. Back in February 2017, all aircraft operating in Australia under Instrument Flight Rules (IFR) were required to be equipped with 1090 MHz ADS-B transponders. Private aircraft flying IFR procedures in Australian airspace have received an extension to Jan. 1, 2020, to allow more time for installation of ADS-B transponders. However in Australia aircraft flying under Visual Flight Rules (VFR) are not currently required to adopt the technology. An appreciation for the safety benefits ADS-B technology brings is most certainly realised by aircraft operators flying VFR however the adoption of the technology has been slow mostly due to financial constraints of purchasing equipment and installation. Due to this the Civil Aviation Safety Authority (CASA) is proposing to relax the equipment and installation standards for ADS-B fitment in VFR aircraft. These changes would allow for uncertified avionics that meet a minimum standard for ADS-B to be installed. This would enable ADS-B installation to be classed as a minor modification and enable amateur-built and sports aviation aircraft operators to install ADS-B. This would allow for greater awareness for not only manned aircraft to deconflict but also the unmanned world. Irrespective of if this actually occurs unmanned pilots should not be placing 100% reliance in systems such as the DJI Airsense as there is a strong possibility of a non ADS-B equipped aircraft entering the airspace that UAS operations are being conducted and be undetected. In saying that systems such as the DJI Airsense are adding to the safety of aviation improving awareness and will only improve as more and more manned aircraft adopt ADS-B technology.
If looking to incorporate drone operations into your operations please do not hesitate to contact Hover UAV for advice on the best path way forward in achieving such outcomes.