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ADS BSince 2010 the FAA have been at the forefront of utilising modern electronics and technologies to improve aviation safety, including all of General Aviation. In the United States aircraft operating in almost all airspace {A,B,C,E, Airports etc} will be required to fit the Electronic conspicuity aid Automatic Dependant Surveillance Broadcast [ADS-B] system by 2020. Here in the UK and EASA land we are not far behind and ADS-B trials have already been completed...

So what is all the fuss about?


It's all about Electronic Conspicuity (EC).

Electronic Conspicuity technologies transmit the position of the EC equipped aircraft to other airspace users and ground stations operating compatible equipment. More advanced devices are able to receive, display and alert pilots to other/conflicting traffic.



Most aircraft have transponders fitted which 'SQUAWK' their information when another system interrogates them. ADS-B systems broadcast their data continually around twice a second. In conjunction with an onboard GPS and a transponder an ADS-B device transmits information such as ground speed, heading and, if connected to other instruments, vertical rate, roll angle, magnetic heading etc can also be broadcast.


Now you see me, now you don't

With transponders an aircraft's visibility on radar relies on 'line of sight' and the power and serviceability of the radar system to achieve a successful interrogation and response from the aircraft. In areas where coverage is limited such as over the ocean, parts of Scotland and Wales or visibility is obstructed by terrain an aircraft will simply vanish from a controller's radar screen. Radar systems are expensive and generally located at airports whilst ADS-B towers are a much smaller and a cheaper alternative so greater coverage can be achieved. Satellites are also being equipped with ADS-B allowing complete global surveillance.


The IN and OUT of it

OUT systems broadcast data about the host aircraft for others stations to receive and interpret. IN / OUT systems provide the pilot with a real time picture of the airspace around them. The most basic provide alert/conflict functions of other ADS-B equipped aircraft whilst the more expensive provide a host of data visually either on a portable device with a moving map or a fitted MFD map screen.


Just another gadget with no benefit?
It would seem not.

EC devices turn the traditional ‘see and avoid’ concept into ‘see, BE SEEN, and avoid’. This, in various trials including those in the UK, have demonstrated an overwhelming safety benefit of ADS-B. The reality of flying VFR in Class G airspace with a Flight Information Service is limited to what the air traffic controller can identify on radar, which wouldn't include all air going vehicles such as balloons and gliders, the limited information current transponders provide to ATC and the ATC workload at the time. With such unpredictability pilots flying in Class G are required to 'see and avoid' with all the limitations and flaws the MK1 eyeballs have. With an IN/OUT ADS-B system a pilot can benefit from conflicting traffic alerts, with display systems providing a real time situational awareness of other all ADS-B equipped traffic.


In contrast to the approach taken by the United States and the obvious safety benefits, at present, there is no requirement now or in the future for aircraft flying in the UK or Europe to be fitted with ADS-B. The CAA are however keen to see the widespread voluntary take up of the technology and are therefore working with manufacturers to produce a wide variety of devices based on price and functionality. Low power lightweight devices are being developed for microlights, balloons and gliders and those which will link to other portable devices pilots may already own, such as iPads and uncertified portable GPS systems. Other lower cost options include OUT only systems and utilising / upgrading currently fitted MFD systems.


Despite the 'soft implementation' approach of the CAA and EASA there are rules governing the fitting and use of ADS-B systems which are detailed in CAP1391 [read here]. An EC device that operates using ADS-B at 1090MHz must have a Declaration of Capability and Conformance from the manufacturer before you can legally use it on board an aircraft. The pilot in command of the aircraft is responsible for ensuring that the EC device has a valid declaration. A list of devices which have a Declaration of Capability and Conformance should be available this year [2016].


Airtime avionics engineers are skilled in this area and are able to provide the right solution for your specific requirements.


For further reading please see this technically detailed excellent article by David Chambers on the PPL/IR website please click here


Here are a selection of helpful videos from Avidyne on the subject

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