What you need to know
BY 2020, AIRCRAFT OWNERS flying in airspace requiring a Mode-C
transponder will need to equip their aircraft with ADS-B Out.
Having just bought a plane recently—more on that in a future column—I started checking out alternate approaches for complying
with the mandate.
ADS-B stands for automatic dependent surveillance-broadcast. It
is automatic because, unlike a transponder, it broadcasts continuously, not just when interrogated by radar or a traffic collision
avoidance system (TCAS). It is dependent, since it relies on GPS
information. It provides the same surveillance function as radar, but
Tra ffi c / W eather
Traffic / Weather
does so by broadcasting its position.
There are two ADS-B capabilities. ADS-B
Out, the only one mandated by the new rule,
refers to an aircraft broadcasting its position
and other information. Unfortunately,
equipping aircraft with ADS-B Out will cost
thousands but not yield any new benefits.
Owners can elect to also equip with ADS-B
In, which allows an aircraft to receive traffic
information from other ADS-B-equipped
ADS-B Ground Station
(relay between 109OES and 978 UAT)
ADS-B Out equipped aircraft determine their position using GPS (red arrows) and broadcast position data (yellow lines) to similarly equipped ADS-B aircraft and to
ADS-B ground stations. ADS-B ground stations uplink traffic threats (yellow lines) to aircraft equipped with both ADS-B In and Out and traffic and weather data to
aircraft that use 978 UAT for ADS-B.