What Is Space-Based ADS-B

The January 1, 2020, deadline for aircraft to be equipped with ADS-B Out is quickly approaching. With that, many operators are feeling the pressure to properly equip their aircraft so they may continue flying.

Aircraft operating in airspace requiring a Mode C transponder will need to be ADS-B Out-equipped by January 1, 2020. Additionally, ADS-B Out will be required in class E airspace over the Gulf of Mexico, at and above 3,000 feet MSL, or within 12 nautical miles of the United States coast. The controlling regulations for ADS-B are 14 CFR 91.225 and 91.227.

ADS-B Out Basics

Simply put, ADS-B Out-equipped aircraft automatically broadcast (hence the “B”) information once per second to receiving stations on the ground. This transmitted information includes (but is not limited to) a GPS-derived aircraft position, barometric pressure altitude, and aircraft speed and direction. The complete list of information required to be broadcast can be found in 14 CFR 91.227(d).

Through the magic of ground receiving stations and fiber-optic cables, the broadcasted information is routed through the ATC automation systems and – VOILA! – a “blip” appears on the controller’s display; the aircraft is now part of the next-gen airspace modernization movement.

But how does ATC know that the aircraft is ADS-B Out-equipped and what kind of installation is on board? This is done by including the appropriate flight plan filing codes in Item 10 and Item 18 of FAA Form 7233-4, most commonly known as the “flight plan form” (refer to AIM 5-1-9 for detailed instructions on which codes to include in these item numbers).

But Wait, There’s More!

Space-based ADS-B is a technology developed by a company called Aireon that completely blows the lid off radar coverage as it stands today. Currently, less than 30 percent of the world’s airspace is covered by ground stations. With space-based ADS-B, 100-percent global surveillance of air traffic is now possible. Along with this huge improvement in coverage, the position update rate provided by the space-based system is about six times faster than traditional radar.

Fear not, because space-based ADS-B is not a new mandate. Rather, it uses existing ADS-B Out equipment. Specifically, it requires a Mode-S ADS-B transponder (i.e. an extended squitter on 1090 MHz) and an A1-class or higher antenna system. In fact, the pilot won’t know (or even really need to be aware) that their aircraft’s ADS-B Out signal is being received on the space-based system; it is completely seamless from the pilot’s perspective.