- Air Components: Each aircraft equipped with ADS-B technology will have the position of the aircraft determined using GPS and, along with additional information about the aircraft, transmit that information to “whoever is listening.” This not only consists of the ground components but other aircraft or services listening on the appropriate frequency. In the US, those frequencies are 978 and 1090 MHz. The only regulatory requirement for ADS-B is this “Out” portion of the system. Translated, whether you use the rest of the technology, the only thing that your aircraft is required to do is to transmit data OUT.
- Why the two frequencies? The 978 MHz frequency is a US-Only authorized frequency for what is referred to as a Universal Access Transceiver. It is effective only up to 17,999 ft. Above that, you will need the 1090 MHz system. This is what is also referred to as 1090ES (ES meaning Extended Squitter). The easy way to think about this is that a 1090ES system will require the replacement of the entire transponder while the 978 systems can typically integrate with the avionics that are already in the aircraft. For most of GA, this is sufficient. It becomes more complicated if you want to leave the country but for me, when I leave the country I typically turn off my transponder altogether and fly just above the coyotes so as to avoid detection by the… wait, I’ve said too much.
- Ground Components: The FAA ground stations take all of this data that is being sent from the thousands of airborne aircraft and process it. They send it all over the place, to ATC, as well as any aircraft capable of ADS-B IN. The exciting thing that many of you have already experienced is the information sent from these ground stations to your ADS-B In receiver. There are two technologies with ADS-B In, TIS-B and FIS-B.
- TIS-B: Traffic Information Service is a product that provides you with a display of other traffic nearby. Of course, the benefits of increasing your situational awareness are apparent, there are some shortfalls. Since the service takes data from both RADAR and ADS-B to broadcast to you and because of the difference in refresh rates of RADAR (3-13 sec) vs ADS-B (1 sec), you may see your own aircraft as a target on the display. Let’s be honest, who hasn’t had that traffic call, “zero miles, same altitude” and started flipping out while looking for the invisible target.
- FIS-B: Flight Information Service includes weather and other critical aviation information. This is very similar to the XM Satellite weather with additional products. Many weather products (METARs, TAFs, etc.) as well as TFRs, AIRMETS, SIGMETS, PIREPs and NOTAMs are included in the broadcast. This can be a big game-changer when you can see newly formed TFRs around a wildfire or that weather closing in at your destination, requiring a new plan and possible diversion to an alternate. And with the removal of HIWAS, this becomes even more important for our en-route phase of flight.
- 91.225: This new regulation details the equipment and its usage. The first item of note is the very clear language referencing the deadline and airspace.
- (a) After January 1, 2020, and unless otherwise authorized by ATC, no person may operate an aircraft in Class A airspace unless the aircraft has equipment installed that—
- (b) After January 1, 2020, and unless otherwise authorized by ATC, no person may operate an aircraft below 18,000 feet MSL and in airspace described in paragraph (d) of this section unless the aircraft has equipment installed that—
- The rest of the regulation goes on to discuss the airspace requirements, exceptions and more. It is worth a read and you can find it here.
- 91.227: This part of the regulation deals with the performance requirements of ADS-B. This is mostly a technical discussion of the requirements for your equipment. If you are an aircraft owner, perhaps you have received a letter from the FAA with some verbiage to the effect that your equipment is garbage, fix it or we’ll filter you from the system. That may be a bit generalized but I think its pretty close (I know, I’ve received one). The most interesting part of this regulation is paragraph (d) detailing the required information to be submitted with each broadcast and specifically, the pilot’s requirements (items 7-10). While most of this will be transparent, it is possible in most cases to change the call sign of an aircraft in whatever ADS-B equipment is being used. I’ve had to make a few corrections to GA aircraft in recent history and there are some instances of ADS-B call signs being, well, creative. Read more about this regulation here.
- AC 90-114A: This Advisory Circular provides a host of information about the technology, its use and some technical aspects of the equipment. It is definitely a worthwhile read and if you can’t find the time, look for a copy in the bathroom at Gibbs and the terminal building. You have nothing but time in there, AmIRight?
Technology is very quickly catching up to aviation and we can view ADS-B as a foundation of technologies that will allow expansion into some pretty amazing stuff. Imagine ATC knowing what flight plan you have entered into your GPS and having the ability to reroute you automatically for TFR’s, weather and more. Think it is all far-fetched? I thought the Jetsons Rosie the Robot and Back to the Future’s talking house was too and now my house knows more about what’s going on in it than I do. And it tells me!