ADS-B in: Do You Need It?

Posted by Katie A. on Apr 15th 2022

So now that we’ve gone over ADS-B Out, we can talk more about ADS-B in.

ADS-B In is the equipment that allows the pilot to read the position reports from other aircraft. It contains Flight Information Service Broadcasts (FIS-B) and Traffic Information Service Broadcasts (TIS-B). It is optional and there are a number of portable ADS-B In Receivers that allow this. In addition to traffic, ADS-B also provides certain weather updates. In flight, the pilot can receive METARs, TAFs, NOTAMs, SIGMETS, Convective SIGMETS, winds and temperatures aloft, PIREPs, Temporary Flight Restrictions (TFR), and special use airspace updates. This is all available over ADS-B frequencies with no subscription required. These are designed for safer flying across the country.

ADS-B operates on two frequencies, 978MHz and 1090MHz. FIS-B is only accessible over the 978MHz frequency. TIS-B is available on both the 978MHz frequency as well as the 1090MHz frequency. One difference between the two is that 978MHz units only work inside the United States. Other countries are starting to require their pilots to install ADS-B equipment as well. Their mandate dictates the pilots must utilize the 1090MHz frequency. The 978MHz frequency units are only authorized up to 18,000 feet. If you fly above this altitude frequently, you will need to install the 1090MHz equipment.

There are two main choices to fulfill the mandate. If you would like only the 978MHz option, you will need a universal access transmitter (UAT), also called a 978UAT. If your aircraft does not have a WAAS-enabled GPS receiver, you will need to add an UAT with integrated WAAS. If you use a 978MHz only transmitter, you could potentially miss out on traffic that is broadcasting via the 1090MHz frequency. Sophisticated transponders are able to transmit on the 1090MHz frequency but receive both the 1090MHz and the 978MHz frequencies. The 1090MHz alternative is an upgraded transponder with Mode S. The 1090ES transponder has an extended squitter for use where the 1090MHz is required.

The 978UAT is generally less expensive. It receives free weather and FIS-B information. The upgraded transponder option would be beneficial because although the equipment is more expensive, the install would probably be less expensive and it upgrades the display rather than supplements it. It provides an integrated solution rather than a separate control unit. It may save time and money in the future if your transponder is already older.

Owners all across the country are struggling to get their aircraft into avionics shops to be ADS-B compliant. The deadline is approaching quickly and it is going to negatively affect the pilots and owners who are choosing not to comply. The FAA believes that ADS-B and Next-Generation (Next-Gen) is going to change the way that aircraft operate in the national airspace system for years to come.