Notice Number: NOTC8053
Question: Is the traffic information I receive on my ADS-B In system limited if I am not ADS-B Out equipped?
Answer: The answer is ‘yes.’ ADS-B In is a great capability, but it does have limitations that every pilot should understand. The full capabilities of ADS-B In are only realized when aircraft are properly equipped with ADS-B Out transmitting on either of the two approved frequencies, 1090Mhz or 978Mhz.
ADS-B In systems display targets from three sources: same frequency ADS-B (often called link), different link ADS-B through ADS-B Re-broadcast (ADS-R), and from transponder-only aircraft via Traffic Information System – Broadcast (TIS-B). In order to provide your ADS-B In equipped aircraft with the nearby traffic via ADS-R or TIS-B, the FAA ground system has to “know” about your aircraft and the aircraft around you. Your aircraft has to have a properly functioning ADS-B Out system. For TIS-B, your aircraft must be within airspace where surveillance radar is operating and detecting transponder-only aircraft. Now consider the impact on different configurations.
ADS-B In Only Single or Dual Link: If you are equipped with only ADS-B In (no ADS-B Out) and receiving on a single link, say 978Mhz, you can only expect to see nearby traffic broadcasting ADS-B Out on 978Mhz. If you are equipped with only ADS-B In receiving both links (dual link), you’ll be able to see ADS-B Out aircraft on either link directly. However, unless you are in the vicinity of a properly configured ADS-B Out aircraft, you will not receive ADS-R or TIS-B targets (such information will be tailored for the other aircraft, not for yours).
ADS-B In Single Link and ADS-B Out: If you are equipped with ADS-B Out (either link) and receiving ADS-B In on a single link, you will receive traffic on your receiving link directly from the aircraft. When the FAA ground system can see you, you will also receive traffic information on the other link through ADS-R and nearby transponder-only aircraft via TIS-B.
ADS-B In Dual Link and ADS-B Out: If you are equipped with ADS-B Out (either link) and receiving ADS-B In on both links, you will receive ADS-B Out traffic on both links directly, and when the FAA ground system can see you, nearby transponder-only aircraft via TIS-B.
If you are not equipped with ADS-B Out, you are not benefitting fully from the capabilities of the ADS-B system.
Refer to the Aeronautical Information Manual (Chapter 4, Section 5) for more information on these capabilities. www.faa.gov/air_traffic/publications/