Welcome Guest. Sign in or Signup

2 Answers

Mode S Transponder and ADS-B relationship

Asked by: 826 views Aircraft Systems, Commercial Pilot, FAA Regulations, Flight Instructor, General Aviation, Instrument Rating

Mode S transponder is basically a equipment that does the work of Mode C + TCAS(TA+RA) and what I have learned on ADS-B is that the ADS-B out and in is broadcasted and received through UAT antenna. I also noticed that the aircraft must be equipped with WAAS or suitable GPS to get information about position, ground track, speed to broadcast them through UAT.

Now, my question is that, Mode S being able to do the TCAS, does it have any linkage between ADS-B?

Does ADS-B need Mode S transponder in order to broadcast its information and receive nearby traffics ?

 

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

2 Answers



  1. Kris Kortokrax on Jul 31, 2016

    A mode S transponder does not “do the work of Mode C + TCAS.”

    You can satisfy your curiosity by referring to AC 20-131A (which describes TCAS and Mode S transponders), AC 20-165B (which describes ADS-B), AC 91-114A (ADS-B Operations) and AC-120-55C (which discusses TCAS II).

    0 Votes Thumb up 1 Votes Thumb down 1 Votes

  2. Best Answer


    John D Collins on Jul 31, 2016

    Mode S is a type of transponder that supports selective addressing of the transponder. The S comes from the word Selective. ADS-B is based on two technologies, UAT and 1090ES. UAT is an independent system that uses the frequency of 978 MHz. 1090ES is an extension of the mode S transponder that supports ADS-B Out on 1090 MHz.

    +2 Votes Thumb up 2 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.