Beechcraft King Air on tarmac

ADS-B Info

Automatic Dependent Surveillance – Broadcast is mandatory in the United States after Dec. 31, 2019 (anywhere Mode-C transponders are currently required).

ADS-B technology is being adopted across the world as safer and more-efficient replacement for radar. In brief, ADS-B is the broadcast of aircraft information including direction, groundspeed, and altitude (used for air traffic control) – allowing for more efficient flight operations, higher situational awareness and allowing for weather updates sent to the cockpit electronically.

As of 2017, The FAA estimated that up to 160,000 general aviation aircraft need to install new equipment to meet the 2020 mandate, and there are limited resources to help aircraft owners become compliant. Butler National Corporation and its aerospace subsidiaries (Avcon Industries and Butler Avionics) created this webpage to assist aircraft owners and operators with installation information to motivate early compliance. Installation of ADS-B “Out” hardware takes time – planning is essential.


About ADS-B

What it is:

ADS-B stands for “Automatic Dependent Surveillance – Broadcast.” Here is what the words really mean:

The system Automatically transmits (sends) GPS location, altitude, ground speed and other data from an aircraft at a set interval, without any interaction from the pilot or otherwise.

The system is Dependent upon transponders and a Global Positioning System (“GPS”, also known as a Satellite-Based Augmentation System “SBAS”) or Navigation System for the information it broadcasts.

The system is used for Surveillance because it provides identification and 3-dimensional tracking of equipped aircraft.

The system installed on each aircraft Broadcasts information to ground stations and other aircraft. The ground stations rebroadcast aircraft and flight information that may be used by pilots on aircraft with ADS-B(In) equipment.

ADS-B Types – “In” and “Out”

ADS-B includes “ADS-B (In)” and “ADS-B (Out)”. These refer to two functions of ADS-B equipment. ADS-B(Out) will be mandatory (in 2020) when the aircraft is operating in airspace that currently requires a Mode-C Transponder. ADS-B(Out) equipment broadcasts the aircraft information to other aircraft and ground stations. ADS-B(In) equipment is not currently required. ADS-B(In) provides pilot-usable flight information, such as advisory weather and traffic information.

What You Need:

ADS-B “Out” technology (required in 2020 as FAA mandated) generally requires two pieces of equipment:

These two components may be combined in a single transponder. “Pairing” is the term that defines the approved interface between a GPS position source and transponder(s). Together, the UAT/Mode-S transponder and WAAS GPS pairing make an aircraft compliant (when properly configured).

ADS-B “In” technology (not required at this time) receives subscription-free advisory information broadcasts:

Pilots may use ADS-B(In) services to receive graphical weather and flight information in the cockpit.

FIS-B Products

Flight Information Service-Broadcast (FIS-B) provides graphical weather and flight information (for advisory use only). FIS-B is accessed by using a 978 MHz Universal Access Receiver and ADS-B “Out” transmission.

The FIS-B set of products includes:

FIS-B information, including weather information, NOTAMs, and TFR areas, are intended only for advisory use for the sole purpose of assisting in long- and near-term planning and decision making. The system lacks sufficient resolution and updating capability necessary for tactical aerial maneuvering around localized weather phenomena. In particular, in extreme scenarios, the oldest weather radar data on the display can be up to 15 to 20 minutes older than the display’s age indication for that weather radar data. Also, FIS-B information must not be used in lieu of a standard preflight briefing.

Aircraft owners should make sure safety assessments are conducted on TIS-B and FIS-B avionics. The equipment should meet the performance requirements of the FAA technical standard order (TSO) to ensure it is compatible with existing FAA FIS-B services and meets minimum performance and quality control standards.

Transponder Frequencies

There are two ADS-B link frequency options: 1090 extended squitter (1090ES) and universal access transceiver (UAT). The 1090ES equipment operates on 1090 MHz and has performance requirements specified in TSO-C166b. The UAT operates on 978 MHz and has performance requirements specified in TSO-C154c. This AC addresses installing equipment meeting the requirements of either TSO. Note: 14 CFR § 91.225 requires 1090ES transponders in Class A airspace (above 18,000 feet MSL)

978 MHz / UAT

Universal Access Transceivers (UAT) transponders operate at 978 MHz and support both FIS-B and TIS-B services. UAT receivers are designed for use in the United States in airspace below 18,000 ft. MSL. To access FIS-B information, an aircraft must be equipped with a UAT/978 MHz receiver. FIS-B and TIS-B information can be shown on cockpit-mounted displays or portable electronic devices (PEDs) such as the iPad.

1090 MHz ES

1090MHz transponders, known as “1090 ES” (“1090 MHz Extended Squitter”), will be required in Class A airspace in the United States after Dec. 31, 2019, and will be the ADS-B standard in many foreign countries. 1090 ES transponders send “Extended Squitter” messages, which include position, time and velocity. Aircraft equipped with 1090 ES transponders typically do not have access to ground-transmitted FIS-B services unless they also contain a UAT receiver.

Regulation Compliance

The FAA Mandate

The FAA Mandate is contained in the Code of Federal Regulations, or CFR. The mandate is located in 14 CFR § 91.225 and § 91.227.

Installation Cost Factors / Considerations

When you bring your aircraft to a shop for installation of ADS-B, the following factors can impact your installation:

Example Installation

Typical ADS-B Installation (Diagram)

View diagram as PDF »


ADS-B Mandates

Canada In Effect ADS-B Out for Preferred Routing
Hong Kong In Effect FL290+
Singapore In Effect FL290+ in specific airways.
Sri Lanka In Effect FL290+ in Colombo TMA
Vietnam In Effect FL290+ in specific airways.
Seychelles In Effect All controlled airspace.
Indonesia In Effect Between FL290 & Fl460 in Jakarta and Ujung Pandang FIRs.
Mexico* In Effect *For flights ≥ 3000ft with in 12nm of the Gulf Coast.
Taiwan 2019-12-31 FL290 & above in Taipei FIR.
United States 2020-01-01 Wherever a Mode-C transponder is currently required.
Colombia 2020-01-01 All Colombian airspace.
Australia 2020-06-07 All aircraft regardless of country of registration.
Europe 2020-06-08 IFR > 5,700kg or >250KTAS cruise.



1. ADS-B — Frequently Asked Questions (FAQs), Federal Aviation Administration.

2. Benefits, Federal Aviation Administration

3. Automatic Dependent Surveillance-Broadcast, Federal Aviation Administration.

4. Advisory Circular No. AC 20-165B, Federal Aviation Administration.

5. Advisory Circular No. AC 20-149B, Federal Aviation Administration.

6. Code of Federal Regulations Title 14 §91.225 and §91.227, Office of the Federal Register.

7. Where is ADS-B Out Required?, Aircraft Owners and Pilots Association.

8. ADS-B Solutions, Butler Avionics.