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.
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:
- A Mode-S Transponder (with Extended Squitter) or a Universal Access Transceiver (UAT)
- A WAAS GPS or a GNSS/SBAS Receiver
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:
- FIS-B (Weather Data)
- TIS-B (Traffic Data)
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:
- Aviation Routine Weather Reports (METAR)
- Aviation Selected Special Weather Reports (SPECI)
- Terminal Area Forecasts (TAF)
- Significant Meteorological Information (SIGMET)
- Airman’s Meteorological Information (AIRMET)
- Pilot Reports (PIREP)
- NEXRAD Reflectivity (Continental United States [CONUS])
- NEXRAD Reflectivity (Regional)
- Notices to Airmen (NOTAM/Flight Data Center [FDC])
- Winds and Temperature Aloft
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.
