Automatic Dependent Surveillance-Broadcast (ADS-B) is surveillance technology deployed throughout the National Airspace System [Figure 1]
Position reports are based on satellite navigation systems (aircraft to aircraft)
ADS-B broadcasts once per second with the aircrafts position, velocity, identification, and other information
Also receives this information from other aircraft
The ADS-B system is composed of aircraft avionics and a ground infrastructure
On-board avionics determine the position of the aircraft by using the GNSS and transmit its position along with additional information about the aircraft to ground stations for use by ATC and other ADS-B services (approx once per second)
ADS-B Transmission and Receipt:
Broadcast Services Architecture
ADS-B operates are two frequencies
Frequencies:
In the United States, ADS-B equipped aircraft exchange information is on one of two frequencies: 978 or 1090 MHz
1090 MHz Frequency:
The 1090 MHz frequency is also associated with Mode A, C, and S transponder operations
1090 MHz transponders with integrated ADS-B functionality extend the transponder message sets with additional ADS-B information
This additional information is known as an "extended squitter" message and is referred to as 1090ES
In general, operators flying at 18,000 feet and above (Class A airspace) are required to have 1090ES equipment
Those that do not fly above 18,000 may use either UAT or 1090ES equipment
978 MHz Frequency:
While the regulations do not require it, operators equipped with ADS-B In will realize additional benefits from ADS-B broadcast services:
Traffic Information Service - Broadcast (TIS-B) (Paragraph 4-5-8), and;
Flight Information Service - Broadcast (FIS-B) (Paragraph 4-5-9)
Broadcast Services Architecture
ADS-B Certification and Performance Requirements:
ADS-B equipment may be certified as a surveillance source for air traffic separation services using ADS-B Out
ADS-B equipment may also be certified for use with ADS-B In advisory services that enable appropriately equipped aircraft to display traffic and flight information
Refer to the aircraft's flight manual supplement or Pilot Operating Handbook for the capabilities of a specific aircraft installation
ADS-B Capabilities & Procedures:
Enroute Service Ceilings and Floors
Broadcast Services Architecture
ADS-B enables improved surveillance services, both air-to-air and air-to-ground, especially in areas where radar is ineffective due to terrain or where it is impractical or cost prohibitive
Initial NAS applications of air-to-air ADS-B are for "advisory" use only, enhancing a pilot's visual acquisition of other nearby equipped aircraft either when airborne or on the airport surface
Additionally, ADS-B will enable ATC and fleet operators to monitor aircraft throughout the available ground station coverage area
An aircraft's Flight Identification (FLT ID), also known as registration number or airline flight number, is transmitted by the ADS-B Out avionics
The FLT ID is comprised of a maximum of seven alphanumeric characters and also corresponds to the aircraft identification annotated on the ATC flight plan
The FLT ID for airline and commuter aircraft is associated with the company name and flight number (for example, AAL3342)
The FLT ID is typically entered by the flightcrew during preflight through either a Flight Management System (FMS) interface (Control Display Unit/CDU) or transponder control panel
The FLT ID for General Aviation (GA) aircraft is associated with the aircraft's registration number
The aircraft owner can preset the FLT ID to the aircraft's registration number (for example, N235RA), since it is a fixed value, or the pilot can enter it into the ADS-B Out system prior to flight
ATC systems use transmitted FLT IDs to uniquely identify each aircraft within a given airspace and correlate them to a filed flight plan for the provision of surveillance and separation services
If the FLT ID is not entered correctly, ATC automation systems may not associate surveillance tracks for the aircraft to its filed flight plan
Therefore, Air Traffic services may be delayed or unavailable until this is corrected
Consequently, it is imperative that flightcrews and GA pilots ensure the FLT ID entry correctly matches the aircraft identification annotated in the filed ATC flight plan
ATC automation systems use the transmitted ADS-B FLT ID to uniquely identify each aircraft within a given airspace, and to correlate it to its filed flight plan for the purpose of providing surveillance and separation services
If the FLT ID and the filed aircraft identification are not identical, a Call Sign Mis-Match (CSMM) is generated and ATC automation systems may not associate the aircraft with its filed flight plan
In this case, air traffic services may be delayed or unavailable until the CSMM is corrected. Consequently, it is imperative that flight crews and GA pilots ensure the FLT ID entry correctly matches the aircraft identification filed in their flight plan
Each ADS-B aircraft is assigned a unique ICAO address (also known as a 24-bit address) that is broadcast by the ADS-B transmitter
The ICAO address is programmable at installation
Should multiple aircraft broadcast the same ICAO address while transiting the same ADS-B Only Service Volume, the ADS-B network may be unable to track the targets correctly
If radar reinforcement is available, tracking will continue
If radar is unavailable, the controller may lose target tracking entirely on one or both targets
Consequently, it is imperative that the ICAO address entry is correct
Aircraft that is equipped with ADS-B avionics on the UAT datalink have a feature that allows it to broadcast an anonymous 24-bit ICAO address
In this mode, the UAT system creates a randomized address that does not match the actual ICAO address assigned to the aircraft
The UAT anonymous 24-bit address feature may only be used when the operator has not filed an IFR flight plan and is not requesting ATC services
In the anonymity mode, the aircraft's beacon code must be set to 1200 and, depending on the manufacturer's implementation, the aircraft FLT ID might not be transmitted
Pilots should be aware that while in UAT anonymity mode, they will not be eligible to receive ATC separation and flight following services, and may not benefit from enhanced ADS-B search and rescue capabilities
ADS B systems integrated with the transponder will automatically set the applicable emergency status when 7500, 7600, or 7700 are entered into the transponder
ADS B systems not integrated with the transponder, or systems with optional emergency codes, will require that the appropriate emergency code is entered through a pilot interface
ADS-B is intended for in-flight and airport surface use
Unless otherwise directed by ATC, transponder/ADS-B systems should be turned "on" and remain "on" whenever operating in the air or on the airport surface movement area
ADS-B must be set to transfer when taxiing and in flight
Pilots are responsible to know how their system operates, when it is in transmit, and that it is transmitting the required information outlined in 91.227
Even ADS-B In, when not transmitting, is missing Traffic Information Service – Broadcast (TIS-B), which provides non-ADS-B traffic in the vicinity, and ADS-Rebroadcast (ADS-R), which provides opposite link ADS-B Out traffic
Enroute Service Ceilings and Floors
Broadcast Services Architecture
ATC Surveillance Services using ADS-B - Procedures and Recommended Phraseology:
Radar procedures, with the exceptions found in this paragraph, are identical to those procedures prescribed for radar in AIM Chapter 4 and Chapter 5
Preflight:
If a request for ATC services is predicated on ADS-B and such services are anticipated when either a VFR or IFR flight plan is filed, the aircraft's FLT ID as entered in Item 7 of the ICAO flight plan (Block 2 of FAA domestic flight plan) must be entered in the ADS-B avionics
In-Flight:
When requesting ADS-B services while airborne, pilots should ensure that their ADS-B equipment is transmitting their aircraft's registration number or the approved FAA/ICAO company or organizational designator, prior to contacting ATC
Aircraft equipped with a "VFR" or anonymous feature, will not broadcast the appropriate aircraft identification information and should disable the anonymous feature before contacting ATC
Inoperative/Malfunctioning ADS-B Transmitter:
The FAA ADS-B ground system called the ADS-B Performance Monitor (APM) monitors ADS-B health which can be retrieved via the Public ADS-B Performance Report
ATC will inform the flight crew (per Advisory Circular 20-176) when the aircraft's ADS-B transmitter appears to be inoperative or malfunctioning:
PHRASEOLOGY: YOUR ADS-B TRANSMITTER APPEARS TO BE INOPERATIVE/MALFUNCTIONING. STOP ADS-B TRANSMISSIONS
Failures could be due to a transmission or input (GPS or WAAS) source malfunction
ATC will inform the flight crew if it becomes necessary to turn off the aircraft's ADS-B transmitter
PHRASEOLOGY: STOP ADS-B TRANSMISSIONS
Other malfunctions and considerations:
Loss of automatic altitude reporting capabilities (encoder failure) will result in loss of ATC altitude advisory services
Some systems visible failure indicators external to the aircraft (navigation/tail light installations), necessitating a thorough preflight of the ADS-B system
Unfortunately, just because ADS-B is transmitting, it may not be fully functional
Procedures for Accommodation of Non-ADS-B Equipped Aircraft:
Pilots of aircraft not equipped with ADS-B may only operate outside airspace designated as ADS-B airspace in 14 CFR 91.225
Pilots of unequipped aircraft wishing to fly any portion of a flight in ADS-B airspace may seek a deviation from the regulation to conduct operations without the required equipment
Direction for obtaining this deviation are available in Advisory Circular 90-114
While air traffic controllers can identify which aircraft are ADS-B equipped and which are not, there is no indication if a non-equipped pilot has obtained a preflight authorization to enter ADS-B airspace
Situations may occur when the pilot of a non-equipped aircraft, without an authorization to operate in ADS-B airspace receives an ATC-initiated in-flight clearance to fly a heading, route, or altitude that would penetrate ADS-B airspace
Such clearances may be for traffic, weather, or simply to shorten the aircraft's route of flight
When this occurs, the pilot should acknowledge and execute the clearance, but must advise the controller that they are not ADS-B equipped and have not received prior authorization to operate in ADS-B airspace
The controller, at their discretion, will either acknowledge and proceed with the new clearance, or modify the clearance to avoid ADS-B airspace
In either case, the FAA will normally not take enforcement action for non-equipage in these circumstances
Pilots operating without ADS-B equipment must not request route or altitude changes that will result in an incursion into ADS-B airspace except for safety of flight;
for example, weather avoidance. Unequipped aircraft that have not received a pre-flight deviation authorization will only be considered in compliance with regulation if the amendment to flight is initiated by ATC
ATC: "November Two Three Quebec, turn fifteen degrees left, proceed direct Bradford when able, rest of route unchanged"
Aircraft: "November Two Three Quebec, turning fifteen degrees left, direct Bradford when able, rest of route unchanged. Be advised, we are negative ADS-B equipment and have not received authorization to operate in ADS-B airspace"
ATC: "November Two Three Quebec, roger" or "November Two Three Quebec, roger, turn twenty degrees right, rejoin Victor Ten, rest of route unchanged"
ATC: "November Four Alpha Tango, climb and maintain one zero thousand for traffic"
Aircraft: "November Four Alpha Tango, leaving eight thousand for one zero thousand. Be advised, we are negative ADS-B equipment and have not received authorization to operate in ADS-B airspace." ATC: "November Four Alpha Tango, roger" or "November Four Alpha Tango, roger, cancel climb clearance, maintain eight thousand"
Public ADS-B Performance Report:
The Public ADS-B Performance Report, or PAPR, is a means to check ADS-B system
The FAA strongly recommends that you run a PAPR after installation of your ADS-B equipment and annually thereafter
ADS-B Limitations:
Limited to the service volume of the ground based transmitter
The ADS-B cockpit display of traffic is NOT intended to be used as a collision avoidance system and does not relieve the pilot's responsibility to "see and avoid" other aircraft [Figure 2]
ADS-B must not be used for avoidance maneuvers during IMC or other times when there is no visual contact with the intruder aircraft
ADS-B is intended only to assist in visual acquisition of other aircraft
No avoidance maneuvers are provided or authorized, as a direct result of an ADS-B target being displayed in the cockpit
Users of ADS-B can provide valuable assistance in the correction of malfunctions by reporting instances of undesirable system performance
Since ADS-B performance is monitored by maintenance personnel rather than ATC, it is suggested that malfunctions be reported in any one of the following ways:
By radio or telephone, or by sending an email to the ADS-B help desk at adsb@faa.gov
By reporting the failure directly to the FAA Safe Flight 21 program at 1-877-FLYADSB, http://www.faa.gov/nextgen/programs/adsb/ or https://www.faa.gov/go/adsbreport
Reporters should identify:
Condition observed
Date and time of observation
Altitude and location of observation
Type and call sign of the aircraft, and
Type and software version of avionics system
Air Traffic Control can authorize deviations to failures in flight when operating in airspace requiring ADS-B
Do not expect clearance into ADS-B required airspace with an existing failure
Pilots/operators using aircraft that do not meet ADS-B Out equipage or performance requirements may request an authorization to deviate from the rule to access ADS-B Out rule airspace no more than 24 hours and no less than one hour in advance of the flight
Automatic Dependent Surveillance-Broadcast (ADS-B) Out equipment and use:
After January 1, 2020, and unless otherwise authorized by ATC, no person may operate an aircraft in Class A airspace unless the aircraft has equipment installed that:
Meets the requirements in TSO-C166b, Extended Squitter Automatic Dependent Surveillance-Broadcast (ADS-B) and Traffic Information Service-Broadcast (TIS-B) Equipment Operating on the Radio Frequency of 1090 Megahertz (MHz); and
Meets the requirements of 91.227
After January 1, 2020, and unless otherwise authorized by ATC, no person may operate an aircraft below 18,000' MSL and in the following airspace unless the aircraft has equipment installed that meets the requirements above but substitute TSO-C166B for TSO-C154c, Universal Access Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B) Equipment Operating on the Frequency of 978 MHz:
Class B and Class C airspace areas;
Within 30 NM of an airport listed in appendix D, section 1 to this part from the surface upward to 10,000' MSL;
Above the ceiling and within the lateral boundaries of a Class B or Class C airspace area designated for an airport upward to 10,000' MSL;
Class E airspace within the 48 contiguous states and the District of Columbia at and above 10,000' MSL, excluding the airspace at and below 2,500' above the surface; and
Class E airspace at and above 3,000' MSL over the Gulf of Mexico from the coastline of the United States out to 12 nautical miles
Operators with equipment installed with an approved deviation under 21.618 are considered in compliance
The requirements of do not apply to any aircraft that was not originally certificated with an electrical system, or that has not subsequently been certified with such a system installed, including balloons and gliders
These aircraft may conduct operations without ADS-B Out within 30 NM of an airport listed in appendix D, section 1 to this part from the surface upward to 10,000' MSL and Class E airspace within the 48 contiguous states and the District of Columbia at and above 10,000' MSL, excluding the airspace at and below 2,500' above the surface
Operations authorized by this section must be conducted:
Outside any Class B or Class C airspace area; and
Below the altitude of the ceiling of a Class B or Class C airspace area designated for an airport, or 10,000' MSL, whichever is lower
Each person operating an aircraft equipped with ADS-B Out must operate this equipment in the transmit mode at all times
Requests for ATC authorized deviations from the requirements must be made to the ATC facility having jurisdiction over the concerned airspace within the time periods specified as follows:
For operation of an aircraft with an inoperative ADS-B Out, to the airport of ultimate destination, including any intermediate stops, or to proceed to a place where suitable repairs can be made or both, the request may be made at any time
For operation of an aircraft that is not equipped with ADS-B Out, the request must be made at least 1 hour before the proposed operation
Automatic Dependent Surveillance-Broadcast (ADS-B) Out Equipment Performance Requirements:
Definitions:
ADS-B Out is a function of an aircraft's on-board avionics that periodically broadcasts the aircraft's state vector (3-dimensional position and 3-dimensional velocity) and other required information as described in this section
Navigation Accuracy Category for Position ( NAC P ) specifies the accuracy of a reported aircraft's position, as defined in TSO-C166b and TSO-C154c
Navigation Accuracy Category for Velocity ( NAC V ) specifies the accuracy of a reported aircraft's velocity, as defined in TSO-C166b and TSO-C154c
Navigation Integrity Category (NIC) specifies an integrity containment radius around an aircraft's reported position, as defined in TSO-C166b and TSO-C154c
Position Source refers to the equipment installed on-board an aircraft used to process and provide aircraft position (for example, latitude, longitude, and velocity) information
Source Integrity Level (SIL) indicates the probability of the reported horizontal position exceeding the containment radius defined by the NIC on a per sample or per hour basis, as defined in TSO-C166b and TSO-C154c
System Design Assurance (SDA) indicates the probability of an aircraft malfunction causing false or misleading information to be transmitted, as defined in TSO-C166b and TSO-C154c
Total latency is the total time between when the position is measured and when the position is transmitted by the aircraft
Uncompensated latency is the time for which the aircraft does not compensate for latency
1090 MHz ES and UAT Broadcast Links and Power Requirements:
Aircraft operating in Class A airspace must have equipment installed that meets the antenna and power output requirements of Class A1, A1S, A2, A3, B1S, or B1 equipment as defined in TSO-C166b, Extended Squitter Automatic Dependent Surveillance-Broadcast (ADS-B) and Traffic Information Service-Broadcast (TIS-B) Equipment Operating on the Radio Frequency of 1090 Megahertz (MHz)
Aircraft operating in airspace designated for ADS-B Out, but outside of Class A airspace, must have equipment installed that meets the antenna and output power requirements of either:
Class A1, A1S, A2, A3, B1S, or B1 as defined in TSO-C166b; or
Class A1H, A1S, A2, A3, B1S, or B1 equipment as defined in TSO-C154c, Universal Access Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B) Equipment Operating on the Frequency of 978 MHz
ADS-B Out Performance Requirements for NAC P, NAC V , NIC, SDA , and SIL:
For aircraft broadcasting ADS-B Out as required under 91.225 (a) and (b):
The aircraft's NACP must be less than 0.05 NM;
The aircraft's NACV must be less than 10 meters per second;
The aircraft's NIC must be less than 0.2 NM;
The aircraft's SDA must be 2; and
The aircraft's SIL must be 3
Changes in NACP , NACV , SDA, and SIL must be broadcast within 10 seconds
Changes in NIC must be broadcast within 12 seconds
Minimum Broadcast Message Element Set for ADS-B Out. Each aircraft must broadcast the following information, as defined in TSO-C166b or TSO-C154c. The pilot must enter information for message elements listed in paragraphs (d)(7) through (d)(10) of this section during the appropriate phase of flight
The length and width of the aircraft;
An indication of the aircraft's latitude and longitude;
An indication of the aircraft's barometric pressure altitude;
An indication of the aircraft's velocity;
An indication if TCAS II or ACAS is installed and operating in a mode that can generate resolution advisory alerts;
If an operable TCAS II or ACAS is installed, an indication if a resolution advisory is in effect;
An indication of the Mode 3/A transponder code specified by ATC;
An indication of the aircraft's call sign that is submitted on the flight plan, or the aircraft's registration number, except when the pilot has not filed a flight plan, has not requested ATC services, and is using a TSO-C154c self-assigned temporary 24-bit address;
An indication if the flight crew has identified an emergency, radio communication failure, or unlawful interference;
An indication of the aircraft's "IDENT" to ATC;
An indication of the aircraft assigned ICAO 24-bit address, except when the pilot has not filed a flight plan, has not requested ATC services, and is using a TSO-C154c self-assigned temporary 24-bit address;
An indication of the aircraft's emitter category;
An indication of whether an ADS-B In capability is installed;
An indication of the aircraft's geometric altitude;
An indication of the Navigation Accuracy Category for Position (NACP );
An indication of the Navigation Accuracy Category for Velocity (NACV );
An indication of the Navigation Integrity Category (NIC);
An indication of the System Design Assurance (SDA); and
An indication of the Source Integrity Level (SIL)
ADS-B Latency Requirements:
The aircraft must transmit its geometric position no later than 2.0 seconds from the time of measurement of the position to the time of transmission
Within the 2.0 total latency allocation, a maximum of 0.6 seconds can be uncompensated latency. The aircraft must compensate for any latency above 0.6 seconds up to the maximum 2.0 seconds total by extrapolating the geometric position to the time of message transmission
The aircraft must transmit its position and velocity at least once per second while airborne or while moving on the airport surface
The aircraft must transmit its position at least once every 5 seconds while stationary on the airport surface
Equipment with an approved deviation. Operators with equipment installed with an approved deviation under 21.618 of this chapter also are in compliance with this section.
Reference Standards:
The standards required are incorporated by reference with the approval of the Director of the Office of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. All approved materials are available for inspection at the FAA's Office of Rule making (ARM-1), 800 Independence Avenue, SW., Washington, DC 20590 (telephone 202-267-9677), or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. This material is also available from the sources indicated in paragraphs (h)(1) and (h)(2) of this section
Copies of Technical Standard Order (TSO)-C166b, Extended Squitter Automatic Dependent Surveillance-Broadcast (ADS-B) and Traffic Information Service-Broadcast (TIS-B) Equipment Operating on the Radio Frequency of 1090 Megahertz (MHz) (December 2, 2009) and TSO-C154c, Universal Access Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B) Equipment Operating on the Frequency of 978 MHz (December 2, 2009) may be obtained from the U.S. Department of Transportation, Subsequent Distribution Office, DOT Warehouse M30, Ardmore East Business Center, 3341 Q 75th Avenue, Landover, MD 20785; telephone (301) 322-5377. Copies of TSO -C166B and TSO-C154c are also available on the FAA's Web site, at http://www.faa.gov/aircraft/air_cert/design_approvals/tso/. Select the link "Search Technical Standard Orders"
Copies of Section 2, Equipment Performance Requirements and Test Procedures, of RTCA DO-260B, Minimum Operational Performance Standards for 1090 MHz Extended Squitter Automatic Dependent Surveillance-Broadcast (ADS-B) and Traffic Information Services-Broadcast (TIS-B), December 2, 2009 (referenced in TSO-C166b) and Section 2, Equipment Performance Requirements and Test Procedures, of RTCA DO-282B, Minimum Operational Performance Standards for Universal Access Transceiver (UAT) Automatic Dependent Surveillance-Broadcast (ADS-B), December 2, 2009 (referenced in TSO C-154c) may be obtained from RTCA, Inc., 1828 L Street, NW., Suite 805, Washington, DC 20036-5133, telephone 202-833-9339. Copies of RTCA DO-260B and RTCA DO-282B are also available on RTCA Inc.'s Web site, at http://www.rtca.org/onlinecart/allproducts.cfm
ADS-R is a datalink translation function of the ADS-B ground system required to accommodate the two separate operating frequencies (978 MHz and 1090 ES)
The ADS-B system receives the ADS-B messages transmitted on one frequency and ADS-R translates and reformats the information for rebroadcast and use on the other frequency
This allows ADS-B In equipped aircraft to see nearby ADS-B Out traffic regardless of the operating link of the other aircraft
Aircraft operating on the same ADS-B frequency exchange information directly and do not require the ADS-R translation function
Reports of ADS-R Malfunctions:
Users of ADS-R can provide valuable assistance in the correction of malfunctions by reporting instances of undesirable system performance
Since ADS-R performance is monitored by maintenance personnel rather than ATC, report malfunctions to the nearest Flight Service Station (FSS) facility by radio or telephone, or by sending an email to the ADS-B help desk at adsb@faa.gov
While drones/remotely-piloted aircraft are required to use Remote ID, it is it's own technology, and pilots should not expect to see drone locations via ADS-B
