Today’s podcast is about ADS-B or Automatic Dependent Surveillance-Broadcast.
The FAA has issued a new rule contained in Title 14 of the Code of Federal Regulations Part 91. This rule requires ADS-B Out performance when operating in designated classes of airspace within the US National Airspace System effective January 1, 2020.
Australia already requires ADS-B for operations at or above Flight Level 290. In Hong Kong, ADS-B is required for all operations at or above FL290 on certain airways. In Europe, ADS-B will be required after June 7, 2020 for aircraft over 5700 kilograms and flying faster than 250 knots and on an IFR flight plan. There will be some exemptions for older aircraft in Europe. Mexico has ADS-B rules starting January 1st 2020 as well.
I’ll touch on a few subjects:
- ADS-B in, ADS-B out, and ADS-B NRA, which is non-radar
- System operation/failures and flight planning
- Emergency operations and phraseology as required training elements for ADS-B
- There are other training elements, so speak with your training provider.
Automatic Dependent Surveillance-Broadcast or ADS-B is an automatic datalink that provides transponder and other information through ground stations and satellites, to other aircraft equipped with ADS-B IN.
ADS-B is a surveillance system that relies on aircraft broadcasting their identity, position, and other information to Air Traffic Control. This signal can be captured for surveillance purposes on the ground or on-board other aircraft or vehicles equipped with ADS-B In. ADS-B can greatly improve situational awareness.
Most surveillance systems today use radar to track aircraft. ADS-B is less expensive to deploy and maintain than radar and provides reporting capability where radar is not available, such as oceanic areas. ADS-B also provides air traffic controllers with real-time position information that is more accurate than the information provided by radar-based systems. Because of this, ATC is able to position and separate aircraft with improved precision and timing.
What is the difference between ADS-B IN and ADS-B OUT?
ADS-B IN versus ADS-B OUT can be considered with reference to the aircraft itself. ADS-B OUT is the transmission of ADS-B information from aircraft and ADS-B IN is the receiving of ADS-B information by the aircraft. ADS-B Out is the requirement of the new rule in the US.
ADS-B Out allows aircraft to continuously broadcast data to other aircraft equipped with ADS-B In. ADS-B Out also broadcasts to a network of ground stations that relay the data to ATC.
Data transmitted by an ADS-B Out system could include:
- Aircraft horizontal position
- Horizontal position quality indicators
- Barometric altitude
- Aircraft identification
- A unique ICAO 24-bit aircraft address
- Version number
- Emergency status
- Special Position Indicator or SPI
Okay, let’s talk a bit more about ADS-B In.
ADS-B In capability requires a receiver, a processing system, and a Cockpit Display of Traffic Information, or CDTI. The ADS-B In system can interpret ADS-B Out broadcasts and display traffic and graphical weather information on a display.
ADS-B traffic information is advisory in nature. It is provided only to enhance situational awareness, so ADS-B traffic information should not be relied upon to make evasive maneuvers in IMC.
ADS-B broadcast services include:
- Traffic information broadcast service or TIS-B; and
- Flight information broadcast service or FIS-B.
What is ADS-B-NRA or Non-Radar Area?
The ADS-B NRA application is intended to support ATS in the en-route and terminal environment in areas where radar surveillance does not exist.
Procedures used by ATC for providing separation in non-radar areas are time consuming and inefficient. In areas where radar coverage is not feasible or economically justified, ADS-B-NRA can benefit capacity, efficiency, and safety. ADS-B-NRA separation minima can be less than that of current non-radar airspace, and alerting services can be enhanced by more accurate information on the latest position of aircraft.
Let’s talk operations. (Aircraft Identification and Position Information)
The aircraft identification is inputted into the ADS-B transmit system. This can be accomplished by the FMS, a pilot control panel, or is most likely programmed into the equipment during installation.
A shout out to the NBAA website which always has great information. The NBAA describes a scenario where a crew is planning a trip in the US:
The FAA has an ADS-B Service Availability Prediction Tool or SAPT that anticipates the ability of an aircraft to meet the requirements of Section §91.227 during a particular flight. The prediction tool is designed to be used not more than 24 hours prior to the planned departure. Let’s say the crew confirms that ADS-B will be available for the trip but later determines by NOTAM that service may be interrupted. The operator is responsible for selecting another route or another means to ensure ADS-B service on their trip. This example is specific to the US, so check your regional documentation for differences.
Okay, let’s talk about ADS-B Functionality.
What are the procedures for your aircraft with regards to flight crew input of required ADS-B data? As always, refer to your specific manual.
There are a multitude of possible ADS-B message elements. However, as an example, the Code of Federal Regulations Section 91.227 requires that, “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.”
7 through 10 are the following:
(7) An indication of the Mode 3/A transponder code specified by ATC
(8) 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)
(9) An indication if the flight crew has identified an emergency, radio communication failure, or unlawful interference
(10) An indication of the aircraft’s “IDENT” to ATC
So: transponder code, call sign, emergency status, and an ident for the US.
If the ADS-B avionics system design does not allow for a single point of entry for required information, the applicable manual should be consulted to ensure correct data is present.
The bottom line is that conflicting aircraft identification information must not be transmitted to ATC. Also, if more than one ADS-B transmit system is installed, simultaneous operation of both systems must be prevented.
Let’s talk ADS-B Failures.
Due to the fact that the ADS-B system is automatic and mostly functions without input from the flight crew, there may be limited indication of ADS-B failures. Mode S transponders with ADS-B functionality may indicate a failure such as loss of transponder or ADS-B functionality; however, be aware that input failures such as loss of position source or a GPS/GNSS failure may use the same failure indication. Therefore, it may be a challenge to determine what has actually failed. Solid system knowledge is important, as always.
Here’s an example: Operating in ADS-B required airspace, your left-side GPS becomes invalid. The transponder is set to ‘1’ or ‘a’, meaning the left-side transponder is providing information. There may be an associated alert in your aircraft avionics or checklist, but if there is not, ensure that the transponder selector is positioned to the side with the valid GPS. This will ensure correct location services to the ADS system.
As always, refer to specific manufacturer information to ensure familiarity with device failures and function failures, as well as with the implications and procedures associated with each failure type. Can you fly with a transponder or ADS-B component unserviceable? Have a look at your MEL guidance concerning non-functioning ADS-B equipment.
How does ATC know if you have ADS-B installed?
Basically, two words: Flight Plan
Air traffic systems use REG/ and CODE/ in Field 18 of the ICAO flight plan form to uniquely identify an aircraft and associate it with related capabilities filed in Item 10. The registration mark of the aircraft (REG/) should be filed in Item 18 (an example is: REG/N2567GA) as well as the aircraft address, which is a six-character code (an example is: CODE/A1529D). The FAA’s InFO 15015 has some good information on this.
In item 10 of the ICAO flight plan form, following the NAV suffix, indicate which ADS-B capability is installed on your aircraft by selecting the correct codes. Possibilities can include ADS-B with dedicated 1090 MHz installations, UAT, and VDL mode 4.
Determine from your Aircraft Flight Manual or applicable supplement which coding is appropriate.
Also, the FAA requests in their advisory circular that in the remarks section the flight plan, include the code ‘ADSB’.
There is ADS-B-specific phraseology.
ADS-B phraseology has developed as the technology itself has. ICAO has added the following standard phraseology to Doc 4444: Procedures for Air Navigation Services or PANS to be used by air traffic controllers:
RE-ENTER [ADS-B or MODE S] AIRCRAFT IDENTIFICATION
TRANSMIT ADS-B IDENT
STOP ADS-B TRANSMISSION [SQUAWK (code) ONLY]
TRANSMIT ADS-B ALTITUDE
STOP ADS-B ALTITUDE TRANSMISSION [(WRONG INDICATION, or reason)]
Each aircraft installation is different, so ensure that you are capable of complying with the above requests by referring to your aircraft manual.
Refer to State documents as well for any regional ADS-B specific phraseology. Australia and Canada have their own phraseology.
Let’s talk about surveillance incidents and emergencies.
The ADS-B system can send emergency codes as required (e.g., 7500, 7600 and 7700). The discrete emergency code transmission is entered in the transponder – the same as a transponder without ADS-B capability.
ADS-B State or country procedures may also include the requirement to report surveillance incidents. Reporting methods can differ from country to country, so check what steps are required in the event of a surveillance incident.
I won’t get into it today, but regulators may require training regarding the Human-Machine Interface with respect to ADS-B. Human factors should always be considered with the use of any automation. Speak with your training provider.
So, to summarize, depending on your Regulator, training requirements may include:
- Operating procedures
- MEL procedures
- ADS-B specific phraseology
- Specific systems knowledge
- Flight planning procedures and codes
- Use of ADS-B during emergency procedures
- Data source errors (e.g., a position error due to a GPS failure)
- Incident reporting procedures
- CRM and human-machine interface training
AND… Dependencies of other systems such as GPS and the Flight Management System, and the consequences of their failures on the ADS-B system.
Okay, aviation professionals let’s change gears for a moment. In the News is a segment of the podcast where I talk about other happenings in aviation. I received some feedback about the location of the ‘In the News’ segment, so this episode has the segment at the end of the podcast.
Just last week while flying at Flight Level 380 in the southern US, my flying partner and I were discussing unrelated topics when ATC came on the radio notifying us of an aircraft climbing towards us and cleared to Flight Level 370 as an advisory only. Before the controller could finish his traffic description, our TCAS started talking: TRAFFIC!, yellow filled box on the ND, CLIMB! CLIMB! Without hesitation, the flying pilot disconnected the autopilot and auto throttle and climbed out of the red box displayed on the PFD. The non-flying pilot monitored the flying pilot and called ATC saying we were in a TCAS climb. ADJUST CLIMB was the next instruction we heard, and then CLEAR OF CONFLICT. The flying pilot hand flew a slow descent back to 380 from 385, engaged the autopilot and auto throttle, rebuilt the flight mode annunciator, and monitored the level-off at 380. After we called level, the controller verified we had had an RA. The other aircraft flew past and was cleared to to a higher altitude. We debriefed the event that moment and continued on. I hadn’t experienced an RA in more than 7 years and it’s interesting how one’s training kicks in automatically. Learn more about ACAS/TCAS procedures and training at the TrainingPort.net website.
I hope you enjoyed today’s podcast. I’ll put links in the show notes to the relevant Advisory Circulars. You can also go the TrainingPort.net website for more information on ADS-B training. Have a great day and thanks for listening.
AC 90-114A: Automatic Dependent Surveillance-Broadcast Operations with Change 1
Advisory Circular (AC) No. 700-009