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AIM 

enter it prior to flight. However, some ADS

−

B avionics require the FLT ID to be set to the aircraft registration 

number (for example, N1234Q) by the installer and cannot be changed by the pilot from the cockpit. In both 

cases, the FLT ID must correspond to the aircraft identification filed in its 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. 

3. 

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. This ICAO address is programmed 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. 

4. 

Aircraft that are equipped with ADS

−

B avionics on the UAT datalink have a feature that allows them 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. 

5. 

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 inflight 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. 

d.  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. 

1. 

Preflight: 

If ATC services are anticipated when either a VFR or IFR flight plan is filed, the aircraft identification (as entered 

in the flight plan) must be entered as the FLT ID in the ADS

−

B avionics. 

2. 

Inflight: 

When requesting surveillance services while airborne, pilots must disable the anonymous feature, if so equipped, 

prior to contacting ATC. Pilots must also ensure that their transmitted ADS

−

B FLT ID matches the aircraft 

identification as entered in their flight plan. 

3. 

Aircraft with an Inoperative/Malfunctioning ADS

−

B Transmitter: 

(a) 

ATC will inform the flight crew 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. 

(b) 

ATC will inform the flight crew if it becomes necessary to turn off the aircraft’s ADS

−

B transmitter. 

Surveillance Systems 

4

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5

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