4/20/23 

AIM 

MHz transponders with integrated ADS

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B functionality extend the transponder message sets with additional 

ADS

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B information. This additional information is known as an “extended squitter” message and is referred to 

as 1090ES. ADS

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B equipment operating on 978 MHz is known as the Universal Access Transceiver (UAT). 

3. 

ADS

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B avionics can have the ability to both transmit and receive information. The transmission of 

ADS

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B information from an aircraft is known as ADS

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B Out. The receipt of ADS

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B information by an aircraft 

is known as ADS

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B In. All aircraft operating within the airspace defined in 14 CFR § 91.225 are required to 

transmit the information defined in § 91.227 using ADS

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B Out avionics. 

4. 

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. (Refer to 14 CFR §§ 

91.225 and 91.227.) While the regulations do not require it, operators equipped with ADS

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B In will realize 

additional benefits from ADS

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B broadcast services: Traffic Information Service – Broadcast (TIS

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B) 

(paragraph 4

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5

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8) and Flight Information Service 

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 Broadcast (FIS

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B) (paragraph 4

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5

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9). 

FIG 4

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5

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8 

ADS

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B, TIS

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B, and FIS

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B: 

Broadcast Services Architecture 

b.  ADS

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B Certification and Performance Requirements. 

ADS

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B equipment may be certified as a surveillance source for air traffic separation services using ADS

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B Out. 

ADS

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B equipment may also be certified for use with ADS

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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. 

c.  ADS

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B Capabilities and Procedures. 

1. 

ADS

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B enables improved surveillance services, both air

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to

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air and air

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to

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ground, especially in areas 

where radar is ineffective due to terrain or where it is impractical or cost prohibitive. Initial NAS applications 

Surveillance Systems 

4

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5

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