AIM 

4/20/23 

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System Management Downlink Message Elements (SYSD) 

CPDLC Message Sets 

Operational Definition in PANS

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ATM (Doc 4444) 

FANS 1/A 

ATN B1 

Response 

Message 

Element 

Identifier 

Message Element 

Intended Use 

Format for 

Message 

Element Display 

DM62 ERROR 

(error 

information) 

DM62 ERROR 

(error 

information) 

N 

SYSD

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1 

System

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generated 

notification of an 

error. 

SYSD

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1 

DM63 NOT 

CURRENT DATA 

AUTHORITY 

DM63 NOT 

CURRENT 

DATA 

AUTHORITY 

N 

SYSD

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3 

System

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generated 

rejection of any 

CPDLC message 

sent from a ground 

facility that is not 

the current data 

authority. 

SYSD

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3 

DM64 

(ICAO facility 

designation) 

Note 

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 Use by FANS 

1/A aircraft in B1 

environments. 

DM107 NOT 

AUTHORIZED 

NEXT DATA 

AUTHORITY 

Note 

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 CDA and 

NDA cannot be 

provided. 

N 

SYSD

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5 

System

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generated 

notification that the 

ground system is 

not designated as 

the next data 

authority (NDA), 

indicating the 

identity of the 

current data 

authority (CDA). 

Identity of the 

NDA, if any, is also 

reported. 

SYSD

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2. 

The following phraseology should be utilized by pilots for establishing contact with the designated 

facility: 

(a) 

When operating in a radar environment: On initial contact, the pilot should inform the controller of 

the aircraft’s assigned altitude preceded by the words “level,” or “climbing to,” or “descending to,” as 

appropriate; and the aircraft’s present vacating altitude, if applicable. 

EXAMPLE

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1. 

(Name) CENTER, (aircraft identification), LEVEL (altitude or flight level)

. 

2. 

(Name) CENTER, (aircraft identification), LEAVING (exact altitude or flight level), CLIMBING TO OR DESCENDING 

TO (altitude of flight level)

. 

NOTE

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Exact altitude or flight level means to the nearest 100 foot increment. Exact altitude or flight level reports on initial contact 

provide ATC with information required prior to using Mode C altitude information for separation purposes. 

(b) 

When operating in a nonradar environment: 

(1) 

On initial contact, the pilot should inform the controller of the aircraft’s present position, altitude 

and time estimate for the next reporting point. 

EXAMPLE

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(

Name) CENTER, (aircraft identification), (position), (altitude), ESTIMATING (reporting point) AT (time)

. 

(2) 

After initial contact, when a position report will be made, the pilot should give the controller a 

complete position report. 

EXAMPLE

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(

Name) CENTER, (aircraft identification), (position), (time), (altitude), (type of flight plan), (ETA and name of next 

reporting point), (the name of the next succeeding reporting point), AND (remarks)

. 

En Route Procedures

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