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AIM

4/20/23

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3

7

En Route Procedures

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3

8

Voice Communications Uplink Message Elements (COMU)

CPDLC Message Sets

Operational Definition in PANS

ATM (Doc 4444)

FANS 1/A

ATN B1

Response

Message
Element

Identifier

Message Element

Intended Use

Format for

Message Element

Display

UM117 CONTACT

(ICAO unit name)
(frequency)

UM117
CONTACT 

(unit

name)

 

(frequency)

W/U

COMU

1

Instruction to
establish voice
contact with the
specified ATS unit
on the specified
frequency.

CONTACT 

(unit

name)

 

(frequency)

UM120 MONITOR

(ICAO unit name)
(frequency)

UM120
MONITOR (

unit

name)

 

(frequency)

W/U

COMU

5

Instruction to
monitor the
specified ATS unit
on the specified
frequency. The
flight crew is not
required to
establish voice
contact on the
frequency.

MONITOR 

(unit

name)

 

(frequency)

TBL 5

3

9

Voice Communications Downlink Message Elements (COMD)

CPDLC Message Sets

Operational Definition in PANS

ATM (Doc 4444)

FANS 1/A

ATN B1

Response

Message
Element

Identifier

Message Element

Intended Use

Format for

Message Element

Display

DM20 REQUEST
VOICE CONTACT

Note  

 Used when a

frequency is not
required.

N/A

Y

COMD

1

Request for voice
contact on the
specified frequency.

REQUEST
VOICE
CONTACT

(frequency)

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3

10

Emergency/Urgency Uplink Message Elements (EMGU)

CPDLC Message Sets

Operational Definition in PANS

ATM (Doc 4444)

FANS 1/A

ATN B1

Response

Message
Element

Identifier

Message Element

Intended Use

Format for

Message
Element

Display

Used in combination with
LVLU

6 and LVLU

9,

which is implemented in 
FANS 1/A as:

UM38 IMMEDIATELY
CLIMB TO (

altitude

)

UM39 IMMEDIATELY
DESCEND TO (

altitude

)

N/A

N

EMGU

2

Instruction to
immediately
comply with the
associated
instruction to avoid
imminent situation.

Immediately