AIM

8/15/19

5

−

3

−

7

En Route Procedures

TBL 5

−

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 CON-
TACT 

(unit name)

(frequency)

W/U

COMU

−

1

Instruction to es-
tablish voice con-
tact with the speci-
fied ATS unit on
the specified fre-
quency.

CONTACT

(unit name)

 

(frequency)

UM120 MONITOR

(ICAO unit name)
(frequency)

UM120 MONI-
TOR (

unit name)

(frequency)

W/U

COMU

−

5

Instruction to mon-
itor the specified
ATS unit on the
specified frequen-
cy. The flight crew
is not required to
establish voice
contact on the fre-
quency.

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 re-
quired.

N/A

Y

COMD

−

1

Request for voice
contact on the spec-
ified frequency.

REQUEST
VOICE
CONTACT

(frequency)

TBL 5

−

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 Ele-

ment 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 im-
mediately comply
with the associated
instruction to avoid
imminent situation.

Immediately