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 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) Message Element Intended Use Format for Message Element Display TBL 5-3-9 Voice Communications Downlink Message Elements (COMD) Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets FANS 1/A ATN B1 Response Message Element Identifier DM20 REQUEST VOICE CONTACT Note - Used when a frequency is not required. COMD-1 Message Element Intended Use Format for Message Element Display Request for voice REQUEST contact on the VOICE specified frequency. CONTACT (frequency) TBL 5-3-10 Emergency/Urgency Uplink Message Elements (EMGU) Operational Definition in PANS-ATM (Doc 4444) CPDLC Message Sets FANS 1/A ATN B1 Response Used in combination with LVLU-6 and LVLU-9, which is implemented in FANS 1/A as: UM38 IMMEDIATELY CLIMB TO (altitude) Message Element Identifier EMGU-2 Message Element Intended Use Instruction to immediately comply with the associated instruction to avoid imminent situation. Format for Message Element Display Immediately UM39 IMMEDIATELY DESCEND TO (altitude) En Route Procedures 5-3-7