Airbus MCDU ATSU & ATC: Datalink (CPDLC) Operations Explained
With the FMGC fully covered, the last piece of the MCDU is the ATSU (Air Traffic Services Unit) — the aircraft's datalink to controllers. This guide explains how to log on, send CPDLC text requests to ATC, and file position reports, all from the MCDU.
1. What ATSU is & two ways to open ATC
The ATSU (Air Traffic Services Unit) manages the aircraft's digital communications with air traffic control and airline operations. There are two ways to reach the ATC page from the MCDU:
- From the
MCDU MENU, press2L(ATSU), thenL1for the ATC page. - Or simply press the
ATC COMMkey on the keypad to jump there directly.
2. FANS & datalink (CPDLC) basics
FANS (Future Air Navigation System) supplements voice radio with text messages — the core of what's known as CPDLC (Controller–Pilot Data Link Communications). There are three variants:
Oceanic operations, originally on the A330 / A340.
Updated version, fitted to all Airbus aircraft since 2004.
Continental flights — not compatible with FANS A.
3. Logging on: notification & connection status
Before you can exchange messages, you have to log on to the controlling station:
- Press
R6(NOTIFICATION). - Enter the station identifier — for example
ZUUU. - Press
R2(NOTIFY) to send the logon request. - Check
R4(CONNECTION STATUS) to confirm the link is active.
The ADS status shows whether automatic position surveillance is transmitting your position to ATC.
4. Making requests: LAT, VERT & OTHER
Once connected, you send requests to ATC in three groups.
LAT REQ — lateral requests
Request direct routing to a waypoint.
Request a deviation for weather.
Request a standard arrival.
Request a parallel offset from the route.
Request a specific heading or ground track.
"When can we expect back on route?"
VERT REQ — vertical requests
Request a climb or descent to an altitude.
Request a specific altitude or speed.
Request a block of altitudes.
Request a cruise climb.
Request a speed range.
Ask when an altitude or speed change can be expected.
OTHER REQ
Covers voice-contact frequency entry, OWN SEPARATION & VMC (for VFR), and CLEARANCE requests.
5. Reports, MSG LOG & ACMS
Reports
Automatic reports appear under ATC REPORTS. A Manual Position Report (MPR) asks for your present position (PPOS, written as integer latitude + longitude, e.g. N30E104), UTC time, altitude, and the next waypoint with its ETA. Further report types cover winds, icing (on a T/L/M/S scale), SAT, turbulence, fuel, airspeed and groundspeed.
MSG LOG
The MSG LOG stores every ATC message you've sent, so you can review any of them individually.
ACMS
The ACMS (Aircraft Condition Monitoring System) records data across all phases of flight. It's view-only — useful for monitoring, not something you edit.
And that completes the Airbus MCDU series — from a cold-and-dark FMGC all the way through datalink communications with ATC. You now have the full workflow to program and fly the aircraft from the MCDU.
You've learned the MCDU. Now feel it.
Everything in this series runs on a backlit Rowsfire panel — tactile keys, authentic Airbus layout, plug-and-play with MSFS & X-Plane.
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