CPDLC In Europe: Handy New Guidance from Eurocontrol

Eurocontrol has put out a new two-page CPDLC cheat sheet for European operations. It’s short, non-technical and really useful – especially if you don’t use CPDLC everyday.

Click for PDF.

The interesting part isn’t the basics though. Most crew already know that CPDLC is mandatory in much of Europe. What’s more juicy is the human factors stuff – the small misunderstandings and bad habits that are still creating problems out there.

This guidance serves as a reminder of some persistent errors. Here is a brief summary of those.

CLEARED TO vs. PROCEED DIRECT TO

Make sure you follow the clearance correctly.

EUROCONTROL points out that a CPDLC uplink saying “CLEARED TO [WAYPOINT D] VIA [A B C] is a route clearance, not a direct-to shortcut.

Those are issued by the phrase “PROCEED DIRECT TO.” Apparently enough of us are still getting this wrong to be specifically mentioned in the bulletin.

Assigned speeds don’t just disappear

The guide warns crew not to assume a CPDLC speed restriction quietly disappears just because the aircraft later gets another route or level clearance. It’s no different to a voice clearance, an assigned speed sticks unless you are told otherwise.

Why would this be happening? A few suggestions.

It’s possible that pilots load the route amendment but miss the associated speed. Mixed voice and CPDLC environments can also create ambiguity about which clearance is ‘current’ – more on that in moment.

Then there’s workload – especially in dense European airspace. When we get busy, it can be easy to overlook an old datalink clearance sitting in the message stack.

Don’t deliberately log-off

This is a biggie.

EUROCONTROL reminds us that a CPDLC clearance holds the same value as a voice clearance. Deliberately disconnecting or turning off CPDLC is akin to turning off your radios. Just don’t do it. Why would crew be doing this? We don’t know – but reverting yourself to voice is no-bueno.

Why do we still get voice clearances, even when fully logged on?

Some clearances are too urgent – voice is just quicker, especially in the case of level changes. Switching to voice rather than waiting for a CPDLC message to be sent and received can avoid an unnecessary level-off.

Then there’s network performance – no technology is perfect 100% all of the time, and things can slow down.

And simple practicality for the controller. It may just be easier to hop on voice.

Failed Log Ons

We’ve all been there – a logon simply refuses to work without explanation. It’s extremely frustrating!

In many cases the problem comes down to small setup errors – the wrong logon code, an outdated flight plan after an aircraft swap, or trying to connect to a sector that’s not included in your filed route.

Even something as simple as the wrong callsign format or VHF3 not being set to DATA can stop the connection. The fall back is to immediately revert to voice, but this adds workload for all concerned.

It’s not complicated, just human

There’s nothing terribly difficult or technical in Eurocontrol’s new guidance, but it does highlight how CPDLC introduces its own traps – especially in busy, unfamiliar airspace where crews may switch between voice and CPDLC several times in just one flight.

The guide is a useful reminder that getting the basics right with CPDLC is just as important as good radio discipline.

One extra point (especially for US operators)

Europe is a little bit different when it comes to CPDLC. Most of the network uses the ATN system over VHF datalink, not the FANS over SATCOM/HF set up you may be more familiar with in oceanic airspace. The practical takeaway is that if VHF 3 fails, or that radio is MEL’d, you’ll generally lose European CPDLC capability for the whole flight – even if SATCOM datalink still works fine everywhere else.

Another thing that catches crew out is the transition from oceanic to European airspace. If you come off the NAT already logged on to an oceanic FANS datalink service provider, you will often need to manually log off and then back on the European ATN network. Most avionics do not automatically switch between FANS and ATN. If a crew forgets to re-logon, you can end up entering CPDLC airspace with no active connection, even if all looks okay on board.

Bottom line – make sure you actively verify the aircraft has successfully established ATN logon before entering European airspace.

CPDLC In Europe: Handy New Guidance from Eurocontrol