The idea of sending instructions to an aircraft as data rather than voice communication seems like an obviously good one. It would lessen the chances of a misunderstanding while at the same time freeing up the pilot and controller for other tasks – a two-fold safety advantage.

Yet it may be a surprise to many people that a lot of communication between air traffic control and aircraft is still via two people at either end of a radio, but that’s expected to change in the coming years with the greater use of datalink technology.

The journey to this point has been a long one. Datalink was first used within NATS back in 1999/2000 to enable us to better communicate with traffic over the North Atlantic where there is little or no radar coverage and VHF radio contact is impossible. As a result, around 70% of transatlantic traffic is now datalink enabled. That means we no longer have to respond to communication difficulties by increasing separation distances, something that results in delays and a loss of capacity.

However, oceanic traffic accounts for only 1,200 of the 6,000 or so flights through UK airspace every day. As such, in August this year we completed the roll out of datalink technologies at our two en-route centres at Swanwick and Prestwick, meaning we are now ready to provide air traffic services via datalink to any equipped aircraft anywhere in our airspace.


This has taken a significant investment – including large scale upgrades to existing legacy systems; the training of every en-route controller in the UK; and changes to our central flight data processing system. Installing VHF stations across the UK in some very remote locations was a major engineering challenge and as part of our customer engagement, we also ran three airline workshops, with representation from BA, Virgin, SAS, Thomson, FlyBe, Easyjet and, Monarch amongst others.

To date, equipage levels in domestic airspace are still low – in the tens of aircraft a day – but we’re already starting to see the benefits. There was an example of three aircraft all with call signs ending ‘71’ where the controller elected to use datalink to communicate with one of them to eliminate the potential for any confusion between the pilots.

And while numbers are modest today, aircraft equipage will grow as airlines move to meet a European deadline and as more ground based infrastructure becomes available. Eurocontrol is predicting a 75% equipage rate by the end of 2015, with datalink forming an important technical aspect of achieving the vision of a Single European Sky.

The greater the take-up the greater the benefits for all parties will be.

At NATS, we are trying to reduce our controllers’ workloads and increase their wider understanding of the air traffic environment in the safest way possible. The aim is to cut down on routine tasks to enable them to devote more time to improving the efficiency of the services offered to our customers.

Datalink will definitely play an important role in achieving that aim in the coming years.


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Jay (O'HareAviation)

How well does this idea work in emergencies?



Mike Lee

Hi David,

With the increased number of drones appearing, how will this affect datalink technology in the future?




Rana Eymur

Hi David…I am sure you are aware that EFPS at most NATS airports have used Datalink (DCL) for pushback clearance for a number of years now. At Heathrow almost 65% of aircraft now use this on a daily basis and we have updated the service recently to make it fully automated to further reduce controller workload.

Best Regards

Rana Eymur NSL HH



Peter Hargreaves

Interesting. I just wonder about (a) emergency situations and (b) situational awareness for pilots. Any thoughts?

Thank you Jay, Mike, Rana and Peter for taking the time to comment – you raised some good questions about emergencies, drones and situational awareness.

In my opinion, having a datalink capability should only help emergency situations, however I would expect the main method of communication between pilot and controller in these situations to continue to be be via voice for quite a while yet.

Regarding drones, or Unmanned Aerial Vehicles, there is a lot of work going on to ensure they can operate safely with other air traffic – I am sure datalink will have an important role in this. My colleague Brendan Kelly wrote about this a few weeks ago in relation to Amazon’s delivery drones –

Finally, situational awareness of pilots, which they achieve, in part, by listening to the communications between controllers and all other aircraft in their area – I agree it is vitally important that they are able to maintain this awareness as technology changes.

I don’t believe this has been adversely affected by current technology, but it will be an issue that needs to be considered as this (and any other) new technology is deployed. This is something that our industry is generally very good at and there are established forums where the Air Navigation Service Providers, aircraft & equipment manufacturers, airlines and regulators can all work through the issues together.



Graham Lake

Did you know that in May 2014 it will be 25 years since NATS sent its first data link oceanic clearance!? Sent using the SITA VHF Aircom system to an Air Canada B767-200 westbound from London. Air Canada and BA asked NATS to introduced the datalink capability to support two pilot, twin engined Atlantic ops! Gander Center was already offering eastbound clearances by datalink even then.



Kieran O'Carroll

Glad to see NATS facilitating both FANS and ATN based data link. The continental European implementation of ATN based data link has been a debacle from the airspace user perspective resulting in some major airlines terminating their use of data link on safety grounds. The EU Commission mandate on airspace users to equip whilst some States and ANSPs failed to comply has markedly damaged confidence in the European implementation.The ATN Provider Abort issue hasn’t helped either. Airlines look forward to the promised benefits. In the meantime they struggle with the excessive costs of equipping their airframes.



Brian 72

Datalink or CPDLC which was introduced last year in the enroute environment hasn’t worked very well at all. That is the very polite version.
It’s also wasted a lot of money



David Walker

VHF Datalink (ACARS etc) carried oceanic clearances from Gander to my 767 fleet years before anyone else. Before my retirement we had received Oceanic ATC communications from YQX. PIK Iceland and Santa Maria
Mind you some of those ATC systems didn’t’know we had intercepted their attempts to deliver that info by a voice channel
Capt David Walker. Flight Manager B767 Air Canada Retired. 1991


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