Pilots are getting the message as Europe forges ahead on datalink communications, with crews logging on in their thousands to Eurocontrol’s new technology
While the US Federal Aviation Administration looks to the future, but remains bogged down in the present, its European counterparts are moving steadily ahead in implementing technologies crucial to future air traffic management. This is most evident in the deployment of controller-pilot datalink communications (CPDLC).
Forced by budget cuts to shelve its datalink programme last year, the FAA has watched as Eurocontrol has steadily advanced the operational use of CPDLC at its Maastricht upper area control centre in the Netherlands. The Europeans are now focusing attention on taking datalink services to the next level.
Maastricht centre formally introduced CPDLC in June 2003 and over the first three months of this year nearly 3,900 flights performed a datalink log-on with the facility. Eurocontrol cites this high degree of initial log-on as evidence that cockpit crews support CPDLC, and says that nearly 90% of these flights subsequently carried out a datalink message exchange with Maastricht controllers. Around 10,000 messages were transmitted in total.
Faster responses
CPDLC round-trip response times, which are critical to maintaining smooth traffic flow, have fallen to around 28s. Aircraft are typically exchanging around three CPDLC messages with the centre, but this can increase to a dozen for some flights.
Several routine instructions – such as frequency contact instructions and secondary surveillance radar code changes – can be sent by controllers and these have been joined by messages about heading, turn and flight-level information. Human-machine interface adaptation also means that controllers are able to uplink certain CPDLC messages on their air traffic situation displays rather than through a separate screen.
But earlier this year Maastricht took its CPDLC capability further by handing limited decision-making to the ground system. Modernisation of the system means it can uplink secondary radar code-change commands automatically. Code changes are required for aircraft entering the Maastricht airspace from the north, but were previously conducted via voice instructions.
Flight record
Maastricht centre handled a record number of flights on 1 July: almost 4,500 in a single day. Given that up to 400 aircraft each day require the code-change instruction, switching the uplink task to automated CPDLC is expected to reduce workload and save controllers 40min.
Automatic uplink requires a number of conditions to be fulfilled; air traffic controllers are able to override the system at any time and the instruction appears no different to pilots from the equivalent manual CPDLC uplink.
“This is really only the first step,” says Maastricht centre datalink operations manager Paul Conroy. “We wanted to prove we were technically able to do it as well as test the controllers’ acceptance.” He says the acceptance has been “very good” and that automated CPDLC could potentially be extended to uplinking frequency instructions, constraint information and other data.
Under the Eurocontrol Link 2000+ programme, several European centres are preparing to introduce their own CPDLC services. Core-area en-route centres at Reims in France, Karlsruhe in Germany, Lisbon and Rome are among a handful that intends to follow Maastricht in implementing datalink by 2007.
But Eurocontrol is looking beyond Link 2000+ to post-2007 CPDLC applications under a collective surveillance and communications datalink programme known as Cascade. The organisation aims to build upon Link 2000+ and Mode-S radar to validate a range of CPDLC and automatic dependent surveillance – broadcast (ADS-B) services in two development streams, for implementation in the 2008-11 timeframe.
Automatic CPDLC is one of the earlier “Stream 1” services being validated. Belgian carrier SN Brussels Airlines is to participate next year in another Cascade Stream 1 project, called D-TAXI, which will involve providing pushback and taxi clearances over datalink rather than voice at Brussels National airport.
SN Brussels Airlines will equip its Airbus A319 and A330 fleet with avionics allowing pilots to accept and respond to the clearances. “We believe it is an important project that will bring both safety and efficiency gains for our operations,” says the carrier’s vice-president for flight operations, Dirk Vrebos.
Eurocontrol adds that the D-TAXI trial, which will also involve air navigation service Belgocontrol, communication provider Sita and the Dutch NLR research centre, will enhance safety by cutting the risk of misunderstandings.
Cascade Stream 1 applications will include the ability for pilots to downlink flight-plan modifications and preferences – as well as emergency information – to controllers. Pilots will also be able to receive operational and meteorological information pertaining to approach and departure.
Validation results
Eurocontrol Cascade programme manager Jose Roca says that crucial validation results from the various applications will begin emerging towards the end of this year. “All of these validations will support the business case for Cascade,” he says. “At the moment they’re looking positive, providing operational benefits where we’ve expected them.”
Eurocontrol’s Experimental Centre at Bretigny in France has just completed a month-long series of real-time Stream 1 simulations – involving 16 controllers from Maastricht, Ireland, Italy, Portugal, Romania and Spain – with the aim of familiarising them with Stream 1 services. The simulations focused on pilot-preference downlink, automatic CPDLC and derivation of aircraft data via ADS-B for ground applications. Roca says that the results of these validation exercises should be known in September.
Within the surveillance domain, Cascade aims to validate use of ADS-B to enhance radar coverage or provide surveillance in non-radar areas. Assessment of ADS-B’s potential within the south-east UK and Scotland is the subject of a newly released study undertaken by air navigation provider National Air Traffic Services and Helios Technology.
The study has concluded that ADS-B ground stations could provide coverage for the whole of south-east UK terminal airspace above flight-level 55 and that ADS-B’s increased accuracy could offset increased traffic levels and result in a lower collision risk than the comparable radar-only scenario. In Scotland, it adds, ADS-B would be able to match radar performance.
Future Cascade applications, grouped as “Stream 2”, will move towards enhancing cockpit crews’ traffic situational awareness, both on the ground and in the air, and enable controllers and pilots to adjust their traditional roles to carry out separation, sequencing and merging tasks.
More effective sequencing has been highlighted by a Eurocontrol performance review commission study as a key technique to improving punctuality at European airports. Such work is already under way. Eurocontrol has recently released the results of sequencing and merging simulations within Frankfurt airspace carried out in co-operation with German air navigation service DFS. These simulations were designed to validate operational airborne separation assistance procedures, such as merge-behind and remain-behind, which aim to improve the efficiency of traffic streams by transferring spacing tasks from the controller to the flightcrew.
The simulation demonstrated that controllers found the Frankfurt airspace particularly complex and that early sequencing and merging procedures should probably be undertaken in airspace regions with segregated traffic streams and long sectors. Frankfurt is to undergo an airspace reconfiguration around the end of this year, however, and further simulations are planned – potentially including greater use of datalink rather than voice communications – in order to assess whether the new procedures illustrate greater benefits in the redesigned airspace. -
Cascade Stream 2 services, which will be introduced from around 2010, will also include downstream clearances – enabling pilots to communicate requests in advance to air traffic centres that have yet to take responsibility for the flight – as well as applications to check flight-plan consistency, and to allow controllers and pilots to renegotiate trajectories to improve air traffic management efficiency.
DAVID KAMINSKI-MORROW/LONDON
Source: Flight International
