urope is looking to employ datalink communications to ease air traffic delay and capacity woes

Emma Kelly/LONDON

Europe is on the verge of implementing one of the most important communication programmes the continent has ever embarked on.

The Link 2000+ programme is intended to lead to the deployment of operational mobile datalink services for air traffic control (ATC) and airline operational communications (AOC) in a large part of Europe from 2007 and is seen as the continent's trump card in coping with ever-growing air traffic.

The programme has already received seals of approval from influential industry groups. Airlines, air traffic service (ATS) and communications providers and airframe manufacturers have registered their support for the plan as the continent attempts to sort out its delay and capacity problems. Eurocontrol now intends to write to key ATS providers and airlines to get firm commitments.

The Link 2000+ master plan - formulated with extensive involvement from airlines, ATS providers, industry associations, the Joint Aviation Authorities, airframe manufacturers and communication providers - has already passed significant hurdles. It was endorsed by Eurocontrol's air traffic management (ATM)/communication, navigation and surveillance consultancy group last September, while the Chief Executive Standing Conference, which comprises the heads of Europe's air navigation service providers, gave a green light to the plan in early November.

Positive response

To gauge support for the plan and ensure stakeholders were on board at an early stage, Eurocontrol wrote to decision makers at airlines, and to ATS and communication providers last year and received a "positive response", says Alex Wandels, Eurocontrol's Link 2000+ programme manager. The co-operation, commitment and co-ordination of all of these stakeholders is vital if the programme is to succeed, concedes Eurocontrol. "The interest is growing," says Wandels.

Europe's Link 2000+ master plan calls for the implementation of operational air/ground datalink services for ATC based on the aeronautical telecommunication network (ATN) over VHF Data Link Mode 2 (VDL-2). Implementation is planned between 2002 and 2007 in 11 European states: Austria, Belgium, France, Germany, Ireland, Italy, the Netherlands, Slovenia, Spain, Switzerland and the UK. This area was selected because it comprises a number of area control centres (ACC) and airports where datalink is expected to provide the highest capacity and safety benefits. In addition, these countries have ATC systems that are technically capable of supporting air/ground datalink in the target time scale. Initial implementation at airports is planned in 2003, followed by ACCs coming on line in 2005 and services becoming available throughout the region by 2007.

By the end of next year detailed planning of the programme is due to be completed, while policy decisions concerning regulation, certification and institutional arrangements must also be made by then. Detailed planning is already under way among stakeholders, says Wandels. Between 2003 and 2005, ATM system, communication and airborne equipment development, testing, installation and integration activities are planned. This period will include pre-operational trials and implementation of datalink services at selected airports.

The European air navigation organisation's blueprint for ATM development - ATM Strategy for 2000+ - identifies datalink as a key enabler for the decade. Europe is pinning its hopes on the technology in the belief that it will contribute to the extra capacity that will be required. It also satisfies the industry need for ATS automation and the need for a global communication standard for ATS.

The technology promises much. It is expected to reduce communications workload for air traffic controllers and pilots, increase communication reliability and allow the exchange of information between airborne and ground-based systems. In turn, the reduced communications workload is expected to facilitate increased airspace capacity and reduced delays, both of which are vital for Europe.

The principal limitation on ATM capacity is controller workload, of which a substantial part is due to handling radio/telephony (R/T). The limit to sector capacity today is often the controller's R/T workload, according to Eurocontrol. Traditional methods of containing this workload problem by increasing sectors and number of controllers are no longer proving effective in certain areas of Europe. To increase capacity beyond this point requires operational improvements that can increase ATC productivity, with controller-pilot datalink communications (CPDLC) for routine communications between controller and pilot seen as the most promising tool to achieve this. Air/ground datalink can reduce the controller's and pilot's workload through a decrease in R/T traffic. In turn, this benefit can be exploited by increasing the airspace covered by one sector. Eurocontrol stresses, however, that "this is a long process, which starts by building up the controller's and the pilot's confidence in the new communication medium and which can gradually lead to increased sector capacity".

Datalink is also expected to contribute to higher safety levels through the availability of a second communication channel, fewer errors and reduced pilot and controller fatigue. Radio communications have a number of drawbacks in a busy air traffic environment, Eurocontrol points out. Pilots have to listen to every controller-initiated communication, even though only one in 20 of these is addressed to the flight in question. In addition, a limited understanding of the English language and regional accents frequently cause misunderstandings. An electronic or hard copy of the message in the cockpit is expected to reduce errors.

Key tool

Datalink is also seen as the key tool for the automation of ATC services and as a stepping stone to more advanced applications.

Without datalink communications, the delay situation in Europe will worsen - increasing by 25% a year until 2005 and 10% each year from 2005 to 2010 - according to the business case for Link 2000+, which was conducted by the Boeing-led airline grouping, the CNS/ ATM Focus Team (C/AFT), and developed with airlines, airline associations, ATS providers, aircraft manufacturers, aeronautical communication providers, Eurocontrol and the US Federal Aviation Administration.

From 2000-2020, the business case shows a benefit to cost ratio of 4:1. The investment is concentrated largely in the first seven years, with benefits mainly generated by AOC applications, and greatest after 2007 when ATC applications start to contribute, says the study.

Upgrading an Airborne Communications Addressing and Reporting System (ACARS)-equipped aircraft to VDL-2 is expected to cost around €150,000 ($138,000) as a retrofit and €90,000 as a forward-fit, while the Link 2000+ services update cost is estimated to be €100,000 per VDL-2-equipped aircraft. Upgrading all ACCs and airports in the Link 2000+ region will cost €298 million, with an ACC upgrade estimated at between €5million and €30 million, depending on the complexity of the system, and an airport ATS upgrade estimated at less than c1 million. In return, the workload reduction could reach 29%, capacity gains could be as much as 14% and air traffic flow management (ATFM) delay reductions could reach 53%.

Datalink demonstrations

Operational datalink communications have already been demonstrated in projects and trials designed to prove the concepts and applications. Both the Preliminary Eurocontrol Test of Air/Ground Data Link (PETAL II) and European Pre-Operational Data Link Applications (EOLIA) projects have validated the operational use of air/ground datalink to support controller-pilot communications. The supporting services and infrastructure have also been proven, with EOLIA demonstrating the feasibility of modifying ATC data processing and airborne systems to accommodate end-to-end communications. The Prototype ATN (PROATN) and ATN Trials Infrastructure (ATIF) projects also demonstrated the feasibility of an ATN internet meeting the requirements of air/ground communications.

It is the PETAL II trial that is really paving the way for the implementation of Link 2000+. Launched in April 1998, PETAL II is a three-phase programme conducted in an operational ATC environment, with controllers at Eurocontrol's Maastricht centre communicating with aircraft crew by digital datalink, with voice communications back-up. The project has been using three different datalink technologies - the North European ADS-B Network (NEAN) VHF Data Link Mode 4 infrastructure, the satellite communication-based future air navigation system (FANS-1/A), and the ATN. PETAL II has involved numerous airlines, including Scandinavian Airlines (SAS), Lufthansa, Air Canada, American Airlines, Air New Zealand and United Airlines. The first flight of an ATN-equipped aircraft was conducted late last year, when DERA's BAC One-Eleven test aircraft and a Dutch National Aerospace Laboratory's Cessna Citation sent datalink messages over the ATN in-flight (Flight International, 7-13 November 2000). The first operational ATN flights are due to be conducted by American Airlines Boeing 767-300ERs fitted with Rockwell Collins avionics from May, followed by Honeywell-equipped 747-400s and Airbus A320s operated by Northwest Airlines and Swissair, respectively.

Simulations to support the Link 2000+ case have also been conducted at the Eurocontrol Experimental Centre, to determine the effect of CPDLC operations on controller workload, on the level of service provided and on controllers' perception of safety.

In the simulations, the controllers found datalink operations easy to understand and work with, and although they were unsure as to whether it enables the provision of a better service, the general view was that CPDLC could allow more aircraft to be handled. The communication workload reduced by 45%, 61% and 84% when the aircraft fleet was 50%, 75% and 100% datalink-equipped, respectively.

The major challenge facing Link 2000+ is whether all players meet their part of the bargain, with the biggest risk being a lack of equipped ACCs and aircraft, concedes Eurocontrol. A realistic objective for fleet equipage is 25% by 2007, Wandels believes. Operational and financial incentives are expected to be offered to airlines that equip early, with a group currently studying this issue.

To mitigate the risk, Eurocontrol intends to start formalising the industry support. Wandels says: "We will start a letter of commitment procedure in which partners will formally commit to equip identified centres or numbers of aircraft by a certain date."

CAPACITY GAIN BASED ON RATE OF EQUIPAGE

% Rate of datalink equipage

Workload reduction

Capacity gain

0%

0%

0%

50%

16%

8%

75%

22%

11%

100%

29%

14%

Source: C/AFT European datalink investment analysis

AFTM DELAY REDUCTION BASED ON FLEET EQUIPAGE

% Rate of equipage

Capacity increase

AFTM delay reduction

25%

3.4%

10%

50%

8%

31%

75%

11%

44%

100%

14%

53%

Based on traffic sample from April 1999 Source: C/AFT European datalink investment analysis

Source: Flight International