Since 1st March 2013, Continuous Descent Approaches (CDA) and Continuous Climb Departures (CCD) are being tested for traffic to and out of Budapest Liszt Ferenc International Airport (Hungary), as part of the REACT-Plus project, with the main objective of reducing engine CO2 emissions.

The REACT-Plus (Reduction of Emissions using CDAs and CCDs in TMA) project is one of the nine projects of the third AIRE (Atlantic Interoperability Initiative to Reduce Emissions) cycle, spanning from 2012 to 2014. AIRE III builds on successes and insights gained through the previous waves of AIRE demonstration flights to make the implementation of greener ATM solutions and environmentally friendly procedures for all phases of flight with today’s technology a reality.

The project, a follow-up of AIRE II REACT-CR project expanding geographical coverage to Hungary, aims at optimization of terminal operations with the introduction of more efficient flight profiles in one of the busiest airports of Central Europe: Budapest. The objective is to accomplish more fuel-efficient climbs and descents through CDAs and CCDs in high density traffic.

The project, launched in June 2012 and co-financed by the SESAR JU, involves HungaroControl and low cost airline Wizz Air – both newcomers to AIRE – as well as an experienced industry partner, previously involved in REACT-CR, Pildo Labs. The three partners are working together to reduce environmental impact of air traffic operating in Budapest.

No special TMA procedures have been designed by HungaroControl to achieve the goals of REACT-Plus. Instead, the implementation of CDAs and CCDs is based on the operational introduction of a new ATM tool which is used since March this year by the ATCOs to optimize departures and arrivals. The new controller tool, called “MergeStrip”, provides simple and intuitive Distance-To-Go (DTG) information and separation alerts between arriving aircrafts to controllers.

The MergeStrip tool builds on and can be considered as an extension of the Point Merge concept developed by EUROCONTROL.

Point Merge

Point Merge aims to provide optimum profile with the minimum extra mileage flown. With Point Merge the aircraft in the initial approach phase flies on a P-RNAV arc and the approach controller creates spacing by using the static spacing tool (concentric arcs displayed on radar screen) to measure relative spacing and issues direct routing to the merge point in a timely manner. The Flight Management System thereby faces an unambiguous routing and optimal parameters of approach can be calculated. Fine tuning of relative spacing is done by speed control by comparing aircraft position to the arcs of the spacing tool. However, using this last method involves performing level flights while being at the concentric arcs.

The MergeStrip Tool proposed by HungaroControl is based on a method which can answer for both optimal profile and the sequencing limitations.

The MergeStrip tool was designed in order to make the comparison of the relative positions of aircrafts easier, almost as if all aircraft were flying in a continuous row on a straight line.

The essence of the MergeStrip concept is that, in an extended environment, a dynamic system can be used to create relative spacing instead of a static map element with fixed lateral flight path.

The advantage of this method is that controllers can thus check the relative spacing on the bottom time line bar any time (see figure) and, through a settings menu of the tool, modify the necessary spacing according to specific situations.

This allows Budapest Approach controllers to provide DTG information to pilots while giving themselves simple and intuitive information about the relative longitudinal spacing between arriving aircrafts. Pilots shall then be able to plan CDA operation starting theoretically at the top of descent.

MergeStrip components:

• Common route, for example final
• Merge points
• Relative Spacing Tool (here: plots on an imaginary centre line)
• High level concept of operation:
• delaying manoeuvre if necessary (speed control or vectoring)
• using FMS capabilities, optimised flying towards one of the merge points
• speed control for maintaining relative spacing

As the “MergeStrip” tool is already deployed at Budapest Air Traffic Control Center, accurate real-time DTG information can be provided to all arriving flights, enabling pilots to use Flight Management System (FMS) capabilities to plan a predictable continuous descent approach. For this reason, during the daily routine environment none of the flights preparing for arrival are excluded and all airlines benefit from the enhanced operations; a mandatory step in order to reach final implementation of CDAs.

REACT-Plus will demonstrate the benefits of using the MergeStrip tool, both from the Safety and Environmental point of view. Data for a total of 200 CDA flights and 200 non-CDA flights will be collected as part of the project. Implementation of expected to result in environment benefits with a reduction of fuel burn between 50-70kg per arriving flight.

MergeStrip tool screenshot