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LDACS, aviation’s future terrestrial datalink, takes a big step forward

Successful first L-band Digital Aeronautical Communications System (LDACS) flight completed by DLR as part of the MICONAV project, marking the beginning of a new digital era in aviation communications.

On 26 March 2019, a Dassault Falcon 20 research aircraft, owned by DLR, the German Aerospace Centre, took off from Munich’s Oberpfaffenhofen airport equipped with a fully functional LDACS (L-band Digital Aeronautical Communications Systems) demonstrator. This flight marks the very first time that LDACS, aviation’s future terrestrial data link, has been tested in flight trials. LDACS flight testing will continue until early April to the south-west of Munich, where four LDACS ground stations have been installed, two of them with fully functional LDACS ground stations (transmit and receive), as well as two additional LDACS navigation stations (transmit only).

This LDACS flight testing campaign has been set up within MICONAV (Migration towards Integrated COM/NAV Avionics), a German national project. Besides DLR and the project leader Rohde & Schwarz, the MICONAV consortium comprises two SME partners, iAd GmbH and BPS GmbH. The work within MICONAV complements the SESAR European research framework and is directly relevant to the SESAR 2020 programme led by the SESAR Joint Undertaking of which EUROCONTROL is a founding member. Progress achieved by MICONAV is directly linked to SESAR 2020 project PJ14-02-01 (Future Communication Infrastructure Terrestrial Data Link), which concentrates the SESAR LDACS efforts.

The roots of the LDACS proposal lie in the EUROCONTROL FAA Action Plan 17 (AP17) activities (2004-2007). LDACS represents a key component of the aviation Future Communication Infrastructure (FCI), endorsed by ICAO in 2008, together with AeroMACS, the airport surface component and SATCOM. The FCI components were chosen to ensure efficient support for the aviation safety critical communications, enable additional capacity and meet the performance requirements of the advanced ATS functions and services required in the future concepts in the major regional ATM/CNS modernisation programmes, such as SESAR and NextGEN, while increasing spectrum efficiency and best utilising the available aviation spectrum bands.

LDACS is a modern telecommunication system, using state-of-the-art techniques used in commercial telecommunications. It is supporting secured communication exchanges, and can provide navigation as well as surveillance (ADS-C) functions, all of which make LDACS an integrated CNS technology.

As the name implies, LDACS is intended for operations in the L-Band (960-1164 MHz) and needs to coexist with other aviation systems in the band, such as the DME (Distance Measuring Equipment) navigation aids and SSR transponders. The demonstration of the compatibility of LDACS with the other users of the band is a critical task that needs to be completed, and EUROCONTROL will sponsor testing of LDACS with DME and TACAN equipment to complement previous testing campaigns. Furthermore, wave 2 of SESAR2020 is also expected to support a comprehensive testing campaign, covering other systems in the band including military, to demonstrate the LDACS spectrum compatibility and performance and support the validation of the LDACS standards currently in ICAO and EUROCAE in the future.

EUROCONTROL has been actively supporting European industry activities to define LDACS for many years now, contributing to the initial LDACS specifications in 2009 including recommendations for interference scenarios, compatibility criteria and test plans for various systems in the L-Band. EUROCONTROL continues to support LDACS activities, working in close cooperation with industry partners in the context of SESAR (SESAR1 and SESAR2020 wave 1). In SESAR, EUROCONTROL has been coordinating the LDACS standardisation activities and is overseeing international harmonisation, civil-military coordination and dissemination efforts.

The initial feedback for the first test flight on 26 March was very positive.

"The first flight test was very successful and illustrated the huge potential of LDACS as a future aviation data link for air traffic management. Key functionalities such as handover between ground stations and the LDACS ranging capability for A-PNT (Alternative Positioning, Navigation, and Timing) applications, as well as cyber-secured transmissions of CPDLC and ADS-C applications, have been demonstrated successfully”.

Dr.-Ing. Michael Schnell Group Leader at DLR

Flight testing will continue to evaluate more functionalities as well as key performance parameters such as data throughput, latency and other navigation parameters.