IEEE - Aerospace and Electronic Systems - April 2021 - 36

Feature Article:

DOI. No. 10.1109/MAES.2021.3050678

Beneﬁts for Greek Regional Airports Through
Innovative Approach Technology Using an LPV to GLS
Converter: A Case Study for Corfu and Thessaloniki
Thomas Dautermann, Thomas Ludwig, and Robert Geister, German Aerospace
Center, Institute of Flight Guidance, Braunschweig 38108, Germany
Eleni Akkogiounoglou, Fraport Greece, Athens 15123, Greece; and also
Thorsten Astheimer Fraport AG Germany, Frankfurt 60547, Germany

INTRODUCTION
During the recent past, aviation navigation has slowly
changed from having a ground-based infrastructure to utilization of global navigation satellite systems (GNSS). Navigation using satellite signals is based on signal propagation
time measurements from the satellite to the receiver,
knowledge of the satellite position, and subsequent triangulation [1]. The International Civil Aviation Organization
(ICAO) harmonized the need for comparable standards in
satellite navigation within the performance-based navigation (PBN) concept [8]. Here, navigation system performance requirements are specified for on-board navigation
capability with a high level of accuracy and integrity.
For the approach to airports, ICAO is differentiating
between nonprecision approaches (without vertical guidance)
and precision approaches (with vertical guidance). Precision
approaches with three-dimensional guidance to a dedicated
runway can either be achieved by traditional ground-based
landing aids (i.e., ILS, MLS) or by GNSS-based approaches.
However, due to atmospheric interference and noise in the
horizontal direction, a position resolution is only possible
with an accuracy (95%) of several meters, depending on

Authors' current address: Thomas Dautermann, Thomas
Ludwig, and Robert Geister, German Aerospace Center,
Institute of Flight Guidance, 38108 Braunschweig,
Germany (e-mail thomas.dautermann@dlr.de). Eleni
Akkogiounoglou, Fraport Greece, 15123 Marousi,
Athens, Greece; and also Thorsten Astheimer Fraport
AG Germany, 60547 Frankfurt, Germany.
Manuscript received August 26, 2020; accepted
December 16, 2020, and ready for publication January
7, 2021.
Review handled by Peter Willett.
0885-8985/21/$26.00 ß 2021 IEEE
36

satellite geometry, and in the vertical direction it is even
more diluted due to the absence of signals originating below
the receiver. For this reason, the GNSS signals need to be
augmented to be used for precision approaches to airports.
Generally, two different augmentation systems exist to
improve the lateral and especially the vertical navigation
integrity, accuracy, continuity, and availability. These are
based on ground stations at fixed and surveyed locations.
For the ground-based augmentation system (GBAS; [12]),
these reference sites are located at the respective airport.
Correction and integrity data are provided via a VHF aeronautical data link. For the second system, the satellite based
augmentation system (SBAS) [11], [13], reference sites are
distributed over a country to continental sized service region
and the data are provided via satellite downlink. Both systems use final approach segment (FAS) data blocks to
describe the approach funnel used by aircraft to approach
the runway. This data block contains all the necessary information for the avionics to compute virtual localizer and
glide path information. Using GBAS, the system is called
the GNSS landing system (GLS) and the FAS data block is
provided at the airport by the VHF data broadcast. Using
SBAS, the procedure is called localizer performance with
vertical guidance (LPV). The LPV procedure is typically
available as lowest minimum on an RNP approach procedure [5], and the FAS data block is provided by the navigation database of the flight management system. Correction
information and FAS data are largely identical for both systems (GLS and SBAS). Both systems enable a decision
height as low as 200-ft above the aerodrome and a minimum
Runway Visual Range (RVR) of 550 m.
At present, automated landings can only be carried out
with precision guidance systems such as the instrument
landing system (ILS) [7], microwave landing system
(MLS), or the GLS [10]. The common feature of all these
systems is the routing of guidance signals directly from the

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