The Twente demonstrations saw NLR’s research Cessna Citation II join a Lufthansa A319 and a TUI fly B737 Max 8 to evaluate under real visual conditions, using the Indra Navia GBAS ground station, the runway dual markings and dual precision approach path indicator (PAPI) needed for Second Runway Aiming Point (SRAP) and IGS (Increased Glide Slope)-to-SRAP approaches.
The trials, which will be evaluating visual aspects, flyability and gathering performance data, are part of the SESAR Very Large Demonstration (VLD1) DREAMS project, which aims to evaluate whether a series of new Enhanced Arrival Procedures (EAP) will bring benefits in terms of noise and optimisation of wake separation, as well as reduced flight time or runway occupancy time for certain runway configurations. The project gathers nine partners under coordination by Indra: two ANSPs (DFS, ENAV), two aircraft manufacturers (Airbus, Dassault), one aircraft system manufacturer (HONEYWELL), two research organisations (NLR, DLR), and EUROCONTROL. In addition, airspace users (Lufthansa, TUI Fly) are also participating under contractual arrangements.
Overall, DREAMS aims to increase operational efficiency, shorten flying times and lower emissions by bringing EAP supported by advanced GNSS navigation technologies closer to industrialisation.
The trials are testing the following EAP:
- Dual final approach slope, one being steeper, namely ISGS (Increased Second Glide Slope);
- Dual thresholds to single runway, namely SRAP (Second Runway Aiming Point);
- A combination of the two: IGS-to-SRAP (Increased Glide Slope to Second Runway Aiming Point);
- Operation of GBAS GAST C in CAT II conditions.
EUROCONTROL has a multiple role, leading the work programme on SRAP & IGS-to-SRAP demonstration at Twente, specifically contributing to the demo on GBAS GAST-D performance analysis using our own latest generation Multi Mode Receiver (MMR); leading the DEMO Plan deliverable; and leading the task on standardisation and regulatory framework evolution.
The SESAR VLD1 DREAMS project is a continuation of the work undertaken under two other SESAR projects related to airport capacity (PJ.02) and integrated CNS (PJ.14), both with strong involvement of EUROCONTROL.
Twente SRAP & IGS-to-SRAP (October ‘21), with NLR test aircraft with full GAST D capability using the Indra Navia ground station, TUI Fly B737 Max8 and Lufthansa A319, using interoperable GBAS GAST C avionics.
Frankfurt ISGS (December ‘21 to May ‘22) with Lufthansa commercial aircraft (A320 family) using GBAS GAST C, in conditions down to CAT II. Objective is to gain experience with GLS CAT II operations in an ATC environment. A prototype GAST-D ground station is also installed at Frankfurt and has been used for preliminary tests with the EUROCONTROL MMR in preparation of Demo #1.
Roma Ciampino ISGS (November ‘21 to March ‘22), with Dassault Falcon & Honeywell Embraer 170 test aircraft and using RNP SBAS approaches with steeper glide slopes (3.9° and 4.4°).
Twente ISGS (February to June ‘22), with NLR test aircraft and using RNP SBAS with 3.5, 4.0 and 4.49° slope angles, with the objective to assess the dual PAPI solution, serving the conventional and increased glide slope.
Live trials at EHTW/ENS Twente airport (NL)
The demonstrations at Twente, a non-commercial airfield, took place during the first week of October with the goal of evaluating in real visual conditions the runway dual markings and dual PAPI as necessary for SRAP and IGS-to-SRAP approaches, in line with the PJ.02 solution requirements. The prep work had been done earlier in 2021 within PJ02 when EUROCONTROL and Lufthansa Aviation Training used an A319 simulator at Frankfurt with airline pilots to run three flight simulation campaigns on approach procedures in different visibility and weather conditions including SRAP, ISGS and IGS-to-SRAP.
The existing runway markings on Twente’s Runway 05 were expanded for Demo #1 with a second (ICAO compliant) set of markings, consisting of a second threshold, touchdown and aiming point markings, located 1,020 metres further, together with a second PAPI on the opposite side of the runway. The approach trials were based on GBAS GAST-D temporary ground station, supporting different GLS published approaches with 3.0, 3.2, 3.5, 4.0 and 4.49 degrees glideslope.
The NLR test aircraft (a Cessna Citation II) was equipped with two GAST-D receivers and made a large number of approaches (8 days with 6–20 approaches per day) for data acquisition and pilot evaluation purposes. A different guest pilot each day was asked to fly the approaches.
The Lufthansa and TUI fly aircraft evaluated visual aspects, flyability and gathered performance data on the 3.0 and 3.5° approaches to both thresholds.
The preparation of the demonstration also provided valuable insight into regulatory aspects, such as the GBAS frequency allocation process, approval aspects of the systems and planned flight operations, as well as the necessary infrastructure preparations. The findings will feed into both the regulatory work package and the next trials.