8th July 2019

An automatic landing system for small aircraft

German researchers have created an onboard, automatic landing system for small aircraft. This can function without the need for any technology on the ground, and could lead to a new era of safer, autonomous flight.

Automatic landings have long been standard procedure for commercial aircraft. While major airports have the infrastructure necessary to ensure the safe navigation of the aircraft, this is usually not the case at smaller airports. Researchers at the Technical University of Munich (TUM) and their project partners have now demonstrated a completely automatic landing with vision assisted navigation that functions without the need for ground-based systems.

At large airports, the Instrument Landing System (ILS) makes it possible for commercial aircraft to land automatically with great precision. Antennas send radio signals to the autopilot to make sure it navigates to the runway safely. Procedures are also currently being developed that will allow automatic landing based on satellite navigation. Here too a ground-based augmentation system is required.

However, systems like these are not available for general aviation at smaller airports, which is a problem in case of poor visibility – then aircraft simply cannot fly. "Automatic landing is essential, especially in the context of the future role of aviation," says Martin Kügler, research associate at the TUM Chair of Flight System Dynamics. This could apply for example when automated aircraft transport freight and, of course, when people use automated flying taxis.

In the project "C2Land", supported by the German federal government, TUM researchers have partnered with Technische Universität Braunschweig to develop a landing system for smaller aircraft without assistance from ground-based systems.

The autopilot uses a GPS to navigate. The problem: these signals are susceptible to measurement inaccuracies – for example, due to atmospheric disturbances. The GPS receiver in the aircraft cannot always reliably detect such interferences. As a result, current GPS approach procedures require pilots to take over control at an altitude of no less than 60 metres and land the aircraft manually.

In order to make completely automated landings possible, the TU Braunschweig team designed an optical reference system: a camera in the normal visible range and an infrared camera that can also provide data under conditions with poor visibility. The researchers developed custom-tailored image processing software that lets the system determine where the aircraft is relative to the runway, based on the camera data it receives.



Credit: TU Braunschweig

The TUM team developed the entire automatic control system of TUM's own research aircraft, a modified Diamond DA42. The plane is equipped with a Fly-by-Wire system enabling control by means of an advanced autopilot, also developed by the researchers.

To make the landings as accurate as possible, additional software functions were integrated – such as comparison of data from the cameras with GPS signals, calculation of a virtual glide path for the landing approach as well as flight control for various phases of the approach.

The team was able to watch as the research aircraft made a completely automatic landing at the Diamond Aircraft airfield. Test pilot Thomas Wimmer is completely convinced by the landing system: "The cameras already recognise the runway at a great distance from the airport. The system then guides the aircraft through the landing approach on a completely automatic basis and lands it precisely on the runway's centreline."



Credit: Andreas Dekiert / C2Land

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