Safe landings without navigation aids on the ground Research aircraft successfully demonstrates automatic landings with optically assisted navigation

The Technische Universität Braunschweig and the Technische Universität München, together with the aircraft manufacturer Diamond Aircraft Industries GmbH (DAI), have for the first time demonstrated fully automatic landings with optical-assisted navigation. At the DAI home airport in Wiener Neustadt, the fly-by-wire research aircraft, a modified Diamond DA42, successfully flew fully automatic approaches and landings. The flight guidance system of the TU Munich used sensors of the TU Braunschweig, which monitors the primary satellite-based position determination of the aircraft online with the help of an on-board autonomous camera system.

Today, fully automatic landings in commercial aviation are only carried out under very poor visibility conditions and using complex ground infrastructure. Without such systems on the ground, aircraft can only be brought up to a minimum height of 200 ft to the runway by autopilot with satellite navigation. From this altitude on, the pilot must take over the relative positioning, state determination and control of the aircraft and carry out the landing independently.

Nevertheless, automatic landings are very attractive for commercial as well as for general aviation, and sometimes even indispensable for unmanned flight systems – especially if expensive infrastructure on the ground can be dispensed with. Precise positioning, control and reliable integrity monitoring are indispensable. As part of the “C2Land” research project, researchers at Technische Universität Braunschweig and the Technische Universität München have developed a landing system that can meet these requirements.

For this purpose, the conventional satellite-based navigation was extended by an optical system. Using cameras operating in the visible and infrared ranges, as well as specially developed image processing techniques, the runway is optically detected and the relative position of the aircraft is determined. With the aid of optical positioning, independent on-board autonomous integrity monitoring of the satellite-based navigation system – especially below the previously valid minimum altitude of 200 ft – is ensured. “The optics detect the runway at a great distance from the airfield. The landing system then guides the aircraft with optical navigation along the approach and lands it precisely on the runway centerline,” reports DAI test pilot Thomas Wimmer, who tested the automatic landing system in the DA42 research aircraft at the Technical University of Munich during the final demonstration flights.

Flight testing of the navigation system with the research aircraft of the TU Braunschweig

Several flight test campaigns were also carried out in advance by the Institute for Flight Guidance (IFF) at Braunschweig Research Airport with the help of the Institute’s own Dornier Do 128-6 research aircraft. Various landing approaches were first flown manually in order to develop and validate the image processing algorithms with the recorded data.

The IFF thus continues decades of efforts to increase safety and efficiency in air traffic. As early as 1989, the Institute carried out the world’s first fully automatic landing based on satellite navigation. This was followed by developments to increase the positioning accuracy of satellite and inertial-based navigation systems. “The optical system enables us to process complex image information automatically. In this way we create redundancy in position determination and thus contribute to increasing situational awareness. This can help us to make the most critical phase of a flight – the landing – even safer,” says Stephan Wolkow, technical project manager of the “C2Land” research project.

 About the C2Land research project

Since 2013, within the framework of the project “C2Land”, funded by the Federal Ministry for Economic Affairs and Energy (BMWi, FKZ 50 NA 1601), research has been carried out on a novel automatic landing system for general aviation. The IFF team, consisting of Dr. Ulf Bestmann, Stephan Wolkow, Maik Angermann and Andreas Dekiert, has developed a navigation system with optical-supported positioning. The flight guidance and flight control systems, which control the aircraft during automatic landing, were developed at the Institute of Flight System Dynamics (FSD) at the Technical University of Munich.

The industrial project partner f.u.n.k.e. AVIONICS GmbH has designed a cockpit display for the pilot to operate and monitor the landing system. In addition, the project partner has developed a subsystem for collision avoidance that automatically monitors the airspace and initiates an evasion maneuver if required. Another project partner messWERK GmbH evaluated automatic guidance for the class of ultralight aircraft.

The composite aircraft manufacturer Diamond Aircraft Industries GmbH supported the project as associated partner during system integration and flight tests with the Fly-by-Wire research aircraft of the Technical University of Munich.