Published On: January 27, 2021By

OBeLiSk – Integrating High Altitude Aircraft into German Airspace

Konstanz, 27th January 2021 – Unisphere is proud to contribute to the integration of high-altitude aircraft into German airspace.

In recent time, high altitude aircraft, commonly known as HAPS (high-altitude pseudo-satellites) operating in the stratosphere at 20km altitude have reached a level of maturity which indicates first operational services in a few years.

“A HAPS can be as large as a jumbo jet with the weight of a mid-size car, the power of a scooter flying at the speed of a cyclist. When crossing the altitude bands of today’s airliners during ascend and descend, they are a significant challenge for air traffic control.” said Michael Anger, founder of Unisphere.

HAPS combine the capabilities of aircraft and satellites in a unique way. They have the persistency to loiter uninterrupted for a long time while being able to alter flight missions and allow for payload exchange, modifications or repairs between flights which enables new applications in earth observation and telecommunication.

Within OBELISK, experts from private industries, research organizations, and government have joint efforts to develop concepts and procedures to integrate HAPS into the busy European sky.

“Unisphere will simulate 4D trajectories of HAPS flights with our Flight Management Platform. We combine data from the German Meteorological Service with aircraft performance models. This allows the German Air Traffic Control to identify challenges of airspace integration without the need to fly a HAPS.” said Christoph Schlettig. “Our operational experience from managing the Solar Impulse flight around the world around the world is another input to OBELISK.” Anger added.

press release OBELISK

The full press release can be found below.

OBeLiSk optimizes the use of high-flying pseudo-satellites

Braunschweig 25.01.2021

One of the first operational concepts for the safe and efficient integration of high-altitude pseudo-satellites (HAPS) into airspace is being developed and validated as part of the OBeLiSk project. The team behind the project brings together organisations from the private sector (Leichtwerk Research and Unisphere), State-owned entities (the German air navigation service provider (DFS) and the German Meteorological Service (DWD)) and the university sector (TU Braunschweig, Institute of Flight Guidance). The project aims to enable the provision of information from high altitudes across Germany. Funding for the project is being provided by the German Federal Ministry for Economic Affairs and Energy (BMWi) as part of its aeronautics research programme.

What are HAPS?

A high-altitude pseudo-satellite, also known as HAPS, is an unmanned aerial vehicle that travels in the stratosphere. They are fully automated systems and are, simply put, satellites that travel much closer to the earth than conventional satellites. Due to their high local loitering capability and their proximity to the earth, they can be used for observation purposes and telecommunication applications. They can provide important intelligence day and night and could be used, for example, for search and rescue missions, disaster relief, monitoring of environmentally relevant events, or in agriculture. HAPS can also make a flexible and efficient contribution to extending the coverage of the 5G cellular network across Germany.

The special flight performance of high-altitude pseudo-satellites in terms of speed, climb and descent rates, and long flight duration require careful and thorough flight planning. Changing weather conditions, however, pose a particular challenge, requiring continuous and efficient optimisation of route planning during the flight. For this task, the project partners want to develop concepts, procedures and rules for the dynamic operation of HAPS. Special consideration will be given to the requirements of operators for route planning and optimisation, as well as the optimisation of the controller's working position. These human-machine interfaces improve working relationship between digital technology and air traffic control personnel.

"With the OBeLiSK project, we want to demonstrate a flight planning option that takes into account the requirements for stability and reliability. For the first time, we are enabling an automatic negotiation of flight plans between the HAPS and air traffic control," said Thomas Krüger from Leichtwerk Research in Braunschweig, Germany. "These developments are fundamental for the economic and safe operation of HAPS in the future," continued Krüger.

DFS Deutsche Flugsicherung GmbH, the German air navigation service provider, is a State-owned company under private law with 5,600 employees as at 30 June 2020. DFS ensures the safe and punctual flow of air traffic over Germany. Around 2,200 air traffic controllers guide up to 10,000 flights in German airspace every day, more than three million movements every year. This makes Germany the country with the highest traffic volume in Europe. The goal of the activities in the OBeLiSk project is to create an operational concept for the smooth integration of high-altitude pseudo-satellites (HAPS) into German airspace. This will be validated by means of real-time simulation at the end of the project.

Leichtwerk Research GmbH, based in Braunschweig, Germany, is a service provider for high-end research and development projects in the field of aerospace technology. Its service spectrum encompasses the development and construction of manned and unmanned aircraft systems, innovative lightweight structures, as well as the development of flight operation procedures and human-machine interfaces. The goal of the OBeLiSk project is to develop and validate a control centre for HAPS to plan, negotiate and monitor coordinated flight plans.

The German Meteorological Service (DWD) is a federal authority and reports to the German Federal Ministry of Transport and Digital Infrastructure (BMVI). It is responsible for the safety of air traffic in Germany as regards meteorology. Within this complex area of responsibility, meteorological processes are recorded, analysed and forecast. The DWD operates an extensive meteorological observation system and a computer centre to run its numerical weather prediction model. Thanks to this infrastructure, the DWD can offer products tailored to the requirements of a range of aviation users. One of the purposes of this project is to expand the product portfolio for drone users.


Unisphere GmbH specialises in flight path forecasting for HAPS, air taxis and drones. Unisphere supported Solar Impulse in its first successful round-the-world flight in a solar-powered aircraft. Unisphere's objective is to create a flight management platform for the flight path optimisation of HAPS. It integrates the current weather, weather forecasts, the airspace structure and detailed flight performance models for unmanned systems. HAPS can be operated in a highly automated and economic manner by using simulated 4D trajectories and the pilot knowledge embedded in the software.


The Institute of Flight Guidance (IFF) is part of the TU Braunschweig (Technical University Braunschweig). The institute is engaged in research and teaching in the fields of navigation, air traffic management, flight measuring technology as well as flight guidance systems and control. The overall goal of research at the IFF is the development of the methods and technical means to support people in the safe execution of flight guidance tasks. This is reflected in the IFF's goals as a project partner in the OBeLiSk project, namely to enable interoperability between HAPS and future air traffic control concepts. The requirements for air traffic control concepts and HAPS will be formulated to enable safe and effective operation of HAPS. In the further course of the project, the required concepts and human-machine interfaces will be implemented using prototypes and validated using demonstrators.