Thomas Bögl

Technology in action

It solved the chicken-and-egg problem

Interview with Thomas Bögl, Director of Technology and Studies

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Updated on 13-May-2024 🛈
Originally published on 01-Apr-2023

The L band digital aeronautical communications system (LDACS) officially kicked off in December 2016 when the International Civil Aviation Organization in Canada began drafting standards. Years of groundwork went into reaching this milestone. Hardly anyone knows this better than Thomas Bögl. The Director of Technology and Studies at Rohde & Schwarz clearly saw the need for a long-term digital expansion of the analog aeronautical radio standard already in the late 2000s.

Bögl worked with Thomas Richter, a senior engineer from predevelopment, and his department to launch R&D projects inside the company while making contacts at research institutions such as the German Aerospace Center (DLR). He was also prepared to fly 6 000 kilometers from Munich to the International Civil Aviation Organization (ICAO) headquarters in Montreal, Canada at the drop of a hat.

Mr. Bögl, when did you start working on LDACS?

I first heard about LDACS in 2010 at a DLR meeting in Oberpfaffenhofen. DLR helped create the LDACS waveform. The DLR experts made a very convincing case that new digital waveforms were needed to ease pressure on analog voice communications. New products were clearly needed. Since the DLR does not develop products itself, a collaboration between research and industrial partners made a lot of sense. The meeting was also the beginning of a highly productive aeronautical research (LuFo) project partnership with the DLR.

Analog voice communications have long proven their worth in ATC communications. Where did you see signs that it had reached its limits?

Today, air traffic controllers handle almost as many aircraft as they did before COVID-19. And the numbers are growing rapidly. We could see this trend 15 years ago. Another factor is that hiring more employees to shoulder the workload is not possible – there are simply not enough parallel voice channels.


Rohde & Schwarz is the only company said to be interested in supplying LDACS products for aircraft and ground infrastructure


Thomas Bögl, Director of Technology and Studies

The only way to relieve pressure on the system is to create a parallel data link for instructions that do not require direct voice communications between pilots and air traffic controllers, such as non-safety instructions when the aircraft is still on the ground. Of course, VHF data link technology has been around for years but it has limited data throughput and cannot effectively relieve voice communications over the medium or long term. It soon became clear that aviation would need a more powerful digital data link technology.

LDACS also opens new use cases. Which are the most important ones and why?

The first and most important use case is providing sufficient data rates and encryption in existing systems. LDACS in the L band will be a powerful sibling to existing VHF data link. An LDACS data link is like a quasi broadband VHF data link, making it relatively easy to expand existing systems.

LDACS also has its own navigation function. If GPS or other navigation systems are unavailable to an aircraft, LDACS can act as a backup system and provide positioning information. LDACS boosts efficiency in aeronautical radiocommunications, while also helping to improve aviation safety.

Your work required you and your team to travel to Montreal to the ICAO headquarters very early on. Why not go to the European regional office in Paris or to the German air navigation service provider (DFS)?

The members of the ICAO communications panel meet solely at the headquarters. Only they have the power to create new working groups with a mandate to standardize new aviation technologies. DFS uses technologies that are approved for air traffic control, but it is not authorized to carry out standardization work on its own.

International Civil Aviation Organization (ICAO) headquarters in Montreal.

Generally, airlines and airport operators do not invest in new technology until new equipment is nearly ready for the market. And component and equipment manufacturers want to see that a market exists before investing in development. Was your visit to the ICAO also vital to solving this traditional chicken-and-egg problem? Once a decision is made at the highest level, everyone has planning certainty.

Yes, our visit to the ICAO solved the chicken-and-egg problem and marked the start of international targeted LDACS activities. A forum was quickly created with the establishment of a new technology working group, where anyone interested and affected by LDACS could officially meet and share ideas. It also served as a base for activities that looked beyond standardization work.

The Avionic Task Force was founded and, working under the ICAO mandate, it brought together all of the companies involved in aviation systems to identify and overcome any remaining hurdles. Thomas Richter is in charge of this working group. As the project leader for LuFo projects at Rohde & Schwarz, he planned and organized the flight trials. He played an important role in LDACS happenings. Without his tireless commitment, the many LDACS activities at Rohde & Schwarz would not have been possible.

Which organizations and agencies need to cooperate to successfully introduce global standards such as LDACS?

The ICAO and EUROCAE are the most important. However, major air navigation service providers such as EUROCONTROL also play a role since they provide the formal basis for rolling out and operating a new system. Future operators and LDACS users are also very important. Airlines and aircraft manufacturers need to signal their interest in a system and convince companies to invest a share of their R&D budget and reach the point where products can actually be marketed.

A five-member team headed off to Montreal back then. How has interest in LDACS evolved since?

Some 200 companies and organizations attended one of the latest LDACS webinars organized by the DFS. They are learning about LDACS while pursuing their own activities here. Despite the growing competition, Rohde & Schwarz is the only company said to be interested in supplying LDACS products for aircraft and ground infrastructure.

What has been your biggest motivation over the past 15 years?

Several things. One is that the international aviation community has taken up many of our LDACS proposals. For example, we have shown how to cost-effectively expand aircraft and ground installation infrastructure with LDACS. I am also pleased to see many companies and organizations talk to us about the technology. We are considered a top authority here.


Of course, field trials in April 2019 were an absolute LDACS highlight when we installed an LDACS demonstrator in the DLR research aircraft to show what the new waveform could do live and in flight.


Thomas Bögl, Director of Technology and Studies

The first test flights in 2019 were routed over four LDACS ground Stations that were specially set up for this project in southern Bavaria. The flight paths were planned to allow testing of the handover process...

…as well as various triangulation scenarios using two to four ground stations.

Of course, field trials in April 2019 were an absolute LDACS highlight when we installed an LDACS demonstrator in the DLR research aircraft to show what the new waveform could do live and in flight. We set up four LDACS ground stations in southern Germany and the aircraft onboard system successfully communicated with the stations during the flight.

The DFS granted all necessary approvals for realistic test flights. We could then fly through airspace along with normal air traffic. These were first flights to demonstrate LDACS live, generating a huge media response. That day the DLR website did not have any reports about Mars missions or the ISS but focused entirely on the LDACS test flights for our project.

As an engineer, how do you cope with the bureaucracy of standardization?

I am in fact involved with the technology, but with a special focus on the usability and economic efficiency of future solutions. These two aspects are very important. If a new technology has little customer value, no one will buy it. And if the technology does not work and is financially unappealing, it will never be introduced in the first place. Even exceptional customer value can’t help in such a case.

Yes, standardization work can be very bureaucratic. We basically share this work with the DLR and the DFS. Both are partners in the current LuFo project PaWaDACs. They also both play a key role in the standard committees at the ICAO and EUROCAE. The division of labor lets us focus on the technology and customer benefits, while the DLR and the DFS include our results in the standards.

How would you sum up what you have achieved so far? And what do you see as the next major milestone for LDACS?

I am very positive about our achievements. Right now, many different parties are interested in LDACS. Standardization should be completed in the next calendar year. The main requirements for us as a company are fulfilled. This means we can have the right products available for the projected market launch in 2028 and tap even further into the civil avionics market.

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