Aerospace and defense technology group Thales has been focused on the advanced air mobility (AAM) sector for five years, mainly with a view to how it can support the transformational changes that the new aircraft and operating models will bring to airspace management. Much of its expertise, especially drawing on extensive work with advanced military unmanned air systems (UAS), is being applied to the challenges and opportunities with the advance of autonomous aircraft.
“We’re convinced that in the future unmanned and manned flights will happen in a very harmonious way, but there are big challenges,” Thales Airspace Mobility Solutions vice president Todd Donovan told FutureFlight. “It will become more of a machine-to-machine solution, supervised by humans, but we don’t know how long it will take to do it in a safe manner.”
Thales is looking to apply the lessons it has learned from implementing air traffic management (ATM) solutions for UAS to the more complex aircraft anticipated for applications such as eVTOL aircraft. While acknowledging that most early eVTOL aircraft pioneers expect to start operations with a pilot on board, the company sees a convergence of UAS and piloted aircraft technologies as the industry progresses towards full autonomy.
For instance, the work Thales and Elbit have done in developing the Watchkeeper intelligence, surveillance, and target acquisition drone for the British Army has provided a useful template for some aspects of the task of integrating UAS into non-segregated airspace—i.e the airspace that autonomous eVTOL air taxis, for example, would have to share with aircraft with a pilot on board. The Watchkeeper fleet has operated in civilian airspace, having been fitted with transponders and the ability to interact with ATM systems, including verbal interactions between air traffic controllers and the drones’ ground-based remote pilots.
“When we talk about larger vehicles that could carry cargo and people, there will be further challenges, and we think initially these will be equipped more like helicopters to be interoperable with today’s air traffic control systems,” Donovan said. “But they will have to carry a higher safety certification standard because there will be no pilot on board to take over if there is an issue.”
Cybersecurity is another challenge that Thales feels the need to address. The company believes there needs to be a high degree of trust that when machines are interacting with other machines the operational data they are exchanging cannot have been corrupted.
According to Donovan, significant changes are coming to the way airspace is used. “When you look at airspace today it is largely in blocks and it is largely static, such as the class B airspace around airports with its own set of rules,” he said. “It is going to move from this to being micro-segmented, and today’s systems don’t address this.”
As a global aerospace and defense group, France-based Thales is looking to leverage its presence in multiple countries that are trying to address the challenges of reshaping their ATM infrastructure to accommodate the expansion of AAM operations. Its approach is to engage in multiple projects around the world to be close to how different technological and operational concepts are emerging and how these can be shaped to local environments.
One example of this approach is in North Dakota, where a team from Thales is working with several partners, under the supervision of the FAA, to prepare the way for the approval of beyond-visual-line-of-sight drone operations. According to Donovan, the sparsely populated state is a good place to start early, small-scale operations that don’t necessarily have to take account of all aspects of detect-and-avoid capability.
Meanwhile, in Europe, Thales expects to have a prototype of its aircraft collision avoidance system (ACAS) ready to support flight testing by the end of 2021. The work is part of the group’s efforts to support the safe integration of smaller unmanned aircraft systems (UAS) into both segregated and non-segregated airspace that it sees as a key step in the eventual introduction of larger autonomous aircraft.
“With new eVTOL aircraft and urban air mobility coming, we will have a larger mix of aircraft in both segregated and non-segregated airspace, and so anti-collision capability is important,” explained Marie-Pierre Guilbert, product line manager with Thales Communication & Security. The company has been contributing to work supported by both the FAA and Eurocontrol to adapt ACAS technology for use with autonomous aircraft.
One key requirement when integrating UAS into non-segregated airspace alongside piloted aircraft is that both types of traffic be able to see and avoid each other. “We need these [autonomous] aircraft to coordinate with and be interoperable with all other airspace and so the approach has to be standardized,” Guilbert told FutureFlight.
In late 2020, following work with the Radio Technical Commission for Aeronautics in the U.S. and Eurocae in Europe, minimum standards for ACAS equipment to be used by UAS were agreed to and designated as “Xu” (to differentiate them from “Xa” for standard air transport operations). Minimum standards for smaller UAS ACAS “sXu” and for Rotorcraft “Xr” are currently under definition and standardization. Implementation dates for these standards still need to be agreed upon by aviation safety agencies on both sides of the Atlantic.
Some of Thales’s most significant work in this area has been done through Eurocontrol’s SESAR (Single European Sky ATM Research) body and the Massachusetts Institute of Technology has been involved in the development of the algorithms to support the expansion of ACAS to autonomous aircraft operations. The air traffic management agency provided Thales’s engineers with more than one million potential collisions from real flight data so that it could conduct extensive simulations.
Guilbert explained that the new ACAS format will require aircraft to be fitted with both cooperative sensors (like those used in existing traffic collision avoidance systems or the radio function of air traffic control systems) and a non-cooperative sensor, such as radar, or an optical or infrared sensor. For the cooperative sensor, Thales could provide an adapted version of its existing hardware, such as a Mode S transponder. The input from the sensors is fused together by the algorithms developed by Thales.
According to Thales, the XU prototype ACAS that it intends to evaluate in trial flights with various partners is based on design assurance quality level B with some parts of the system, such as the processor, being to level A standards already in service with commercial aircraft. One of the program’s partners is Safran, which will provide its Patroller surveillance UAS, which is designed to carry a 250 kg payload and operate autonomously for up to 20 hours.
Beyond the initial trials, Thales intends to test the new ACAS with other aircraft. Guilbert said it has been in touch with several manufacturers, including Leonardo, which is considering the technology for its Falco UAS.
However, beyond the technology, Donovan stressed that the AAM industry will need to do far more to convince the general public why it should accept autonomous aircraft flying above its communities. “People are worried about noise, safety, and privacy, and there will need to be a far greater engagement with communities,” he concluded.
