Future Advanced Air Mobility – The next big challenge for GNSS & GeoSpatial industries

Graeme Hooper Managing Director GPSat Systems

The Paris 2024 Olympics is evolving as the first mainstream event to showcase the broad-scale usage of crewed Advanced Air Mobility (AAM) to transport passengers around the city. Apart from the usual athletic competitions in the field, eVTOLs from Volocopter, Ehang, Joby, Eve, and Lilium etc, will potentially be the other high visibility competition that captures global interest. Ushering in the future of new forms of urban transportation, for senior executives and other luxury seeking guests, ferrying passengers from downtown city centre vertiports out to large outlying international airports.

While much global media attention has focused on eVTOL aircraft development for future electric environmentally sustainability, very little has been written about the supporting vertiport infrastructure development and regulatory planning / certification required. However, this is about to change as Melbourne city Australia in late 2023, also introduced a bold new vision to be an early developer/ adopter for supporting AAM infrastructure development and certification. Stimulating job and expertise growth in this new and vibrant adjunct industry.

For those of us in the geospatial and navigation industries what does this future opportunity mean? For some it represents a huge fresh “green field” opportunity to finally blend existing high fidelity city-wide 3D building geospatial surface models with those of multiple eVTOL aircraft, into advanced 3D Spatial Artificial Intelligence (3D-SAI) environments. Real time 3D-SAI delivering essential information into Augmented Reality pilot wearable headsets providing critical 3D spatial situational awareness. This type of technology has been a huge part of 3D games for decades, but now, there is finally a solid need to breakout this SD-SAI technology out of the gaming universe and introduce it into real world broadscale usage. Real time 3D high fidelity situation awareness of the spatial relationships between multiple operational urban AAM aircraft operating in close proximity near the vertiports and static surrounding urban building structures will be safety critical. City / urban planners and government aviation regulators will need to work closely to devise operational corridors and new flight operations regulations/ Minimum Operational Procedures (MOPs). Potentially, a huge force driving rapid growth in navigation and geospatial sciences jobs and expertise.

There is also a huge precision navigation industry need. Arguably only radio based navigation technologies such as GNSS etc, will be sufficiently evolved to deliver the necessary precision positioning in the tightly confined flight corridors. To over come reduced satellite visibility due to terrain and urban obstructions, multi constellation GNSS (GPS, Galileo, Beidou) and possibly 5G navigation sciences will be required. Aviation industry will need to cease sole reliance on GPS and embrace both Galileo, Beidou and possibly 5G to maintain signal availability. The other important factor here, is that a very significant percentage of eVTOL development is being undertaken by countries outside the US (Europe, Japan, China etc.), so they’ll be keen to incorporate local sovereign navigation infrastructure in their certified flight operations.

The obvious challenges for GNSS / radio based navigation operating in these RF congested environments is the threat of intermittent RF Interference. In the short term, eVTOL assured navigation will be augmented with contemporary MEMS IMUs, however, their holdover limitations for a few minutes in dynamic vibration environments means they can’t be used exclusively for high Safety and Integrity navigation in piloted eVTOL applications. Alternate sole / primary navigation utilising Quantum IMUs may become significant in the far future, but mass production and affordability won’t be achieved anytime soon.

So for now, irrespective of which radio based navigation sensor technology is adopted as a primary PNT function, other supporting GNSS RADAR technologies for RFI signal detection and source geolocation will be essential ingredients for safe urban vertiport operations. Effectively policing the RF spectrum environs particularly in the critical vertiport departure and arrival terminal areas, will be essential. The output of such a system will be instantaneous regional RF Spectrum SA 3D heatmaps, delivered in real time to future pilot 3DAR headsets. Quantifying where the problem RFI areas are, and how/ where to approach intended a vertiport safely, substantially minimising RFI effects to eVTOL flight operations. Like eVTOL aircraft development, these supporting GNSS RADAR technologies (GRIFFIN) will also enter the market in 2024.

For the geospatial and navigation professionals, all future flight approach and departure corridors designs will require detailed 3D modelling and navigation vulnerability assessments before final flight certification. Vulnerability flight assessment/ modelling will need to be performed in high fidelity 3D synthetic simulated environments well before actual flights are allowed. Matching different aircraft operating constraints/ characteristics to the intended urban vertiport environments. Different buildings with their metalized glass/ façade surfaces will need to be assessed for both GNSS signal multipath sources and signal obscuration will also need to be included the 3D synthetic simulation mix.

Fortunately, the GNSS industry already has the required laboratory GNSS signal simulation equipment available and is routinely used by the existing avionics industry to perform this type of work. What’s new, is the need to combine advanced 3D building induced multipath propagation models that combine RF Ray Tracing source from the high fidelity urban 3D geospatial models. These GNSS simulation tools also have the ability to inject multi source RFI threats into the synthetic modelling sequence. So fortunately, with modern computers and the right GNSS simulation tools, all vulnerability and certification assessment work can be effectively completed from the comfort of an office. Well before needing external validation of real eVTOL flight trials.

However, to fully support global eVTOL / vertiport vulnerability assessment / development there is a need for real world urban environment building induced wind turbulence analysis and the effects it will have on vertiport operations, impacting multiple aircraft in congested airspace. The good news here is that the civil/ construction urban planning community have these advanced 3D wind models already available. Just like RFI threats the GNSS simulation equipment manufacturers will need to incorporate this 3D information into their synthetic simulation tool suites.

Presumably, for defining future eVTOL dynamic corridor flight paths/ tunnels, the new analysis work will require GNSS signal availability overlayed with RF Multipath, RF Interference, plus changing wind hazards will all need to be combined during detailed 3D analysis. Certainly, exciting times for both the 3D navigation, geospatial communities and avionics manufacturers all working together to deliver safe future AAM flight operations in global city environments.