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Synthetic vision for advanced air mobility

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Recent advances in aeronautical databases enable a safer future for aviation.


By Sean Connor
Director of Unmanned Systems Discover Technology Intl

The certified Saab-Maxar ultra-photorealistic 3D image terrain and elevation data of Manhattan from 7000 ft AGL provides an unparalleled perspective of the urban environment for low-altitude operations, improving situational awareness for helos, drones, and UAM operators.
When we think about the future of aviation, we like to imagine a world where flying cars are as common as today’s automobile, offering the luxury of intercity travel without the headaches of rush hour traffic and undeserved parking tickets.

Until recently, this future looked to be a distant fantasy left for old Hanna-Barbera cartoons and Hollywood movies. Industry disruptors like Uber have sparked new interest and debate around air travel, helping legitimize the concept of urban air mobility (UAM).

In 2020, Toyota set its sights to the sky, investing $394 million into Joby Aviation to launch an electric vertical take-off and landing (eVTOL) aircraft. This year alone has already seen 6 multi-billion-dollar deals among UAM companies.

And traditional OEM players like Airbus, Boeing, and Bell are all involved in new “air taxi” certification programs, which indicates serious commitment to the space.

However, even as we embrace these concepts of revolutionary change in urban flight, the demands for new certification and rulemaking can be sure to produce delays in meeting the future, setting us on course for a more routine reality – one where small and incremental, yet significant, technological advances are being made to foster a safer and more efficient industry for manned aviation within months and years, not decades.

A new global image and terrain database standard

A key element of these concepts is aeronautical databases, which are essential to driving next-generation synthetic vision systems (SVS), advanced flight displays, superior navigation systems, and, ultimately, the foundation for an unmanned traffic management (UTM) infrastructure.

VTOL
Embraer’s Eve eVTOL

One such solution emerged at the National Business Aviation Association Conference and Exhibition (NBAA–BACE) in Las Vegas in 2019. Saab, in partnership with Vricon (later acquired by Maxar), announced the rollout of a new high-resolution 3D global terrain database.

Vricon holds the world’s largest source of archive satellite data. Combining those archives with Saab’s unique multi-view stereo algorithms, the database is able to deliver 3D elevation data sets with accuracy better than 3 meters (~10 ft), with no ground control points required.

The production process is also capable of generating database tiles at 0.5-meter resolution, which can include photorealistic imagery layered on 3D elevation. This level of quality and accuracy offers the potential to be a game changer for both the manned and unmanned aviation industries, presenting new levels of situational awareness, safety-critical information, and mission intelligence.

Stepping into the world of aeronautical data services may be new territory for Saab, but, as an aviation supplier offering modern flight deck solutions, leveraging its own in-house technology creates an opportunity for meeting a broader set of future market needs.

“Our aim is to deliver the most advanced and reliable flight deck systems to support our customers high safety standards,” says Jan Widerström, VP of Saab Avionics Systems. “Our high-resolution 3D global terrain database brings to market the new standard for advanced flight displays and offers a technology that supports the future of both manned aviation and urban air mobility operations.”

Visual comparison of today’s DTED standard (top) with the Saab certified aviation DTED (below) shows significant improvement in resolution and accuracy.

Limitations of the past

The use of synthetic vision displays is actually fairly new to business aviation, and is in the early stages of becoming a primary tool for the drone and UAM industries. Early SVS flight instruments began to appear between 2000 and 2005, and most were limited in the level of scene detail, other than basic terrain.

However, now that SVS flight displays are more or less standard on the modern flight deck, there is an increasing reliance on their applications for multiple phases of flight.

Whether being used for a low-visibility approach, helicopter emergency medical services (HEMS), or now even autonomous drone delivery, that reliance demands a higher-performance system.

When it comes to terrain databases, avionics systems have been stuck with data that is 20 years in the past. Traditional aeronautical databases integrated in today’s terrain awareness and warning systems (TAWS) and SVS rely on NASA’s decades-old Shuttle Radar Topography Mission (SRTM) data, which is widely known to have major limitations – it lacks detail and resolution in lower altitudes, it’s often incomplete in many geographic locations, and only meets minimum FAA regulatory requirements, presenting end-users with technology that fails to meet the demands of today’s flight operations.

Typical digital terrain and elevation databases (DTED) built on the SRTM mission data are at best offering 30-meter (1 arcsec) resolution in certain locations, although most are still relying on 90-meter (3 arcsec) data, which creates constraints and safety concerns for low-altitude operations.

These discrepancies leave avionics suppliers with the manually intensive and expensive process of having to combine multiple sources in order to offer OEMs and operators a complete database that meets their operational requirements.

Furthermore, there are coverage and accuracy issues that affect operational efficiency, constrain mission readiness, and can lead to accidents. Take for example the 2012 crash of a Royal Norwegian Air Force Lockheed Martin C-130J Super Hercules into Kebnekaise, the highest mountain in Sweden.

Although the investigation’s initial findings for the cause were assigned to crew error during tactical low-level flying, it was later determined that the C-130J TAWS was not equipped with information about the terrain in Sweden. Kebnekaise is located at 68° N, and there are known to be gaps in the available terrain data beyond the 60th parallel.

Historically, natural obstacles and man-made structures have also been an issue for helicopters and business aircraft, and are now on the radar for the drone and air taxi markets. In most cases, obstacles below 200 ft are not required by industry standards.

For low-altitude helicopter and UAM operations, however, it is crucial to know where these obstacles and structures are located. Some supplemental sources have been integrated with today’s SVS and helicopter TAWS (HTAWS), such as powerline and windmill pole locations, but an additional concern is related to inaccuracies that can lead to reduced safety and a fatal outcomes.

Computing power and storage capacity have also been 2 driving factors limiting the full potential of SVS and other flight displays to date. Graphics processing units (GPUs) and graphics cards in legacy systems could only support so much data processing, and therefore lower-resolution databases became the norm.

But even as new avionics hardware computing and software capabilities have been introduced into the cockpit, a higher-performance database source hasn’t been available to integrate with, mainly because it didn’t exist – until now.

New database technology by Saab and Maxar delivers 3-meter accuracy and 0.5-meter resolution with photorealistic 3D elevation imagery, giving pilots greater performance for SVS displays and for TAWS.

The future of SVS and advanced flight displays

Demands of the modern flight deck in business aviation are changing. Pilots and executive passengers want the latest technology for their aircraft to ensure that they can get where they need to go on time and on demand.

What Saab’s new solution offers to business aviation – and the broader aviation industry – is the most accurate and highest resolution visual terrain database seen to date.

This new capability gives pilots the sense that they are looking out the window regardless of the environmental conditions, and enables greater performance from TAWS and SVS.

For obstacles, existing SVS depictions of buildings today are simple stick figures or lines, whereas with Maxar the pilots will see an exact image of the windmill or cityscape. A true visual representation of the airport environment increases confidence in low visibility, and acts as a geospatially correct guide.

Vegetation and structures below 200 ft that are at least a half foot in diameter are also captured within the database, and there are more than 25 different classifications of vector data, giving OEMs and suppliers the flexibility to offer their customers varying levels of data, and prioritize essential flight info.

In addition to its new high-resolution terrain elevation database, Saab is developing a unique 3D high-resolution, image-based database and rendering engine. The SVS engines can support both head-up displays (HUDs) and full-color head-down displays, and can be integrated within the HUD computer or hosted on the aircraft avionics platform.

Another advantage of the photorealistic 3D terrain database is that the graphics processing can be implemented more easily to display the new SVS. The rendering engine will enable the first true 3D photorealistic SVS.

Certification of the new 3D image database will be qualified in accordance with EASA DAT 1 (European equivalent of FAA LOA 1) at data process assurance level (DPAL) 2, and is on pace for approval by the beginning of 2022.

The certified terrain and elevation data will provide global coverage at an accuracy of 3 meters, with a pixel resolution of 0.5 meter (~1.6 ft).

Implications for drone and eVTOL ops

So, where do the drone and UAM markets come into play, and how will these new aeronautical database capabilities affect these markets?

Today’s commercial drone market relies largely on remote pilots operating small UAS within visual line of sight while using static 2D ortho maps. The drone industry, at its foundation for airspace access, is managed with geospatial information.

Even for small UAS visual operations, both very high resolution and accuracy of the source maps can alter the safety and efficiency of not only the local flight but the industry as a whole. From a business operation perspective, map boundaries representing controlled airspace or a no-drone zone can determine if a major commercial site inspection is permitted or prohibited.

For the authorities, the accuracy of a drone TFR and geofencing boundaries affect safety, as drone operation may pose a risk to manned aircraft in the area. Precision geospatial data is needed to drive drone operations into daily life for everyone, but without modern map data and SVS, the utility in cities will be limited.

As the industry moves toward beyond visual line of sight (BVLOS) and autonomous operations, there will be more reliance on dynamic terrain, elevation, and obstacle information. When the drone moves beyond the pilot’s ability to maintain safe separations visually, they must rely on technology to provide see-and-avoid capability, especially during contingencies that require a return to home or loiter.

Detect-and-avoid – the term used for drones because there are no eyes in the aircraft – is being tackled by a number of technologies, including onboard sensors and automated traffic services.

But a key component that hasn’t garnered a lot of attention beyond preflight planning is a sophisticated and highly accurate terrain and obstacle database that can be used for 3D visualization, for conflict resolution maneuvers, and as a redundancy for GPS-denied navigation. NASA, through the UTM project and Urban Air Mobility Grand Challenge, has been working toward developing the foundation for autonomous BVLOS drones and UAM for several years.

Supplemental data service providers are considered a core component of the UAM traffic management system architecture, and a high priority is placed on accurate terrain and obstacle information. In a similar way to how current operator communications, navigation, and surveillance (CNS) systems provide for greater operational benefits, such as RNP, UTM will incorporate approvals for broad operating areas, known as “performance authorizations,” based on the technology and performance demonstrated by the drone operator.

With the focus being on “safe and efficient air traffic operations into, out of, and within a metropolitan area” by both manned and unmanned systems, SVS will be instrumental for future air taxi platforms to navigate in urban environments, take off and land in unconventional locations like building tops and vertiports, and perform a safe passenger transport mission.

Small, essential steps

As we continue to dream about the days of flying cars and autonomous air vehicle operations, it’s the small, incremental innovations that advance our current and near-future systems and services which will form the foundation for future urban flight.

NBAA President & CEO Ed Bolen captured this sentiment well at a recent NBAA regional conference where he addressed the crowd on the future outlook of business aviation. “This is the beginning of an exciting decade to come,” he remarks. “We’re talking about an era of innovation we have not seen before. It will help us do more and do better in the years to come.”


SeanSean Connor is director of unmanned systems at Discover Technology Intl. He is a sUAS pilot, policy analyst, and researcher specializing in the development of advanced avionics, drones, and urban air mobility.