Military Embedded Systems

Your flying taxi is here


June 14, 2019

Rick Hearn


The flying car: From The Jetsons to Blade Runner to Star Wars, the idea of escaping the traffic jam down on the ground and cruising through the sky has always seemed a promise too far out of reach to be real. Now, thanks to parallel advancements in battery technology and autonomous vehicles resulting from Tesla and other pioneering electric automobile manufacturers, we are rapidly approaching the era of the unmanned flying taxi.

Dozens of companies are seriously pursuing this emerging market – from Uber Elevate to Bell Air to Airbus A3. According to experts in the field, we are now at the stage where the biggest challenge is no longer technological but simply a matter of boosting public perception and confidence. The appeal of these futuristic conveyances is personal and tangible: Some estimate that 100 million people around the world have a daily commute that lasts 45 minutes. The champions of the new platforms claim that the benefits compared to existing rotorcraft are manifold, and include noise reduction, efficiency, zero operational emissions, and greater affordability.

The popular name for these vehicles is eVTOL, which stands for electric vertical take-off and landing. NASA uses the term “urban air mobility (UAM),” which it defines “as a safe and efficient system for air passenger and cargo transportation within an urban area, inclusive of small package delivery and other urban unmanned aerial system (UAS) services, that supports a mix of onboard/ground-piloted and increasingly autonomous operations.” Analysts predict major growth for the category. Booz Allen Hamilton, in its November 2018 “Urban Airborne Mobility Executive Report,” predicts that there will be 4,000 eVTOL aircraft in use within the next 10 years. Los Angeles is hoping that eVTOLs will be a viable way for visitors to the LA-hosted 2028 Olympics to zip from venue to venue.

The good news for commercial off-the-shelf (COTS) vendors is that the same size, weight, and power (SWaP)-optimized solutions they’ve been actively fielding in recent years to address various design assurance levels (DALs) of D0-254 safety-certifiable hardware requirements for manned and unmanned airborne platforms are also well-positioned to meet the needs of eVTOL vehicles. While safety certification specifications from the FAA [Federal Aviation Administration] and EASA [the EU Aviation Safety Agency] for traditional aircraft have long been defined and understood, eVTOL platforms bring with them a whole new set of concerns. To help the market get off the ground, EASA issued in October 2018 a document called “SPECIAL CONDITION for Vertical Take-Off and Landing (VTOL) Aircraft.”

EASA has developed – in the absence of certification specs for this type of craft – a complete set of dedicated technical specs in the form of a special condition for VTOL aircraft. This special condition addresses the unique characteristics of these products and prescribes airworthiness standards for the issuance of the type certificate, and changes to this type certificate, for a person-carrying VTOL aircraft in the small category, with lift/thrust units used to generate powered lift and control.

For onboard avionics systems, the EASA Special Condition document defines a different set of DAL levels from the familiar DAL A to DAL E used by safety-certifiable D0-254 hardware and DO-178C software. EASA calls these VTOL categories Function Development Assurance Levels (FDAL). FDALs are ranked by failure condition, from Minor to Catastrophic, on the basis of three categories of passenger. (Table 1.)

Figure 1 | VTOL categories known as “Function Development Assurance Levels” from EASA.



For COTS vendors, the eVTOL market holds great potential, since these platforms will require a number of subsystems that can be addressed early on with existing safety-certifiable COTS products. These autonomously piloted vehicles also will find use in military environments, as they can reduce the number of personnel at risk during flight while eliminating the significant noise of a helicopter’s rotating blades. The avionics requirements of these platforms provide a range of opportunities for system designers, including systems for flight control computer (FCC), automated mission management (AMM), detect and avoid (DAA), terrain awareness warning system (TAWS), CVR/FDR flight recorders, battery management, and propulsion.

COTS vendors already have reliable and proven MIL-class safety-certifiable solutions that UAM developers can use to start prototyping right away. So call Rosie the Robot and tell her to get your dinner ready. Your flying taxi will be bringing you home shortly.

Rick Hearn is the product manager for safety-certifiable solutions for Curtiss-Wright Defense Solutions.


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