Podcast: Unmanned Aerial Vehicles in Commercial Airspace

April 29, 2020 | BY: Paul Hart

Unmanned aerial vehicles (UAVs), also known as drones, are not exactly new to our skies. Commonly designed for defense applications, UAVs have been developed with significant military investment behind them. But emerging commercial markets for UAVs are adding new complexities to the aerospace industry and, given the rapid pace at which consumer technology evolves, safety protocols, standards, and regulations must adapt quickly.

Safety is inarguably the greatest challenge for getting UAVs to fly in civilian space. There’s the risk of accidents, such as dangerous crashes into the ground or buildings. This raises good questions about what capabilities can be safely integrated into an unmanned aircraft. Consider, for example, iterative route planning. Should an UAS be able to alter routes based on new information, or must UAVs always stick with the path specified at the outset?

There’s also the logistical challenge of ensuring unmanned aircraft aren’t interfering with other aircraft operators in commercial space, also known as unmanned traffic management (UTM). This, at its core, is a safety consideration as well.

In order to protect the lives of people both on the ground and in the air, as well as build the public’s confidence in emerging commercial UAV applications (such as drone delivery and air taxis), unmanned aircraft system (UAS) designers must comply with regulatory requirements on both the device level and air management level.

To dive deeper into the impact of commercial UAVs in civilian airspace, I joined Wind River’s Chief Strategy Officer on a recent podcast, now available for streaming.

Listen to the Unmanned Aerial Vehicles in Commercial Airspace podcast by Wind River.


John McHale
Hello - you're listening to the impact of unmanned systems from the battlefield to the consumer world. Hear how innovators use unmanned systems technology to drive top-line acceleration ROI. This is episode three of our podcast series, called Drones and Commercial Airspace - A Path to Safety. Podcast is sponsored by Wind River. For more information visit Today I'm joined by Paul Hart, CTO and Curtiss-Wright Fellow within the avionics business at Curtiss-Wright Defense Solutions and Gareth Noyes, CTO and Chief Strategy Officer for Wind River.

Could we start guys by each of you giving a brief description of your responsibilities with your different companies?
Paul Hart
Sure. So my name is Paul Hart. I'm the Chief Technology Officer and Technical Fellow of the avionics business of Curtiss-Wright and it's my job to look at new emerging technologies that we would, you know, introduce into our products to meet avionics and aerospace applications so that's my role.

Gareth Noyes
Great and I'm Gareth Noyes. My role at Wind River is Chief Strategy Officer and CTO side, look at all the forward-looking technologies and align that with the company strategy, look at where we're going to invest, which markets we're going to invest in and I have the privilege of working across all the markets we serve. Avionics and aerospace and defense is our largest market but I'm very involved in things like 5G in the telco business, transformation of industrial control systems and automotive and you know things like automative become very interesting as we start talking about unmanned systems because we see a blur going forward of those types of technology so I'm looking forward to talking about that.

John McHale
Thank you gentlemen - let's get started and turn to Paul first. What is the biggest challenge when it comes to providing safety certification for unmanned aircraft in the civilian space - is it a technology challenge or a bureaucratic hurdle to overcome?

Paul Hart
Well it's really both, but it's heavily loaded in terms of the technology. The challenges are obviously driven, well firstly by safety there are obviously significant risks of drones causing accidents, crashing into the ground, losing control, affecting other users of the air traffic system, other aircraft operators and the biggest challenge is making sure that drones are safe to fly so there are a lot of regulations for the small drones, you know, the recreational drones and the ones that fly below 400 feet and weigh less than 25 kilograms but for the larger drones that are actually sharing the air corridors in the airspace - they need to have systems to make sure that they are not going to infringe airspace and maintain the separations to the other users. So there's quite a number of technological challenges but there's also the confidence-building in the traveling public to make sure that, the traveling public are accepting of this technology and become users of it.

So for example, drone delivery services and things like that, they may become commonplace in a few years from now but of course people want to be sure that these are safe to fly and so those are the technology challenges as I see them there.

John McHale

Gareth Noyes
Yeah, no I think Paul is spot on there. I think it's a mix of both technology and regulatory challenges. Of course it's important to remember that unmanned aircraft are not new - the skies are filled with military unmanned aircraft and the way that they've been developed has been, you know, at a larger scale as really big systems with a lot of investment behind them. One of the things that's changing I think when we think about unmanned aircraft going forward is the pace of change of what I think of consumerization of technology.

So starting off with technologies that have been developed for consumer-type applications - toys and small aircraft that don't do a lot of damage on their own but of course as you increase the density of these things in the airspace, then managing them, making sure as the payload increases and so on that safety issues are addressed.

So I think it's that the fundamental change for me is that consumerization aspect, you know, the advances in small unmanned vehicles has really been advanced by miniaturization of technologies and mobile phone gyro sensors and things like that, making much more complex flight vehicles a possibility for even the hobbyist to develop. One of the challenges as we think about how these things that are flying in commercial airspace is how do we address risk at scale when these things become more complex both at the system level within the drones when they start being a higher risk because of the weight that they're carrying around and then the sheer density of how they're controlled in space.

For that was all there - the technology aspects but then from a regulation perspective I think we've had an infrastructure and commercial airspace that's been well-regulated by bodies like the FAA and there are good standards that have been adopted to how we develop software for those spaces as consumer-type applications start coming into the airspace as well, the overall approach to how you address certification and standards and so on really has to evolve as well so that's, I think as big a challenge as addressing that technology, which I agree with Paul, enormous on their own but it's another dimension that's going to be complex to address.

John McHale
Thanks and as I know both of you are aware even when certifying for manned aircraft in commercial worlds, when you go to different regions and countries there is not perfect harmonization. What about when it comes to unmanned aircraft - is there harmonization there? Is it as good as it is on manned flight or does more need to be discussed for safety certification?

Paul Hart
Yeah, if I can start off on that one, with where it is with drones for example, it's all very new to everyone so EASA and FAA, you know, in the last three, four years they've started to put a lot of effort into creating the rules and regulations of both certifying a drone and then operating it, so there are drone pilot licenses, there are certification standards for the drones themselves. Now there's generally the two types of drones - you have the ones that are recreational, kind of like toy drones that you buy as a birthday present for your nephew and he flies it in the back garden or takes it down the park and then there are the larger drones with cameras and payloads that would be potentially used by a law enforcement agency and that's when you're going into professional categories that require more levels of pilot training from the ground operator with the ground station controlling the drone sometimes while staying within line of sight but within line of sight you can be on the ground and the drone can go behind a building quite easily and what you do then if you lose visual contact or if you use lose datalink contact - that drone itself must have a redundant mode by which it can return to base, it has geofencing, it has algorithms that will allow it to return to a safe condition autonomously.

So there are a number of different approaches that the regulatory agencies are taking for that. Then you get the larger drones beyond that - the more tactical drones that weigh more than 55 pounds. Now the rules behind them are still really evolving but the general position is that they have to be certified to the same equivalent standard of a manned aircraft. So you get primarily the three different categories - part 23, 25, 27, 29. 23 and 25 are fixed-wing aircraft. 27, 29 are rotary wing aircraft and the difference between 23 and 25 is defined as weight and also altitude, operating altitude, and it's a similar thing for helicopters - 27 is small helicopters, 29 is large transport helicopters. Now if you are operating a drone that has an electro-optic turret on the aircraft that you know is the size of a light aircraft like a Cessna or a Piper aircraft - that would have to be certified under part 23 so all of the aerodynamics - things like stall speed, stall recovery, spin recovery, landing, takeoff, all of that needs to be addressed. Now, given that you don't have a pilot at the controls feeling all of the air loads and the whole dynamics, that has to be controlled within the aircraft itself by an autopilot. That autopilot will need to meet design assurance Level A so it has to guarantee better than one in ten to the minus nine less than probability of failure per flight hour.

So that is something that across the different regulatory agencies, as the regulation is falling in place, the general position is to certify to the same standards as the manned equivalent but on top of that you need certification of the ground control system, the telemetry control systems and the aircraft needs to have a detecting the void system as well so it has to have some means of determining any convergent flight paths with another aircraft and then computing an avoidance maneuver. Now that's quite well defined - it's in RTCA standards. They then will have to be implemented in software. So a lot of the regulatory agencies are generally harmonized but there are a lot of different deviations along the way and the rule-making is quite a complex picture.

But generally as you get to the larger drones the takeaway is they have to be certified to the same standards as a manned aircraft and then some with the data lengths of control and the detect and avoid systems. So that's generally the position.

John McHale
That was good, Paul. And Gareth, you know he mentioned control stations and I know Wind River was part of the common ground control station effort within the US military and of course that, as another, probably wrinkles everything because there's that compatible with everything else overseas.

Gareth Noyes
Right, exactly, now as Paul says I think there's a way to go before some of the regulation is harmonized. I think the commercial avionics supply chain has been fairly well established with Tier 178, ED-12C and so on and then there's generally a map in between these standards so there's commonality even though we have RTCA-type standards in the US and there are derivatives around the world that the ground base stations as well had another level of complexity to it, not just from a certification perspective but from a comms perspective as well. Now what compounds all of this is even though there are lots of standards out there, the FAA creates performance standards but they don't tell you how to implement them so there's a lot of gray area that the industry has to solve in terms of how you solve the Part 135 certification for example.

So it's fairly complex but what we do definitely see is that no matter how these standards end up mapping, there's a drive towards safety certification and if I think about it I think adjacency has become relevant here while we're talking about avionics and things being fairly well-designed, defined by things like RTCA. Autonomous vehicles for instance are really effectively unmanned because they happen not to be flying and they have other derivative standards like ISO 26262. So, you know, I think we need to understand best practice across multiple industries, note some of the complex problems going forward because we're not going to have the level of expertise that we see in very large, very well-established avionics companies and that expertise around certification and safety in particular isn't going to be prevalent in all the smaller companies doing smaller unmanned vehicles and so on.

So as an industry I see a real opportunity to help provide approaches that bring best-of-breed and safety pedigree that we've applied in commercial avionics and flowing that to other areas and one area we've seen that flow over is between the commercial and military standards - for instance in both Europe and the US so I think it's an evolving landscape. It certainly hasn't settled out yet but lots and lots of complexity to be untangled here.

John McHale
Thanks Gareth and I'm gonna come back to the issue with the next question which I think Paul sort of answered in a way. Do autonomous systems have fewer items that require safety certification or the opposite? After listening to what Paul said I'm not so sure that it's not more that they have, so what do you think?

Gareth Noyes
Well I think some of the technology assumptions are very, very different. You know, when I think about redundant systems in aircraft and really some of the design rules start with simplicity first and then build your way up into systems that are both robust and scalable and of course we've evolved to standards like the ARINC 653 that allows you to now partition multiple complex systems on a single based platform and that's the sort of work that Wind River and Curtiss-Wright do together. When I think about some of the unmanned vehicles that we see emerging, they're starting with a completely different point of view which is we'll take as many sensor inputs as we can, we'll start combining different types of sensors and technologies and so we're actually starting with a very complex baseline of technologies where we're trying to peel back from a safety perspective how all these things interoperate.

I think of avionics as really being, you know, grounds up safety first and add in capabilities where needed. A lot of the consumer-driven development that we see in unmanned vehicles is coming from the complete opposite side and so I think our goal and our opportunity is to merge these two viewpoints. I think it's unarguable that things like machine learning are going to have an impact both with unmanned vehicles but also with manned vehicles in the cockpit and applying these new types of technologies, forcing us to think about new approaches to safety and risk reduction is going to force us to address the problems slightly differently from the way that we've done in the past. And I think that's why this is such an interesting and dynamic environment because there's a lot of change that's been pushed on us by the emergence of all these technologies.

John McHale
Thanks Gareth. Paul, anything you want to add on that?

Paul Hart
I think that Gareth sums it up really. You know, it's a very complex set of situations you've got here - a lot of moving parts and it's going to be a while before everything settles down but there are technologies that are on our side - things like Gareth mentioned about the machine learning so there's a lot of it is by taking an unmanned aircraft - ie doesn't have a pilot there - all of the sensing and avoidance technology and just all of the controlling - all of that needs a whole set of sensors to do that, electro-optic, gyroscopic, radar-based sensors and not only these, you also have to look at common-mode failures. So two different sensing technologies, you want to have different failure modes and have a third system as an arbiter so there's a lot of other complexities of voting algorithms and to be sure that two common sensors don't fail in the same way. So there's a lot of technologies that you need to do and dissimilarities that you have to introduce to make sure the whole, as a system, it can meet the high safety requirements of the goal of meeting 10 to the minus 9 per flight hour.

That's quite a challenge and that's a very high bar to attain so it's good that the rules are set very high and it's our job to come up with the technical solutions that can achieve that, so I'd agree with Gareth just said there.

John McHale
Now I'll take you over to the military and I think I've asked you this question before Paul in the past. Currently the US military as many know is not required to abide by FAA safety certification specifications on unmanned systems. Military unmanned aircraft in the US, especially the larger ones like Global Hawk do need a manned escort when flying over national airspace though. Do you see safety certification becoming a requirement - I know they already use it because they're buying Wind River's for military aircraft but is it more becoming a requirement, Paul and I say that not just on the software side but on the on the hardware side and what Curtiss-Wright does?

Paul Hart
The United States Air Force is recognizing it - there's a standard called Mil Handbook 516C and it's one of the first mil standards that recognizes DO-178C for software and DO-254 for hardware and then the higher level system-level safety certification requirements in ARP-4754A and 4761 and so a lot of the RTCA and ARP standards, they're very much driven by the civilian world and to an extent, and I don't want to get controversial, but the a lot of the military side hasn't kept pace with things like multi-core processors and how would you certify a multi-core processor for a safety critical action application, to be sure that there's no interference between cores and you can run different criticality of software on the same processor without fear that a designer assurance level E is not going to have a divide by zero error that would cause a problem on a DAL-A partition.

So the figures, the civilian RTCA standards, they become quite mature and also the cost position papers - the military is now adopting or recognizing those standards for certification of these complex disciplines like a Global Hawk tied in a strategic UAV. So I would say yes, I would see that in time becoming a requirement because these aircraft still have to share the same air corridors as the traveling public flying in with the airlines. They have to maintain all of the vertical and lateral separations. They have to abide by all the air traffic control flight waypoint to waypoint and through-the-air corridors when transiting through controlled airspace.

It's very difficult to fly any intercontinental range even if your aircraft can fly above 60,000 feet you still have to descend through the airspace where which is quite congested in certain regions of the world so you still have to meet those rules of the road there. So I would say - do you see the military adopting the same levels of certification? Yeah, absolutely I'd say so.

John McHale
And Gareth, what about on the software side - are the requirements like that for DAL 178C or B?

Gareth Noyes
Yes now, I agree with what Paul said actually which is a lot of the innovation and forward thinking, for example multi-core safety certification that Wind River has been helping drive in the market, have been driven from the commercial side and I think when I ask myself why that is, I think it's simple - one is that we have a governmental agency that is seeking to protect civilians first and foremost. I mean air travel has become very, very safe as a result of that but the other is because the commercial environment, the liability around any failures is very high for commercial vendors and there isn't that same incentive on the military side.

That said, the military - we see an accelerating momentum towards adoption of civil standards and there's a couple of reasons. Paul mentioned your ability to operate your military aircraft across airspaces worldwide - showing conformance to something that is well recognized worldwide for commercial standards is a great way of getting there but of course the second reason why the military is looking to adopt more of the commercial type standard is really cost-driven because if you can drive commonality between military and commercial avionics, both on the software and hardware level, you can reduce overall costs, drive in a faster pace of innovation and so on.

And so, yes, I very much see that that blend between starting in the commercial and being adopted in the military and I think it's one of those things that as you see stabilization of standards and conformance between things that there's a rapid follow that we see amongst those two areas.

John McHale
I'm gonna come right back at you Gareth. Earlier in the broadcast you talked a little bit about sense and avoid technology and getting that right. Well has sense and avoid technology for unmanned aircraft become efficient enough to calm the fears of many human pilots? That's often what I hear.

Gareth Noyes
Yeah, I think there are a few things here. There's the - what's the reliability of sense and avoid technologies at the component level, at the system level within an unmanned aircraft or drone and then there's how confident are we about modes of operation where we have the experience to understand in a mode of operation where pilots for instance become comfortable that the technologies are mature enough. So I think we have to treat those two things separately because I think the technologies in the sensors themselves are becoming very, very mature and this is where we see again cross-pollination from other industries - a lot of innovation around sensor fusion and very complex high-bandwidth data streams in automotive. And the same approach is being applied in unmanned aircraft. So I think yes, they're becoming better but there's still of course work to do in terms of their operations and the trust that you have to build with actual people.

John McHale
Thanks. Paul, what are you seeing?

Paul Hart
Well yeah, I mean Gareth's point is people need to be comfortable with these things - these autonomous aircrafts have got to work out, detect and compute avoidance maneuvers if you're on a converging heading. So I think the technology is there but it hasn't been fielded widely enough for the traveling public to gain that confidence yet and it's like a driverless train. Now that you're starting to see them and they've been at theme parks for years and years and it becomes habitual and I think it's like a lot of things that in years to come we will see that the technology did work, it was reliable and what was the problem about it. But I think in terms of the sense of detect and avoid technology there are published standards that determine all of the different convergence geometries. Now all of those use cases haven't really been evaluated because not enough systems have been fielded yet but in time those different avoidance maneuvers will unfortunately be exercised and we trust they would work correctly when the time comes and then start building up that track record. So it still has got a distance to run before the trust is there but it's off to a good start.

John McHale
Yes, you have to convince people that they can still get on a plane that's flying itself even without a grey-haired pilot up there and we've kind of touched on this a little bit we talked a little bit about the differences between certifying unmanned aircraft versus manned aircraft, certification harmonization between two different countries and different regions but you've both written articles on this for certifying COTS hardware and software into LA for manned aircraft so what are the next challenges for certifying COTS hardware for unmanned aircraft, Paul and then I'll ask the software one of you, Gareth.

Paul Hart
On the hardware we're seeing now things like firstly, the hardware, the electronics that every hardware vendor - the challenges they have is that no longer does the electronics components industry produce microprocessors and memory devices that are designed for military or defense aerospace applications so we have to take our components from the same pool as iPods and, you know tablet PCs, and servers and televisions for example and they have very short design lives - three to five years - so one of the challenges is having a technology that has some longevity to it and can be an open system so every five/seven/nine years you can do a technology refresh  and be able to port DAL-A software for example onto new hardware as and when that becomes available. But also the other thing is the semiconductor geometries are getting so small - they've been sub 15 nanometer for some time now and so they are susceptible to single event upsets - things like sunspot activity generating neutrinos that interact with air molecules and can cause what's called a bit flip so that the low-level machine code micro code and the nought can become a one, a one can become a zero and at the very low levels they are not detectable so you have to have other systems in parallel or lockstep processes and doing a check for every line of code execution in case a single event effect happens.

And so that's the only way you can detect these things so as you go to high altitude or if you use more and more small geometry set technology that's really designed for the consumer market that is a challenge when you have to demonstrate that you can mitigate all of those risks that didn't exist a few years ago when the technologies, when the geometries were larger and I'll just say another thing - the FAA they in one of their published TSOs in terms of the design assurance levels for a UAV, they are actually a layer more severe. A lot of the safety criticality is based on the kinetic energy of the aircraft, so the half MV squared, so I'm a large mass air vehicle traveling high-velocity velocity-squared - that could do a lot of impact damage and so the terminal velocity and the mass are very big drivers behind the design assurance levels that you have to design the systems within the UAV, so the detect and avoid, the flight control computer, the terrain awareness warning system and just basically the engine controls, FADECs, that type of thing.

So for UAVs they are a level more critical, they move up the design assurance level scale as you go to the heavier and faster velocity UAVs so that is a challenge that you have on the platform.

John McHale
Gareth, on the software side what do you see?

Gareth Noyes
Yeah, well I think we take the challenges that the Poland team deal with on the hardware side and then we have to apply our software know-how to make that work in the system and as Paul says, in the past what we saw was a fairly reliable slow-paced roadmap from the silicon vendors around you know avionics or multi-grade hardware that were in a simple single core element that really didn't have much complexity relatively speaking from a safety perspective. Well of course that's now changing as Paul said. There's more consumer-grade because of challenges with delivery of Moore's law, things have become multi-core and this is where Wind River has put the investment - in figuring out what is that transition to a more complex software system where the underlying hardware system is also complex.

And we've really done that through abstraction virtualization and it's ironic that in control systems some of the first systems to be virtualized were actually avionics systems with IMA architecture and so that really led a whole evolution of how we address these things and Wind River has been driving that for a while. Now I do think there's a flipside of this move towards consumerization which is in the past there was never sufficient volume in the avionics market to drive a semiconductor ecosystem to do something specific from a safety perspective for those designs. Well I think with the advent of autonomous systems, in particular autonomous driving, there's the prospect of having much higher-volume safety systems and we're starting to see silicon vendors for instance start to come out with the roadmaps where they have dual cause safety islands with lockstep - things like that but actually safety features built into the silicon micro architecture and as opposed to us having to retrofit some safeguards around that in the past so that's a mixed blessing.

As Paul says there's a change from military grade to consumer but with that comes some benefits. Now I think the thing that we have to recognize is that we have to adapt to build in safe systems that are changing more rapidly over time. Our approach to safety certification in the past has been to lock down a design, freeze all the software and hardware components and go through our processes for software assurance and requirements traceability through to test and that's something that's very, very costly and can take a lot of time. We need to rethink the way that we're doing safety so that we can think about how not only we adapt to these much more complex underlying hardware systems but how we adapt affordability and much faster time scale.

So I think this is a an opportunity for us as an industry to rethink how we've been tackling safety, building on the 40-plus years of heritage that companies like Wind River and Curtiss-Wright have built in doing this for avionics systems in the commercial space.

John McHale
Thanks guys and as we wrap up here I'm going to ask you to predict the future. I'm gonna start with you Paul. Where do you see certification of unmanned systems 5-10 years from now - a solved problem or will the government be playing catch-up?

Paul Hart
I think we're always going to be in catch-up so the government bodies, the regulations will lag a little bit behind technology, I feel. But, you know, five, ten years from now we'll be seeing drones that will be delivering medicines to remote areas of the world and providing real benefits to people and I think the certification for that - we'll be looking at machine learning certification, artificial intelligence, a lot of machine learning algorithms and how do you certify those? So as the technology evolves that will need regulatory measures behind it but I think the future looks good and the regulatory agencies are going to keep pace with the technology to make sure it stays safe so that's how I see the future.

John McHale
Gareth, where you putting your money?

Gareth Noyes
First of all, I know we've introduced a lot of complexity and concern throughout this discussion but I think we should remember we know how to build safe systems today. I think that the issue is how do we build more complex, evolving safe systems but I agree with Paul. I think the future is very bright for unmanned systems. We're seeing a lot of design stats for unmanned vehicles. There's talk of personal client taxis and you've read about things like Uber Elevate and things like that. There's investment going on now which is good and really pushing the evolution of how we view unmanned systems. The proof is going to be in the consumer acceptance and I think at some point in the next decade it is going to be fairly common practice to see unmanned vehicles do local delivery. At some point in my lifetime I expect to see things like flying taxis as well so I'm quite bullish on the future. There's a lot of work to be done but that's exactly what we're investing in so we're very excited about that

John McHale
So thanks for speaking today gentlemen. It was an excellent conversation. If you want to learn more about Curtiss-Wright Defense Solutions please visit The podcast series is sponsored by Wind River. For more information visit Our next episode will be technological capabilities for autonomous flight. Thank you.

Paul Hart

Author’s Biography

Paul Hart

Chief Technology Officer

Paul Hart joined Curtiss-Wright in 1982 as a graduate engineer and has worked for 18 years in the flight recorder business. Paul also worked for Thales for 2.5 years in helicopter flight management and was responsible for the mission systems group at Cobham Aviation Services for 7 years. In 2011 Paul re-joined Curtiss-Wright as the Director of Avionics Engineering and transitioned to the Avionics CTO.

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