Webinar on 'Remote inspection: Part 1 - Drones for remote inspection'

Remote inspection: Part 1 - Drones for remote inspection 

Speakers: Paul Bryan, David Andrews, Elizabeth Stephens and Leon Walsh 

Paul [00:00] Thank you very much, Alice, and good afternoon to everybody, wherever you are in the world. It's good that we have a number of international people here. Welcome to the first in the Technical Tuesdays webinar series for 2021. As you'll see, this is the first of what's actually three parts. We're going to be talking about drones for remote inspection, and I've got to [indistinct] a number of colleagues to actually help me this afternoon. 

I'm sure all of you will have seen this website because you've probably registered via it, but just to sort of remind you that this is the first in three. In February we're going to be having a webinar which is talking about the use of laser scanning. It's a remote inspection tool, and then in March, we'll be talking about how, well, we call it reality capture, but it's basically the combination of laser scanning and photogrammetry. And that can be used alongside imagery captured from drones, for instance, to help the remote inspection of historic buildings and structures. I will highlight the other webinars that are in the series there. You'll see there's a number of them there, and there may be a few more to be added to it, so please come back and follow these webinars. 

Before I actually kick off on the actual presentation, just to highlight that I work within Technical Conservation team, and it's very active in generating guidance and research related to all aspects of technical conservation applied to heritage. This is the latest guidance booklet, which you can download for free. You can see it was released in November last year, and it has a fantastic picture of the Iron Bridge on there. It's not on fire. That's the new lighting scheme that's been actually fitted around the bridge, so please take a note to have a look at this. Download the guidance booklet. You'll see all of the geospatial survey guidance as well as a whole range of technical conservation work. 

Anyway, that's the introduction. We're here to sort of talk about drones, specifically for their remote inspection application. There's my contact details. I'm the geospatial manager within Technical Conservation team within Historic England. There's my contact details there, and I think Matt will be providing the contact details for all of the four speakers at the end of the webinar. I'd highlight ARPAS UK, GEO Business, well, hopefully GEO Business 2021 later this year, and the Survey Association, that we work very closely with, and I will be mentioning a couple of them during my talk. 

So, just an outline on the actual webinar that we're going to be talking about. I'm kicking the webinar off already, and I'll just give a little bit of sort of background, introductory background, to the use of drones within heritage in-- how our use of them has developed to where we are currently. I'll then hand over to my colleague David Andrews, who will guide you through the regulations that underpin the safe use of drones in the UK, particularly the new European regulations that started at the beginning of this year. Some of you may be aware of them already. Some of you may not have heard of these already, but they are very important for the safe use of drones around the world. 

My colleague Elizabeth Stephens, or Lizzie as we call here, will be then talking about the essential pre-planning because you can't really just take your drone, go out to site and just get on with it. There are certain sort of processes and protocols you have to follow, and so Lizzie will take you through that. And then we'll have Lee on, talking about his use of drones within his conservation engineering area, and particularly how his team are already using them for structural inspection work. 

As I say, I manage the geospatial survey team, which is usually based in the Tanner Row office in York, but unfortunately, like most of the offices in Historic England and probably around the country, they're currently closed due to the current pandemic. But as you can see, we specialise in geospatial survey techniques applied to heritage. 

What does the actual team do? Well, we're involved-- well, we are actually a practising team. We're quite small. There's only five of us who would usually be out and about sort of surveying at sites, but of course, Covid has curtailed that for now. But we're involved in a variety of initiatives. For instance, the Heritage at Risk initiative, HAR as we call it, Heritage Action Zones and a variety of other research projects that Historic England undertake. 

We also work with English Heritage. Up until 2015, we were all English Heritage until English Heritage effectively split in two and Historic England was created. So we continued working with English Heritage through what's called a shared service agreement. We're also involved in collaborative research, and if any of you can actually read the details on that image, you can see it's quite sort of a detailed piece of work, looking at what lies beneath the lichens on Stonehenge, which is slightly different to what we're talking about today. That's very detailed inspection. So that gives you a flavour to the sort of collaborative research that we're undertaking and we're keen to actually keep doing in the future. And then, we undertake training and produce technical guidance related to geospatial survey techniques. A couple of them you can see there. 

So, as a bit of an ice breaker, we'll start off with a poll, and can I ask my colleague Alice to bring the poll in? You can see there, we're asking a number of questions. That you, Alice. I can actually see them all. Please click away which one applies to you, but what we're looking at is, how many of you already fly drones in-house? In other words, you either fly them yourself or you have people within your team/department that do that. 

Point two is, do you not do in-house work, and do you commission from external contractors? If you don't do either of those two, are you looking to use drones at some point in the future. Or finally, as my wife keeps reminding me, not everyone's interested in drones as much as maybe we are. But within the heritage application, are you keen to know more about this? Because we have a number of plans for guidance in the near future, so I'll let that sort of settle down. It appears that the people that are looking to use drones in the future is coming out top. We have quite a sort of close... not shift. What's the word? I can't think of it. 

So we've got quite a sort of number of people across all four, which is good, so we've got a number of people that probably know a lot about flying drones, a lot of people that know about what to ask for when you commission it, and a lot of people that are maybe interested in using them, so hopefully this webinar will help you out. So I think we can end that poll now. Thank you very much, Alice. 

And if I skip onto the next one. Thank you. Right, these days, I'm using the term 'drone', but when they first sort of arrived in our area, there were various acronyms that came out, but a drone these days can be one of those, an unpiloted aircraft or spacecraft. It could be an aircraft without a human pilot on board. It can be an unmanned aircraft that can fly autonomously, i.e. on its own, or it can be a flying robot that can be remote controlled. You'll see we've got some of the military applications highlighted there. 

But these days, we normally refer to them as remotely piloted aircraft systems, or ARPAS, and I think that's the term, other than the word drones, that is used across, certainly the UK, and across Europe. And here I'll highlight the UK Drone Association, which is ARPAS UK, and they're the body that I would highly recommend you sort of have a look at their website, maybe think about joining, because they're the people to go to if you have any sort of queries/questions regarding the commercial aspect of using drones, or the professional use of drones. 

They're active themselves, generating sort of-- Well, normally they'd be speaking at conferences, things like that, so please have a look at what they have to offer. In our area-- There's me, unfortunately, holding a drone. What is the drone in our area? Well, it's simply a platform for carry something. In our area, that's normally, like, a sensor. We refer to sensors, or that can be a camera, a laser scanner, a LiDAR scanner, thermal camera, multispectral hyperspectral imaging camera – they're mainly used in the agricultural application of drones. Or what we're actually seeing is a combination of some of these, and some of the later strands can now fly two, if not three, of these sensors simultaneously, so for our area, this is really sort of exciting news, and so it's not just fly once, record once. It's fly once and record many, many times, which is really useful. 

However, in terms of the types of drones, we certainly have only come across two so far. You've got the fixed-wing and the rotary. The fixed-wing are not really used for consumer and leisure application. I don't think I've seen many of them sort of flown, when I've been out, sort of travelling. They're mainly used for sort of commercial purposes, but the rotary one is the one that seems to be used across all of those applications. 

So if we have a quick look at this, the fixed-wing, I'll highlight-- These are the images taken from the guidance that the TSA, or the Survey Association, generated, which you can download for free from their website. Fixed-wing, it has a number of advantages. The shape, delta wing, effectively, a bit like the paper planes that some of us may have made when we were younger, or maybe even older. Very lightweight construction – polystyrene, carbon fibre, that sort of thing – so when they're up in the air, they can actually fly for quite a long time. 

They're designed for actually sort of going at some speed. Whether or not you need a 90mph fixed-wing drone for remote inspection is another thing. And they can glide over longer distances, but here you have to be aware of the regulations, and I think it's going to be some time before these fixed-wing drones can fly way beyond visual line of sight by everyone. 

So within our area, they tend to be used for sort of mapping purposes. They're great for sort of doing linear runs of overlapping images. The downside is, of course, their inability to hover. For inspection, that's not particularly good, as soon as they come to a stop in the air, unfortunately, gravity takes over. In the past, we've seen more automated image capture and exposure control, which effectively has limited the quality of the imagery. That has been improved substantially by the manufacturers in recent years, so I think the quality of the imaging from a fixed-wing is a lot better than it used to be. 

If we look at rotary, you can see why I'm sort of doing this, if you think about sort of inspection work. Rotary tends to have – well, there's a clue in the title – they tend to have multiple rotors. Between 4 and 12 is typically used. They have good manoeuvrability in the air. They have a slower speed; 40mph is still a considerable speed for a drone to fly. And of course, the obvious one is that they can hover, so when you're actually looking at a piece of stonework on the front of Saint Mary's Church, Dudley Royal, for instance, that's an important sort of factor. The more rotors, or the more lift, that they can generate, then the heavier the payload and carry. 

So as I said earlier, we are starting to see multiple sensors being carried, but the only downside with that is that the heavier the payload, the shorter the battery life. So most drone pilots these days come equipped to site with multiple batteries and battery chargers, and even though I say up to 30 minutes is a sort of normal time, some of the later drones, we start to see 40/45 minutes battery life, so there's an awful lot you can do within that time scale. However, once the battery sort of drops, you have to come down and change it and go off again. 

So in terms of inspection, monitoring, survey, they are very, very good indeed, very applicable and also good for presentational aspects on heritage buildings and structures. The downside to them is they are heavier, particularly with multiple sensors on there, so there is a risk. And I think, as David will point out when he talks about regulations, risk has become a lot more important when applying the regulations. I've said shorter flight speed. Sorry, slower speed and shorter flight time, not speed. That's what my slide says. 

So just looking back at drones, they're not new. Yeah, sometimes it feels like they've just appeared on the shelves in the past couple of years. The earlier versions date back to the 1850s, but they were predominantly a sort of flying torpedo. So here we have an image of the Kettering Book, which is the one on the left, which was quite sophisticated for its time. It had some sort of gyro system on board so it could vaguely go in the right direction, but World War II was a major driver of drone technology. The V1, V2 bombers, I think, fall into this category. So the main application of drones, as I say, were military.  

In terms of commercial and consumer developments, things seem to have taken off. Apologies, everyone. Apologies, Gary in my team for saying that! This is often referred to as the golden age for drones because since 2010, all manner of sort of potential applications have been developed, and here we see Amazon Air, which is the drone delivery service that they're still working on, but I think there are examples of drones being used already to deliver, particularly, medical supplies – up in Scotland, for instance, from the mainland to one of the Scottish islands. Very important work that it's doing, and it could be that these things will become more familiar in the near future. 

In terms of our work, I go back to 2008, which is when we first encountered a drone. This is during a demonstration of Fountains Abbey, which is the World Heritage site in North Yorkshire, and it was a demonstration by Microdrones. Microdrones are still a manufacturer that are generating drones, and what you see on the slide there is not dissimilar to what we're using today. However, the technology that has gone into it, the stabilisation, for instance, of the camera is not so much like a pendulum that's hanging below the drone as it was in this particular one. Yes, it took footage, but it was a little bit shaky, but it's all the ancillary equipment that came with the drone that you see on the right there. But these days drones are becoming smaller and smaller, and the actual controllers are basically mobile phone size as well. 

So skipping forward, since that first encounter with a drone, it was obvious that drones had a place within heritage to sort of give you a view of a subject that was quite hard to by any other sort of means. So Historic England, after it was created in 2015, have been building up its knowledge of drones, and in the last couple of years, we've invested in the hardware. You can see a number of the drones that we now are using and looking to use, such as the Elios 2 in the bottom right, but also investing in the people. So there you've got the original five of the Historic England drone team. Lizzie is the one on the right, who will be talking later. And we've now got nine qualified drone pilots across the organisation and two more waiting to take their new course. And as I'll say later on, these are not just being used for remote inspection, but they are being used for a wide variety of heritage applications. Sorry, I'm about to say that now. Apologies for that. I thought I was talking about it later on. 

So before I hand over to David to talk about the regulations, just a sort of snapshot of, are drones useful for heritage? I personally think yes. That's a big yes as well, and we've got experience to back that up. For me, they're an eye in the sky for capturing unique views of heritage structures, such as the Dunston Staiths in the top there, which is a fantastic timber structure on the River Tyne up near Gateshead in Newcastle, and then you've got the World Heritage site of Fountains Abbey in the bottom there. Yes, you could capture them from fixed-wing aircraft, but drones enabled you to fly a lot lower and a lot nearer the object.  

However, as well as getting those sort of wider shots, they are very, very good for getting these, and this is where we're sort of getting into the inspection applications. Leon will particularly talk about this towards the end. And there you see you've got one image of many that Lizzie took during her drone surveys at Saint Mary's Church, which is focused on one particular piece of detail. But as we'll say in our third webinar, the imagery from this is also useful within modern survey technology, for instance – structural motion photogrammetry. 

So such images have multiple purposes. So it's like image once, use many times, and yes, there are regulations to consider, but they enable you to sort of do detailed surveys of individual statues or in the case of the bottom image, which is from a [wall-top?] survey that English Heritage asked us to commission for Lincoln Bishops' Palace, which is just south of Lincoln Cathedral in Lincoln. And the imagery from that, yes, it provided English Heritage with some very detailed information on the tops of the walls, which are quite difficult to get to by other means, but that imagery was also used in the 3D geospatial survey that we'll talk about in the third webinar in March. 

Drones also have a part to play within archaeological survey. They're not the only tool. They're a complimentary tool, and for instance, in this example that Gary, Gary Young-- Gary Young is the chief drone pilot for Historic England. He couldn't present this afternoon, but he undertook this survey, and he probably undertook longer driving to the site in Lincolnshire than it took to actually undertake the survey itself. But even within about 20 minutes on site, very detailed information can be teased out of the photography and the post-processing to compliment the ground-based analysis and also sort of off-site analysis that colleagues in Historic England archaeological teams regularly are involved in. 

If we actually think about heritage that is not easy to see. For instance, it might be hidden away. It might be in a well, as we see in the top image there. This is one of the wells at Lincoln Bishops' Palace. Not safe to actually send anyone down, maybe sort of confined space, but drone is an ideal tool to send down there to remotely capture the space. This is where the likes of the Elios 2, which we're just about to acquire later this month, it can be applied for doing surveys of wells, chimneys, internal spaces, but spaces that are maybe difficult or maybe out of bounds for a person. So if you can send a remote system in that will capture enough imagery and light it – that's a crucial part of the Elios 2 system, the actual 360-degree lighting – then that give you a sort of an eye in the sky, so to speak, within difficult-to-access spaces. So another additional aspect for remote inspection.  

And then if we go back to our colleagues in English Heritage may know, or may not know, that they actually fly drones as well. Their lead pilot there is Jamie Ballinger, who works in the marketing team, and like us, he's probably curtailed in terms of flying, but his work is highlighted within their YouTube 'Postcard from' series, and if you've got a free moment, I'd highly recommend you looking at that, because even though it's mainly aimed at sort of presented science to the public from a sort of touristy application, it's still a means of sort of visually inspecting the structures and the landscape, indeed, the landscape around it as well. 

However, drones can also be-- well, I've used the word 'unauthorised menace' there, and I'm sure we've all encountered or maybe seen drones being used in ways that maybe you've taken a sharp intake of breath and thought, hmm, I wouldn't be doing that, or should I go over and say, 'Maybe you should be doing something else'? They can, and they do, form a danger to the public within a heritage historic building structure, site or landscape. 

And the image you see on screen, it's just a frame from a YouTube video that was uploaded to YouTube by someone without English Heritage permission. This is an English Heritage site, but when you looked at the video, it was obvious that the person flying it had contravened the regulations on a number of counts. However, they'd flown it. They'd uploaded the imagery, so there was not a lot that could be done other than use it as an example of the dangers, I suppose, of flying drones. 

So on that note, I think I'll pass over to my colleague David, who will hopefully take you through the regulations that are there to underpin the safe flying of drones in the UK. So can I hand over to you, David? 

David [26:16] Yes, thank you, Paul, and good afternoon to everyone. So I'm going to spend the next few minutes, as Paul says, talking about regulations and how they've changed since last year. So a bit of a facetious question here: 'I got a drone for Christmas. Can I use it for remote inspection?' There's a short answer, then a long answer, which is going to be basically what my talk is about. If it weighs less than 250 grams, then it is likely that you could use it, but there are still some caveats. 

For a start you'd need to get an operator ID, which I'll talk about in a minute, and although you don't need a flyer ID if it's under 250 grams, it's worth doing that training that's required to get one. There's the link for registering your drone and getting an operator ID, but if you want to do anything that's going to involve flying near other people, flying near anything that's not under your control, then you are going to need further training and registration and insurance. 

So here's the flyer from the CAA telling you that you need to register your drone to get an operator ID. As it says there, it's £9 a year, and what you do need to do is when you get the number, print it out on a sticky label and actually stick it to the drone, and the idea is that if, for example, you were to crash the drone into someone's land, it could be retrieved and traced back to you. So that's a good incentive to do things correctly and to follow the law there. 

So before we get into the nitty-gritty, here's another poll that Alice is going to bring up, and judging by the responses to Paul's poll, I think we're going to have quite a few correct answers, but we'll let it run and see what happens. 

So yeah, the two possible right answers are pulling ahead there. The definitive right answer is option C, 400 feet, because aviation tends to use feet for measuring height. One hundred and twenty-two metres is approximately 400 feet. For those of you who put 500 feet, you might be thinking about how low manned aviation can fly, and that's why drones are only meant to fly up to 400 feet, to have maintained that 100-feet separation between drones and manned aviation, although it's obviously worth bearing in mind that planes can be a lot lower when they're coming into land, and military aircraft doing low-flying exercises could be a lot lower as well. Helicopters could potentially be down to 10 feet, so that's another reason for all the training [indistinct] that's required. 

The 500 metres there, if it was familiar to somebody, is because that's what the CAA deems as the maximum distance that you can potentially see your drone. In practice, depending on the size of the drone and the atmospheric conditions, it could be a lot less than that, but as I'll go on to talk about, the term 'visual line of sight', the maximum distance for visual line of sight is deemed to be 500 metres. 

So we'll move on to the next slide. So just to recap what was happening before 1st January this year, there was obviously still already measures in place to ensure that drones were operated in a safe manner, but there was this distinction between drones being used for actual work and drones being used for leisure, and to be able to use your drone for work, you had to have, as per this list, the flyer ID, the operator ID that I mentioned before, pass a theory test and then a flight test to obtain a suitable qualification, have an operations manual that would be approved by the CAA, and all those [along with?] insurance would allow you to get what used to be called a Permission for Commercial Operations, PfCO for short, and this would allow you to fly your drone in a congested area and also fly it within fifty metres of people, structures, vessels, vehicles not under your control. 

So what do we mean by a congested area? It's basically a built-up area mainly used for commercial or residential purposes but also includes these days recreational areas or parks, areas where large numbers of people are likely to gather. If you hadn't got a Permission for Commercial Operations, not only would you not have been able to do work for any kind of remuneration, you wouldn't be able to fly within 150 metres of people in congested areas. That's people not under your control. There's a lot of PfCOs still out there, obviously, seeing as we're only in the early days of January, and operators with that permission will be able to continue working under that auspice until 31st December 2023. 

Moving onto the next slide. Have the drone regulations changed? I think I've sort of already said yes, they have. Paul probably mentioned it as well. Yes, on 31st December, there was a switch over to new EU-wide regulations that are, or were, developed by the European Union Aviation Safety Agency, and as I think I've already mentioned, the regulations adopted a risk-based approach, and for that reason, they don't distinguish between whether you're flying for leisure or commercial purposes.  

And within these new regulations, there's basically three levels of competency that could be required. The basic competency test is the same test I was talking about earlier that you need to take to get your flyer ID. It used to be 20 questions. It's not 40 questions. I haven't seen if the questions differ widely or whether it's just more on the same sort of subjects. 

One less rigorous qualification that you can obtain is the Certificate of Competency for flying in Subcategory A2 of the open category, which I will go on to talk about in a minute and will become clearer, and then there's the, what is now called, the VLOS certificate, or Visual Line of Sight certificate, which is further abbreviated to GVC, and that is basically what is going to-- or has replaced, the PfCO qualification route. 

So here's just a sort of graphic trying to explain the new categories. So the Open category down there in the bottom, which is further subdivided into A1, A2 and A3. Then there's Specific category, which is more or less what you'd have been flying with a PfCO. Then the Certified category, which is more rigorous and is designed for potentially allowing things like the drone parcel delivery proposals that Paul showed us earlier. 

So just to break things up a bit more, we've got another question, and I'll let people answer that. Right, so I'm glad to see that things are sort of bottoming out as answer D, 'It depends', because I've sort of touched on already and hopefully going on to explain that it all depends on qualification and the situation. So for those who said 150 metres, that would be true if you had no particular permissions and no control over the building, or you were flying in a congested area. Answer B would be the case if you had some kind of permissions but the building wasn't under your control. If the building's under your control, then you could potentially fly as close to it as you wanted, but I've put 'as is safe' because there's still an obligation to fly in a safe manner. 

So yes, I'm glad to see that most people said D. This is probably now a good time to talk about what 'under your control' means. Basically, if you've been asked to use your drone to remotely inspect a building by the building owner and there's no one else around, then you can definitely say the building's under your control. If there's people around but they've been suitably briefed and can be relied upon to follow your brief, so for example, if it was an occupied building and everyone could be relied upon to stay indoors for the duration of the flight, then that again would be under your control, but if it was something like a sports stadium where there was an event going on or a shopping centre where there's-- you could argue perhaps that the people have paid to come in, so potentially under your control, but you aren't even going to be in a position to properly brief them, so they technically wouldn't be under your control. 

So now I'm going to move on to the next slide, and if Alice can remove the poll. So just going to start talking about these new categories, so the first one there, 'Open category', that's subdivided into those three subcategories. And basically, the Open category presents little or no risk to third parties, as long as operations are conducted in accordance with basic and predefined characteristics. We're not subject to further authorisation requirements. The graphic's a bit small, but for the first one, you can basically see that the person's flying a suitable distance away from any buildings or whatever, and the little badge down at the bottom there is indicating that they're probably flying a drone that weighs less than 250 grams but technically has a classification from the EU, which I'll go onto in a minute. 

The Subcategory A2 is potentially a bit more dangerous, and this is where you can take the Certificate of Competency that I mentioned earlier. That involves passing a theory test and then some self-certified flying practice. So if you were to achieve that and get the Certificate of Competency – excuse my teeth – then you'd be able to fly closer to people, potentially a lot closer in a low-speed mode that maybe a drone hasn't got at the moment but potentially could have. Then you've got Subcategory A3 there as well, where you're far away from people and buildings, so that big pile of labels down at the bottom there suggests that most drones could be flown in that area in those circumstances. 

So this is just to confirm that to be in the open category, the flights must be visual line of sight, as in all cases not above 400 feet and a maximum take-off mass of less than 25 kilograms, but obviously, in some of those categories, it's an order of magnitude less than 25 kilograms. There's the summary of those three subcategories of the Open category. 

Right, so moving on to the specific category. So this is a greater risk than the open category, or perhaps just one or more elements of the operation fall outside the remit of the Open category. To work in this area or just to fly a drone in this area, then you would need an operational authorisation from the CAA, which would be based on a safety risk assessment, but also require the GVC that I mentioned earlier. 

Yeah, so there we are. As well as the GVC, you'd also need the operations manuals before, and it's all very similar to the previous permission for the commercial operation route. As it says there, the GVC will have a validity of five years, after which you'd have to retake the course. The certified category is operations that present an equivalent risk to that of manned aviation and for that reason is subject to the same regulatory regime. So you can see that it's basically larger aircraft potentially flying higher than 400 feet. 

Now, just going back to the classification that I mentioned earlier, so here's the list of the different classifications, and these are going to be based on mainly the weight of the drone but also the potential speed, so it's all to do with kinetic energy, so going back to the safety aspect, how much damage could be done by the drone? So potentially a very lightweight drone flying very slowly could maybe hit a person without actually severely injuring them, although that's obviously something you'd want to avoid in all cases. 

At the moment, there's no drones on the market that have these EU markings, the badges there for class 0 through to 4, but if you go on the CAA website, you'll see how in the interim, they're categorising existing drones to fit into those classes, and as I said before, it's to do with weight mostly. The actual use of the marks isn't actually going to be mandatory until 1st January 2023, so anyone who's got a drone now needn't worry about those for the time being, or anyone who's thinking of buying a drone in the near future. 

And moving on to my summary there. So there's the three categories, and that link there to the CAA fact sheet, 'Using a Drone for Work' gives a very good summary of those categories. As we said before, the Open category is intended for low-risk drone flights, for example, because you're flying a very light drone or in an open area. It's divided into these three subcategories, so A1 for drones less than 250 grams, which you could fly over people for a short period of time but not over a crowd. A2, you must keep some distance from people, normally 30 metres. This depends, among other things, on the drone you're flying, so going back to the weight. And to fly in Subcategory A2, as well as passing a normal flyer ID test, you'd need to pass this Certificate of Competency.  

In A3, you need to be at least 50 metres horizontally away from people and 150 metres away from parks and other industrial and other built-up areas. The Specific category is operations that present a great risk than the open category, and it's pretty much similar to the previous PfCO process. And then certified categories for large, unmanned aircraft, for example, transporting parcels over the city and are subject to higher levels of approval and regulation. 

So just to reiterate, I would highly recommend going on the CAA website. If you haven't got the time to read all the different documents they've got, a good start is this fact sheet that I've given you the link to there. So now I think I pass on to Lizzie, who's going to talk about more detailed summary-- 

Paul [46:17] Thank you, David, yeah. Before Lizzie speaks, can I just highlight it's quarter to two. I think we're going to be looking at overrunning beyond the hour, so I hope most of your will be able to stay with us. Apologies if some of you actually have to leave early. But we can now hand over to Lizzie. Sorry, I'll shut up now, David, and you can hand over to Lizzie. 

David [46:45] OK, great. So yeah, sorry if I droned on and sorry to Gary for that one. I'm going to pass over to Lizzie, who's going to talk about the potential pre-planning that's required before we undertake a remote flight. 

Lizzie [47:01] Hi. Thank you, David. So I'm going to be talking through the planning involved in a drone flight. So for our work, we prepare a pre-site assessment for every flight, which is normally carried out remotely, depending on the different distance from the site we're going to be working at. To prepare this pre-site assessment using a large variety of websites and paper maps and different things, there's a lot of resources available, and I'd say it's good to not rely on just one source. Check with different sources to make sure everything is corresponding and nothing's been missed on a particular source. 

Google Maps is a good starting point, as well as the Drone Safe app and the web-based version, which is dronesafetymap.com. These are both by Altitude Angel, and they're very useful for looking at a lot of these things. And with the Drone Safe app, you've got the ability to look at the map through a number of different sort of filters with an OS map, satellite view and open street map, just to name a few. 

So the site details, where you're going to fly. You probably already know the address if you've got a survey request. Google Maps can help with finding the precise location and giving you the latitude and longitude, but there are other websites that will give that to you as well as the height. Is the site easy to get to? Can you drive to it? Is there somewhere to park? Do you need to walk the last bit? And is the site going to be locked? Do you need keys or someone from the site to give you access so you can get in? 

And also, make sure you've got all the contact details that you might require when you get to site, so you might want the person who's requested the survey, the site manager or the landowner’s contact details, local police, local hospital, local air traffic control. So all these may be useful and things you don't want to be looking up if anything goes wrong. And also is there any special or specific PPE that you might require for that particular site? You need to know which air space you're going to be flying in. So there's a number of sites that will help you see which air space you'll be flying in. Drone Safe app is very useful for this, but you can also use paper maps, air navigation maps. 

So normally or usually, we're flying in G airspace, which doesn't require any additional permissions, well, from the old-- Other airspace may require other permissions or a phone call or an online form to let the air traffic control know that you're going to be there and to get additional permission. If this is required, it's always good to plan ahead and make sure you submit requests with plenty of time as it can sometimes take a while for these to be processed. 

NOTAMs, so this is Notice to Airmen. These can be permanent or temporary in time specific, so it's good to check regularly because your site might not have anything when you are planning weeks in advance, but when you check the day before, something might show up. So these can be things like a firework display, low-flying aircraft, a hot air balloon show or permanent things like high-frequency radio transmitters. All of these things could affect when or how you fly your drone on the site. 

And you need to make sure you've got permission from the landowner, where you're going to take off and land, and depending on the airspace, you might need additional permissions. If you're flying within a military air base restricted area, you might need additional permissions as well, or you will do, and it could be that if you're flying with [indistinct], you might need local authority permission. So again, make sure you check and get these ahead of time. So on the map on the screen, it's from the drone safety-- sorry, the Drone Safe app, and it will show things like areas of increased risk, controlled traffic regions, or CTR, and it will also show up user-report flights. So, for example, you can see a squiggly pink line, which is a user-reported flight on a railway line. So it's good to check to see what's going on in the area. 

OK, so looking at the terrain of where you're going to be flying, the OS map on the Drone Safe app is really good for looking at this. You can see how steep or flat the site is. Check if the site is in an urban or rural location, and see what sort of-- any water courses around. Is the ground where you need to walk going to be boggy or marshy ground? It may be difficult to walk to get to where you want to be taking off, so is there alternative routes? Is there somewhere closer that you could park? Just seeing what's around. And also, proximity to roads. So Google Maps gives you the ability to measure distances. You can check if you're going to be able to maintain a safe distance from roads. For example, you don't want to be too close to motorways. And also, seeing if there's any farms of wildlife. Any sheep could be an issue, or cattle in fields you might need to be aware of. 

OK, so we've got proximities. So looking out for any airports or helipads that might be close by. Also things like glider schools or model aircraft clubs. So these things might be in the area, and you might want to give them a ring if you're going to be flying in the area. 

Other restrictions such as prisons, military bases and nuclear power. So some of these will have restrictions on them that will prevent you from flying your drone. So this doesn't necessarily mean that you can't fly your drone at all here, but it does mean you need to get permission beforehand and the ability to unlock that feature on your drone to be able to fly there. So again, plan with plenty of time to spare.  

OK, so looking at any hazards. So things like power lines and transmitters. So if there's some of these, powerlines, on your site, it's not necessarily going to stop you flying, but it might change where you might plan-- how you plan to fly the drone. You want to make sure that you've got enough separation distance if you're flying far enough above them or flying at a different angle so that they're not going to get in the way of a safe flight.  

We've got sensitivity such as parks, golf courses, nature reserves. Things like parks, you might want to make sure that you're flying very early, so before there's many people there, and just being aware of what's around the site. Talking about people, you need to look out for public footpaths. Don't be surprised if when you're on your site, someone walks up behind you if there's a footpath that goes through the site. Busy roads such as motorways might be treated as large crowds or congested areas, so if there's a very busy road, you don't want to be-- you want to make sure you're able to maintain some separation distance or flying safely. Houses in the area. You might want to inform them that there's going to be a drone flying, and keep in mind privacy, so you don't want to be filming into windows. Maybe set your flight from a different angle or just vertically looking down. 

OK, and weather. So this is very fast changing, and it's difficult to predict too far in the future what the weather is going to do. But you can use long-range forecasts, but make sure you're checking back regularly, up to the day or the even the hour of your flight to see what's happening. So very cold weather can affect batteries and your drone, and your drone may not take off if it's too cold. Again, preplanning is really useful for this. You might be able to keep your batteries and drone insulated or warmer insulated bags, but that's no good if you get to the site and all of these items are already very cold. Also, cold weather, it could easily affect your ability to control the drone. If you've got numb fingers, you're not going to have full control over the drone. 

So the wet weather. So think about how your drone is designed. Can it withstand wet conditions? If it can't, well, then you're not going to be able to fly if it's rainy or if it's misty. You don't want moisture to get inside the drone and stop it working. But also, if it is raining or misty, how is that going to affect the data that you're collecting for your remote survey? If you've got photos that all you can see is mist, then they're going to be no good. Same with the rain. If your drone can fly in the rain, it's very possible that the data it's going to collect in those conditions aren't going to be suitable. 

Also, keeping an eye on the wind. So it's not just the overall wind but also the gusts and to remember that it usually gets windier the higher up you go. And what your drone might be very comfortable flying in, or can fly within its conditions, its limitations might be fine for a higher-mapping mission, but if you're flying very close to buildings, you might want to ensure that the wind is not so gusty so there's no chance that your drone could be affected by the closeness of a building if the wind can act in different ways. So there are lots of weather apps to use. The one I've got on the screen is UAV Forecast, and you can set this with the parameters of your drone for its tolerances, and it gives you a suggestion of if it's good to fly or not. 

OK, so once you've done your pre-site assessment, when you actually get to site to fly for your survey, you need to see if anything has changed. Is there anything different from what you've seen previously? Have a good walk round site. See if there's any hidden dangers, any pits that you could fall in. You want to make sure you've checked the temperature and wind at the actual site, and identify your take-off and landing area, and it's always good to have an alternative area just in case, while you're up in the air, some sheep come and invade where you're going to land and you need somewhere else to put the drone down. 

Also, think about when you're planning your flight. Are you able to see the drone for the whole flight? Do you need to think of where you're going to walk so that while you're flying over a building you can keep the drone in sight at all times? And also, does the site need any extra people to cordon off areas? Do you need some additional signs to make sure that you don't have people wondering into the site? You can keep the site safe and in control. And if you do have an observer, do they know their role? Do they know what to do in an emergency? Do they know how to get the drone down? And just think, what exactly are you trying to get from this flight? What's the mission? What are you trying to do? And when you're satisfied that everything is safe, everything is in your control, it's up to you, the drone pilot, if you're happy, whether you're going to fly or not. 

So I've got a poll question here. Hopefully, it should be very easy. See what you think. So which of the following weather conditions are likely to prevent you flying your drone? A. Fog; B. Light drizzle; C. Wind with strong gusts; and D. All of the above. And I can see most people are going all of the above, which is absolutely-- depending on the drone, any of these could prevent you from flying your drone. OK, and I will pass on to Leon now. Hello, Leon. 

Leon [01:03:19] Hi. Thanks, Lizzie. Hello, everyone. My name's Leon Walsh. I'm one of the senior structural engineers for Historic England and also hold a permission for commercial operations, allowing me to fly unmanned aircraft systems professionally. I've been flying drones myself as a hobbyist for a number of years, and I've seen their potential for assisting with structural inspections. Using a drone allows the engineer to visually inspect parts of a building not easily seen from the ground level, without the need for scaffolding or an elevated platform. 

The aircraft I use is equipped with a visual and a thermal camera. The thermal camera can help detect temperature differentials, highlighting where there may be cooler areas of the structure, potentially indicating dampness. It can also be fitted with a carbon fibre cage and spotlights, allowing the safe use within buildings or structures. 

Often, particularly with historic structures, the erection of scaffolding or access by a cherry picker may cause damage to the historic asset or may be difficult or costly due to the height of the structure, the surrounding topography or adjacent buildings. Although a drone only allows a visual inspection, it can quickly highlight areas which may require further, more detailed investigation. 

One of the most common causes of degradation to a building is ingressive rainwater, whether that be due to effective or blocked rainwater goods, missing roof coverings or water penetration in the wall head directly. Saturation of the [cover?] wall will cause damage to the masonry and lead to rotting of timber elements such as the roof and floor members, as well as damage to the internal wall finishes. The source of water ingress into a building is often difficult to pinpoint, but an initial aerial inspection can be very useful and quickly highlight defects such as blocked gutters or cracked flashings, etc. 

On the left-hand photograph, you can see that there is an area of roof with numerous slipped tiles and a cracked skylight. From the photograph on the right, we can see that the gutter is blocked with vegetation, and the end of the gutter also dips down at the end, and there's also diagonal crack, which you can just see here. Hopefully, you can see my arrow there. 

For structural engineering inspection purposes, in most cases only photographs or video are required, although photogrammetry and laser scans can produce fantastically detailed digital models, which have many uses. I use the drone as an eye in the sky, giving me a close-up image of difficult-to-reach areas or a general overview of a structure of interest. 

Remote inspection drones are very useful when inspecting dangerous, difficult-to-access structures. When flying a drone indoors-- sorry, wrong – outdoors, it is a requirement to maintain a visual line of sight. Indoors there is no risk to other air users, and therefore, drones can be flown within buildings out of sight of the pilot. In this scenario, the use of a cage would be recommended to prevent damage to the drone should it make contact with the structure. The caged drones can also [indistinct] tunnels, wells, culverts, factory chimneys, which are unsafe to access, like the example on this photograph here. 

However, in some situations, you do have to physically touch the structure to determine the extent of rot in a timber element or the depth of a crack within stonework. To my knowledge, drones are not currently capable of this, although who knows what the future of drone technology holds? 

I'm now going to show you some structures where the drone has been used. On the photograph on the left, it was obvious from the ground that the chimney pot had partially fallen through the flaunching on this grade II-listed house. However, the extent of repair required and the stability of the pot could not be confirmed from the ground. In comparison, on the second photograph, on the right, the defect was not visible from the ground but will clearly allow a significant amount of water ingress into the building through the chimney stack. 

At this scheduled ancient monument heritage railway site, a length of lead flashing had been stolen from the roof of the waggon shed, along this line here. The drone was used to assess the damage caused and estimate the amount of lead stolen. During the investigation, I was also able to view other parts of the site very quickly. This potentially would've required multiple visits, several hours' work and the use of an elevated platform of scaffold, had it not been for the use of the drone. 

On the bottom right photograph, you can also see that from above, it's quite clear that the point in between the gable copings is missing, allowing water ingress into the wall, which is like to have caused settlement of the fine material within the wall, leading to instability and potentially subsequent cracking. Again, at the same site, I was also able to inspect this significant corrosion, which has caused a platform on one of the light towers to partially collapse, which you can see bottom left there. 

Following a devastating fire at this grade I-listed church, I did a drone survey to inspect the wall heads and assess the extent of the damage to the stonework at height from both inside and outside the church. Something which would've required the structure to have been cleared and made safe to allow an erection of platforms, scaffolding or a large, elevated platform. 

The West Tower at Furness Abbey in Cumbria recently had a soft capping applied to the wall. You can see here before and after photographs. The drone allows us to monitor the growth of the capping and ensure that it takes hold and protects the wall head as it should do. We were also able to check the condition over the changing seasons. 

Here you can see a thermal photo of the wall head, compared with the same visual photo, which in some areas, which shows in some areas the turf covering is thinner, where the soil beneath has warmed quicker than the thicker grass areas. We will also be able to monitor these locations to ensure that the ground does not dry out, creating a void in the capping, which could hold water and potentially lead to damage to the wall. 

The previous slide showed just a few of the applications for engineering inspections of historic buildings. In the near future, as Paul has already mentioned, we will be using a remote-access drone to inspect wells and culverts, using the drone in locations that would have previously required specialist or roped-access inspections. 

Drone technology in their use in many areas from photographic surveys to farming and medicine delivery has increased significantly over recent years, and the new remote inspection drones, such as the one pictured here, will increase the possibilities for structural inspections in difficult-to-reach areas. I'll now hand you back over to Paul. 

Paul [01:10:16] Thank you very much, Liam. Thank you to David and Lizzie for their parts of the presentation. Thank you also to the 183 people who are still hanging on. I just wanted to have a few closing slides. The title of this was drones for remote inspection. You may have gathered that we haven't spent the whole thing talking about remote inspection. We've talked about the use of drones to capture images that are suitable for remote inspection, but hopefully, you've got the message that there's a little bit more to it than simply buying a drone, going out to a site like Thornton Abbey Gatehouse, as shown in the picture there, flying a drone and capturing imagery. 

You have to think about the regulations. You have to plan the visit before you can even get the drone out the box on site. But once again, I just wanted to summarise that a drone, yes, there's a lot of fancy tech now actually being applied to a drone. Drones can cost anywhere between £500 up to £30/40,000, but they are simply a platform for carrying something, and that carrying something, whether it's a camera, that needs to be used in the correct way as well. David highlighted the new regulations that have come into place, that they're not just for-- well, it used to be the commercial, but it's all about the risk involved in using drones. 

To fly a drone close to a building brings in risks of its own. It brings in risk to the people that might be nearby. It brings in risks to the actual structure itself, so hopefully, do some prework, looking at the regulations. Planning what you can do will hopefully enable you to fly your usual drone for work in a safe and, well, not risk-free but minimised risk form. 

In heritage – I've said this before, and I'll say it again – the drones do have a big part to play across heritage. For instance, here you've got an image from the Appleby House, the Heritage Action Zone works that we've been involved in since 2017, which is linked to the effect of the devastating floods that have unfortunately happened in Appleby on a number of occasions and the impact of them on a structure such as the little, white, terraced building that you see in the middle of that shot there.  

A drone, yes, it can fly. It can actually give you sort of coverage to see if there's a tile missing, as highlighted by Leon, but it can also give you imagery that can enable you to model and map the entire structure, which is what we've been doing as part of the project for our colleagues in Historic England. Capturing an image such as you see on screen does take a lot of preplanning, particularly where you've got roads, vehicles, people gathering. So once again, it needs to be preplanned very carefully. 

And I highlighted some of the applications that we've been using them within Historic England. Just a sort of snapshot of some of this work. You've got the image in the bottom right is one of hundreds that Lizzie took during a detailed survey for English Heritage. It was a church called Saint Mary's Church Kempley in Gloucestershire. 

As well as giving imagery, it enabled them to condition-survey and condition-map pretty much all of the fabric that's visible in that structure. The images that she took enabled a full 3D survey model to be generated. And this is something that we'll talk in more detail on in the third of our sort of seminars in March. 

The image at the top though, as well as in my opinion winning the selfie of the year award. It's a fantastic photo – Dave [Went?] flying his drone up on Rosedale, Rosedale Moor. It highlights the archaeological application. However, I think you'll notice that he's got a heli-- well, a sort of a drone pad. He's got cones out. Even using them in an environment like that, you have to think about the risk involved. Admittedly, there's probably not that many people passing, as Lizzie mentioned. If it's on a footpath, you might get someone just walking up without you knowing because they're actually on a public footway. 

The image in the bottom left is one taken from one of the photographers of Historic England, Steve Baker, who works in the public engagement side, within Historic England. Effectively, they're using drones to raise up their cameras. They do a lot of fantastic work from ground level, terrestrial photography, and drones have taken their work to, effectively, a new aerial level, so it enables them to capture images of sites and providing a very visually dramatic context image. They're not particularly focused on the survey applications, but they do know what to do with a camera, and equally, they're increasingly using drones in similar ways. 

But this is the final slide, the final bullet point. Going back to the demo that we first encountered drones back in 2008. Drone development is moving very rapidly. We're fortunate that we're able to sort of keep, well, not ahead of the game, but I think we're on the game, so to speak, by the links that we have in the industry and the commercial providers. But going back to that demo, even there you will see the gentleman in the blue coat – that's Steve Garland – he's actually wearing the virtual goggles that showed what the drone, the Microdrone, was seeing. So you can see he's looking in a completely different direction from everybody else, but he's not keeping in visual line of contact with the drone. The other people are just sort of trying to follow it. It's a bit like spot the drone competition. But even then, it was capturing imagery that we can reuse, particularly within a photogrammetric context. 

So within the remote inspection theme, the imagery that's collected even from 2008 we can use, but with all of the tools like artificial intelligence that's built in to, say, the latest DJIs, drones, autonomous flying. There is a certain amount of autonomous flying possible these days, and we may look at that in the future. Then you've got machine-learning algorithms within the analysis. So for instance, you can feed a whole series of images through, and potentially, it could sort of pick out-- say, if it's a metal structure, you can pick out corrosion with you having to visually pick it out, or it could pick out damp, sort of condition analysis, that sort of thing. 

So I think the future is looking rosy for the use of drones within heritage and remote inspection, and these are all things that are possible to the heritage user, so I appreciate we've gone way beyond our two o'clock finish. That's the end of the slides. I appreciate there's been a whole series of questions being picked up on the chat. Apologies that I've not been able to respond to any of them. Thankfully, my colleague Gary Young has been there sort of battling to try and answer. 

As I said, this is the first of three webinars. The next one, we're going to be talking specifically about laser scanning, not necessarily laser scanning from a drone, although that is now possible as well, but we're going to be talking about that and how that can aid the heritage professional, or interested person in heritage, to actually inspect a building. 

And then the third one is going to be bringing back in the capturing of imagery of a drone for geospatial survey purposes. On that note, I will pass back over to Alice, who I think is bringing up various yes/no polls, so I'll leave it with you, Alice.