[00:04.840 --> 00:08.940] Hello everyone and welcome to this virtual 747-400 walkthrough. [00:09.020 --> 00:13.440] I guess one of the advantages of Defcon Safe Mode this year is that we're able to bring you [00:13.440 --> 00:17.720] things like this. But nothing beats being able to climb around and poke on a real airframe, [00:17.720 --> 00:21.960] so hopefully this gives you some insights into the avionics and some secret spaces [00:21.960 --> 00:27.500] on board this very recently retired aircraft. Ken and I work for Pentas Partners in the UK [00:28.040 --> 00:32.220] and we've been very fortunate to have access to end-of-life airframes at a breaker's yard [00:32.220 --> 00:36.660] from which we've learned an awful lot and we look forward to sharing some of these things with you, [00:36.660 --> 00:40.100] especially if you've never seen the inside of Avionics Bay before. [00:41.640 --> 00:46.780] So here we are walking upstairs to door B2 which is the second from the front on the starboard side [00:46.780 --> 00:51.240] and gives us a nice view back over the wing. The observant amongst you will probably notice [00:51.240 --> 00:55.160] there are some engines missing. There should be four but three have already been sold on [00:55.160 --> 00:58.780] as these tend to be the most expensive and sought-after components. [00:59.640 --> 01:03.860] On board now and we're straight into one of the galley areas and this will be where the ground [01:03.860 --> 01:09.320] services teams load those trolleys full of your drinks and in-flight meals, but sadly no fine [01:09.320 --> 01:13.820] dining today as the aircraft is basically pretty empty of everything except the seats. [01:16.720 --> 01:21.100] Let's firstly walk through to the back of the aircraft past the stairs to the upper deck. [01:21.300 --> 01:28.420] The 747 is truly a monster at 71 meters long, that's 230 feet, so there's plenty of space on [01:28.420 --> 01:38.650] this aircraft for a full-class cabin layout. Down here right at the back is the first of our [01:38.650 --> 01:45.730] secret areas which is in fact the crew rest area. One of two, this is primarily for the cabin crew. [01:45.990 --> 01:50.950] Through this door at the back are some vaguely comfy seats and then a small spiral stair leading [01:50.950 --> 02:00.010] up to the crew bunk area. Back up to the pointy end now and first class. As well as the back of [02:00.010 --> 02:04.610] this section is perhaps the lesser known floor access hatch down into the electrical engineering [02:04.610 --> 02:09.970] or avionics bay. You won't find this kind of access on smaller aircraft though. You can just [02:09.970 --> 02:18.170] see the outside hatch is open as well down below at the bottom of this ladder. Let's climb down [02:18.170 --> 02:36.540] into the avionics bay then. This is our main set of avionics, all neatly racked up. Each black box [02:36.540 --> 02:43.620] carries out an individual function and are called line replaceable units or LRUs. For example, here [02:43.620 --> 02:49.180] we have LRUs for cabin heating control, data management and at the bottom the three inertial [02:49.180 --> 02:58.930] reference units for navigation. Looking at the same rack from the other side, now we can see [02:58.930 --> 03:03.850] big bundles of cabling running from the back of the racks to other areas, mostly to the cockpit [03:03.850 --> 03:10.370] which is now two decks above us. Each individual LRU will have discrete cabling up to the switches [03:10.370 --> 03:16.290] or displays in the cockpit and if needed discrete cabling to any other LRUs it needs to talk to. [03:16.650 --> 03:21.070] Most of the cables carry data in the ARINC 429 protocol on this aircraft [03:21.070 --> 03:26.370] and this needs a pair for both transmit and receive. There is no network in the traditional [03:26.370 --> 03:31.010] sense to connect to. You can't just clip into a pair of wires at the back of the aircraft and [03:31.010 --> 03:36.130] gain access to all of these other LRUs. Perhaps fortunately it doesn't work like that on these [03:36.130 --> 03:44.070] older aircraft. One other little secret is that behind the LRU rack are doors leading to the [03:44.070 --> 03:49.490] forward cargo bay. The cargo and avionics bay are pressurized and although it would be pretty cold [03:49.490 --> 03:55.110] and noisy you could, in theory, use this area in flight but I really wouldn't want to. This aircraft [03:55.110 --> 04:00.150] has huge tanks of water in here now and this is because with the engines removed it would be too [04:00.150 --> 04:07.030] tail heavy when actually fall backwards without the equivalent weight. Let's take a closer look [04:07.030 --> 04:12.650] at one of these LRUs. This particular one is for the paravisual display, an indicator which shows [04:12.650 --> 04:18.030] the pilots if they're aligned on runway. They're held onto a standard size rack with a screw thread [04:18.030 --> 04:24.530] and rubber vibration mount. Some LRUs have more than one locking screw. If we pull these out we [04:24.530 --> 04:29.990] find a custom multi-pin connector on the back of the LRU for a cable breakout. This will then [04:29.990 --> 04:36.410] run off to wherever it needs to go in the cockpit. Here we have two of the units involved with ACARS [04:36.410 --> 04:42.490] which is the aircraft's data link system. The CMU acts like a router sending ACARS traffic between [04:42.490 --> 04:48.130] the various radios and the output devices like display units and printers which we'll see later. [04:49.410 --> 04:55.790] Okay let's fly those cables back upstairs via a fairly unique set of stairs to the upper deck [04:55.790 --> 05:09.740] bubble. There's a galley up here too if you remember that for later. Right at the front we [05:09.740 --> 05:25.020] find the cockpit behind the armoured doors. Here we are in the cockpit then. On the left is the captain's [05:25.020 --> 05:30.860] seat and to the right is the first officer's. There are two jump seats as well and behind me is the [05:30.860 --> 05:36.280] flight crew rest area. Just a bunk bed again and a separate toilet that they can use without going [05:36.280 --> 05:41.720] back into the passenger area. On long flights there will be three pilots or more which they [05:41.720 --> 05:48.040] rotate through so someone is always getting some rest. The Dash 400 was the first 747 with a glass [05:48.040 --> 05:53.680] cockpit in that the flight instruments are screens rather than what are termed steam driven dials and [05:53.680 --> 05:59.200] gauges. It would have been a flight engineer too but their role is now computerised for the most [05:59.200 --> 06:04.560] part. Each pilot has their own control column or yoke which is directly connected to the control [06:04.560 --> 06:10.440] services by wires, pulleys and gears on a Boeing. The centre console is mostly taken up with the [06:10.440 --> 06:16.880] multi-function control and display units, throttles and controls for the radios. They also have a [06:16.880 --> 06:22.680] primary flight display right ahead of them and a navigational display. Both are independent. [06:22.680 --> 06:28.800] In the centre are the ICAS engine indicating and crew alerting system displays which show [06:28.800 --> 06:34.540] the status of all the major systems like engines, fuel, electrics, hydraulics and also comes up with [06:34.540 --> 06:42.680] log style setting messages in yellow or red depending on severity. So let's power up. We have [06:42.800 --> 06:47.620] a single ground power unit available. We should have two really for a 747 so we need to be a bit [06:47.620 --> 06:53.480] careful on power use. By pressing the overhead button to tie in ground power 1 most things come [06:53.480 --> 07:01.100] alive. You'll notice there's definitely no key. After a few minutes the primary flight display [07:01.100 --> 07:08.040] showing the artificial horizon and flight director bars and the navigational display come up. Here I'm [07:08.040 --> 07:12.740] sat in the first officer's seat on the right so the primary flight display is on the right and [07:12.740 --> 07:23.260] the navigational display on the left. My lower ICAS display shows the electrical buses one for each [07:23.260 --> 07:29.440] engine but as you can see from the upper display we have three engines missing. The aircraft will [07:29.440 --> 07:34.760] think there's a fire as the detection loops aren't connected but obviously we're not really on fire. [07:35.220 --> 07:40.880] I can also use my MCDU to access the ACAR system that we saw downstairs in the avionics bay. [07:40.920 --> 07:45.900] There are lots of things I can do through ACARS but that's the topic for another of my talks. [07:48.260 --> 07:53.060] Also in the cockpit are some other interesting bits of avionics like this navigation database [07:53.060 --> 07:58.100] loader that still uses three and a half inch floppy disks. This database has to be updated [07:58.100 --> 08:04.040] every 28 days so you can see how much of a chore this must be for an engineer to visit each month. [08:05.460 --> 08:10.540] There is also a quick access recorder which is used for gathering lots of data about the aircraft's [08:10.540 --> 08:15.520] health. At the end of each flight or near enough an engineer will remove the PC card [08:15.520 --> 08:21.520] although this one actually has a CF to PC card converter and download the data which helps with [08:21.520 --> 08:26.120] predictive maintenance or detecting if there's been a heavy landing or tail strike for example. [08:26.120 --> 08:31.120] More and more aircraft are starting to become e-enabled which means this data is streamed in [08:31.120 --> 08:36.220] near real time back to the airlines and engine makers over SATCOM so they can have replacement [08:36.220 --> 08:43.780] parts ready and waiting for when the aircraft next lands. Now then, in-flight entertainment. [08:43.900 --> 08:48.740] There's no wi-fi on this 747 but under the stairs down from the upper deck the cabin [08:48.740 --> 08:54.240] services director has a small office and this is where the 747's IFE is driven from. [08:54.240 --> 08:57.740] There is a small touchscreen PC here which is actually running [08:58.580 --> 09:04.600] NT4. This can be used to change aspects of the system, add the day's news broadcast video, [09:04.600 --> 09:10.220] reboot seat boxes and even turn individual seat lights on and off. Above this are the digital [09:10.220 --> 09:15.940] media servers themselves which contain all the movies and so on ready to stream to each seat. [09:23.030 --> 09:26.190] There's also the boarding music and safety announcement controller [09:26.190 --> 09:38.330] which just plays off digital audio tape. There's even a little printer in here which is linked to [09:38.330 --> 09:43.730] the ACARS system so the cabin services director can print things off if they need to. [09:45.850 --> 09:50.690] And lastly, I want to leave you with a little secret. Remember the upper galley? Well, [09:50.690 --> 09:55.750] there's a lift to take catering cars between the main and the upper deck which is pretty cool. [10:01.680 --> 10:06.500] Alex, thank you for the tour of the 747. Absolutely fascinating. Now, why didn't [10:06.500 --> 10:12.240] you do this interview in the in the 747 itself? Well, yeah, we really should have done but it was [10:12.400 --> 10:17.880] a bit, you know, kind of confined in there and in the current COVID environment doing it with [10:17.880 --> 10:23.440] masks and things would have been a bit weird. So yeah, we've come back to do it in the sim. [10:23.440 --> 10:28.740] So it's our simulator rather than the the cockpit of the 747. That's fine. Great. Yeah. [10:29.140 --> 10:37.180] Safety first, right? Quite right too. Now, one of the things that I think is a bit of a game [10:37.180 --> 10:41.860] changer is the fact that so many airframes are being retired right now. What difference does [10:41.860 --> 10:47.020] that make for us as researchers? Aircraft themselves are really expensive beasts, you know, [10:47.020 --> 10:54.620] and even if you had all the will in the world, airlines and airframe manufacturers won't just [10:54.620 --> 10:59.580] let you go and pen test an aircraft because you don't really know what state you're going to [10:59.580 --> 11:05.440] leave it in. It's not like an office network where you can go and reinstall and clean things up. [11:05.760 --> 11:11.180] Recertifying avionics and whole airframes is ludicrously expensive and even if you were able [11:11.180 --> 11:17.300] to have some assurance that you've cleaned up the mess the pen tester has left. So being able [11:17.300 --> 11:24.640] to sort of do more adversarial testing of an aircraft in a flying state is not something that [11:24.640 --> 11:30.760] we really get to be able to do. So, you know, it's not a silver lining, I have to say, but [11:30.760 --> 11:37.280] one of the results of the COVID crisis is that airlines are bringing forward a lot of their [11:37.280 --> 11:45.260] programs, particularly of these larger types like the 747 and the 380s. [11:45.880 --> 11:51.680] And as a result, they're going to salvage yards. They're not really going to fly again [11:51.680 --> 11:58.380] in their current state. No one really wants 747s anymore. So yes, the avionics [11:58.960 --> 12:06.400] may get a second lease of life, but the actual aircraft themselves are unlikely to be able to [12:06.400 --> 12:10.500] fly again. And that gives us a really good opportunity to go and have a look around. [12:11.060 --> 12:14.920] Yeah, so in the past, we've looked at some airframes. I think probably the oldest one [12:14.920 --> 12:19.500] we got to have a play with was a 10-year-old A320 or so. But even then, it doesn't really [12:19.500 --> 12:23.800] represent what's coming off the production line right now, does it? So, you know, last year for [12:23.800 --> 12:29.700] Defcon for the village, we went and bought some LRUs, but even those were upwards of 20 years [12:29.700 --> 12:35.480] old. So do you think it's a game changer, the fact that we're seeing some slightly more recent kit [12:35.480 --> 12:41.600] being scrapped or decommissioned? Yeah, for sure. I mean, the 747 that we [12:41.600 --> 12:49.940] just did the video to around was 23 years old. But remember that the design life cycle of these [12:49.940 --> 12:56.580] things is 30 years. And there's a decade or more of design work that goes into an aircraft before [12:56.580 --> 13:02.700] it even goes into production, and then 20 odd years of service. So what people are designing [13:02.700 --> 13:10.900] today will still be in service in 30 years time. And it's really difficult to anticipate all of [13:10.900 --> 13:18.080] sort of future security needs and requirements. So yeah, what we've seen today is obviously not [13:18.080 --> 13:25.000] state of the art. And there are differences between 747 that we looked at and more modern [13:25.000 --> 13:31.480] aircraft like the A380 that are flying today. Big differences in the way that their avionics are set [13:31.480 --> 13:36.460] up and how the networking is done on board. Yeah, so it's important to remember that particular [13:36.460 --> 13:40.880] plane was still flying just over two, two and a half months ago. And I think I actually flew in [13:40.880 --> 13:46.980] that very plane as a passenger last year. So it is representative, it's just the scrappage [13:46.980 --> 13:51.540] programs are being accelerated. And I also went through the avionics bay actually dating the [13:51.540 --> 13:55.380] install dates for many of the components. And there's a lot of kit in there, but it's only [13:55.380 --> 14:00.040] five to 10 years old in some cases. So it's not all 23 years out of date. [14:00.040 --> 14:05.900] No, no. And a lot of it is reused. So the ground proximity warning system, [14:05.900 --> 14:12.180] for example, those LRUs are pretty much interchangeable between any aircraft. I mean, [14:12.180 --> 14:21.540] I've seen the same exact LRU make a model on the 747 as I did an Airbus A320. And they go for [14:21.540 --> 14:28.580] $20,000. I mean, it's like a tiny little box, and it's $20,000. So it shows you, you know, [14:28.580 --> 14:33.240] yes, stuff is coming off things that have been scrapped, but it is still current and flying. [14:33.320 --> 14:35.780] And it is megabucks if you want to go poke at them. [14:36.020 --> 14:41.360] So obviously, 49 carries a lot of heavy wiring as a result of it. Now, I know that [14:42.120 --> 14:48.700] the 777 used an inductively coupled bus called ARINC 629, but that was really only used in the [14:48.700 --> 14:55.600] 777 itself. More recently, we've seen a move towards AFDX or ARINC 664. How does that change [14:55.600 --> 15:02.680] the risk profile of the plane to you? So 664, and aviation loves its acronyms and numbers and [15:02.680 --> 15:12.280] stuff. So, but 664 is basically based on Ethernet. It is Ethernet with some extra quality of service [15:12.280 --> 15:18.400] layers on top to make sure that flight critical things can always talk to each other. So there [15:18.400 --> 15:27.520] is basically a fiber network around more recent aircraft like the 777X, the 787, and the A380. [15:28.000 --> 15:34.340] So there is a fiber network and everything plugs into that fiber network. And instead of these [15:34.340 --> 15:44.580] discrete black boxes that we saw on the 747, and this whole rack of individual black boxes for want [15:44.580 --> 15:50.500] of a better word, then there is basically a single compute crate. In fact, there's a pair for [15:50.500 --> 15:57.660] redundancy. But there's an A side and a B side computer. And things just run as software. So [15:57.660 --> 16:03.260] there's typically a real-time operating system like VXWorks that handles the flight critical [16:03.260 --> 16:09.140] stuff, and then there tends to be a Linux side for less important things. And things are just [16:09.140 --> 16:17.120] run as applications on these computational nodes. So that does mean it's starting to look a bit more [16:17.120 --> 16:23.980] like a traditional IT network, albeit one that's kind of hardened and more resilient in that [16:23.980 --> 16:29.840] regard. But, yeah, if you don't get things right, and I'm sure we've all seen it on office networks [16:29.840 --> 16:35.160] and traditional office firewalling, if you don't get IP tables right, then that potentially means [16:35.160 --> 16:41.880] traffic can move from one segmented zone to another. And that is true on aircraft. But [16:41.880 --> 16:46.380] obviously, you're still going to need physical access. Things that I think we noticed from [16:46.380 --> 16:51.420] looking at some navigational databases we recovered from airplanes, particularly those [16:51.420 --> 16:57.800] on floppies, is there wasn't any code signing. There wasn't any cryptographic validity. So, [16:57.800 --> 17:01.140] again, less of a problem where you're physically having to visit the plane and there's physical [17:01.140 --> 17:05.900] security in place. But as we move towards, you know, sort of the idea of updating remotely over [17:05.900 --> 17:11.320] the air, do you think that's more of a problem? Well, where manufacturers have moved to this [17:11.320 --> 17:17.240] over-the-air deployment model, they have implemented some code signing, which has [17:17.240 --> 17:22.980] brought its own problems, actually, recently, because that code validity certificate is also [17:22.980 --> 17:29.840] only valid for a month. So if you're trying to do updates onto an Airbus at the moment, [17:29.840 --> 17:34.440] you actually have to update the certificate verification list in the certificate chain [17:34.440 --> 17:39.780] before you can do anything else. So they have thought about this as they've started to [17:40.320 --> 17:46.560] make these e-enabled aircraft, for example. And on the Boeing side, there are some actual [17:46.560 --> 17:54.900] physical data interlocks on the aircraft. So although you can stage software updates [17:54.900 --> 18:00.980] and navigation updates, for example, onto the aircraft, they are held in an area until [18:01.640 --> 18:07.720] either a pilot or a maintenance engineer physically operates a key switch and selects where that [18:07.720 --> 18:14.100] software update should go. And there are other physical interlocks. So the aircraft actually [18:14.100 --> 18:19.720] has to have its weight on wheels switch closed as well. So the aircraft has to be on the ground, [18:19.720 --> 18:24.400] it can't be flying. And so one has to physically operate a mechanical switch [18:25.060 --> 18:32.320] in order to update that particular part. So there are some safeguards. But yeah, you're right, [18:32.320 --> 18:40.980] there are still a great reliance on CRCs and that kind of thing floating around in the aviation [18:40.980 --> 18:47.120] industry. And if you speak to people, there does seem to be a bit of a misunderstanding between [18:49.760 --> 18:55.660] integrity in that there is some sort of CRC magic number type thing to make sure the message [18:55.660 --> 19:04.940] or update hasn't been garbled in transmission versus actual message signing, so that you know [19:04.940 --> 19:10.840] that that software update or message has actually come from the person that says it's come from. [19:10.960 --> 19:15.760] There's a lot of connectivity being established on planes. And a particular technology I'm quite [19:15.760 --> 19:20.260] interested in is Gatelink, which is used to upload and download, for example, [19:20.260 --> 19:25.900] pasture and manifest information, but also things like movies and stuff. So someone physically [19:25.900 --> 19:32.480] doesn't have to put a CD or floppy crikey into the IFE. What other things are we seeing connected [19:32.480 --> 19:38.480] to planes on the ground? Primarily, it's the health and maintenance data of the aircraft. [19:38.480 --> 19:47.940] There's this big drive from the part of the manufacturers to have literally cloud offerings, [19:47.940 --> 19:53.580] so that you as an operator can see the status of your aircraft in real time. [19:54.120 --> 20:01.140] I mean, some of it is really cool in that they can even see how long it takes an individual valve [20:01.140 --> 20:07.680] to open or close, that if this particular valve is now taking a fraction of a second longer to [20:07.680 --> 20:14.180] open or close than it was, then maybe we need to arrange maintenance to come out and change that [20:14.180 --> 20:20.440] valve before it becomes a problem. And the aircraft requires more maintenance and more downtime. [20:20.440 --> 20:25.480] And remember that every time the aircraft is sitting on the tarmac, it's losing money for [20:25.480 --> 20:32.020] the airline. So to keep our fares down, we want to maximise how often these things are flying, [20:32.020 --> 20:36.000] but in a safe way. That picks up an interesting piece from a couple of years ago. A security [20:36.000 --> 20:39.700] researcher claimed to have accessed the thrust management computer from the inflight entertainment [20:39.700 --> 20:45.500] system. What's your view on that? Do you think that was a real issue? Or do you think [20:45.500 --> 20:51.300] perhaps the media got a bit excited about it? I think it was thoroughly investigated by [20:51.300 --> 20:59.240] everyone. And knowing the airframe manufacturers, they do genuinely take reports of this nature [20:59.240 --> 21:05.900] pretty seriously. Most of them have avionics labs where they have everything in pieces on [21:05.900 --> 21:13.120] the bench. And they often have a dedicated cyber security team that can take reports of this nature [21:13.120 --> 21:17.860] and actually go and replay them on the bench and even on real airframes if they want to. [21:17.860 --> 21:25.120] So I know it was thoroughly investigated and kind of debunked at the time. I think it was [21:25.120 --> 21:30.640] perhaps a media jumping on the story rather than the individual in that particular case. But as [21:30.640 --> 21:37.500] we briefly spoke about earlier, there is ARINC 49 flying around between the flight management system [21:37.500 --> 21:42.980] and the inflight entertainment for telling you where you are. That's just part of how it works. [21:42.980 --> 21:50.780] But that is a worldwide system and we have found that in our research. I obviously can't speak [21:50.780 --> 21:55.700] as to the exact operator and aircraft involved in that previous instance. But where we've [21:55.700 --> 22:01.980] gone and deliberately looking, we've not found at this point any two-way communication between [22:01.980 --> 22:09.480] passenger domain systems like IFE and the control domain. And there is actually this sort of DMZ [22:09.480 --> 22:15.740] almost of the information services domain that sits between the two. So to jump between [22:15.740 --> 22:22.860] essentially two layers of segregation will be tricky in my opinion. Yeah, from everything I [22:22.860 --> 22:28.240] looked at, it doesn't substantiate some of the claims that we've seen. Certainly we haven't [22:28.240 --> 22:33.360] found a way to compromise aircraft control from the IFE. It strikes me that sometimes we're looking [22:33.360 --> 22:37.340] in the wrong place. Everyone gets very excited about airplanes because they're new and unusual [22:37.340 --> 22:42.520] technologies and it's great for us inquisitive researchers. But frankly, probably the most [22:42.520 --> 22:47.080] likely area to cause disruption is going to be the ground system. So if a plane can't dispatch [22:47.080 --> 22:50.840] because the ground systems are down or the maintenance systems are down, it doesn't go [22:50.840 --> 22:55.380] anywhere. So I often think that planes get really interesting and lots of fun and I think it's great [22:55.380 --> 22:59.940] that we can help assure their security. But really you need to watch out for those ground systems, [22:59.940 --> 23:07.700] right? Yeah, definitely. I mean it just reminds me of flying out to Defcon almost a year ago [23:08.240 --> 23:15.580] and a particular airline that pretty much all of us were traveling with to Vegas had a massive [23:15.580 --> 23:22.940] outage of its passenger information system. So none of the check-in crew at the airports [23:24.040 --> 23:27.920] could scan your boarding pass and get you onto the aircraft. They were having to do it [23:27.920 --> 23:35.060] like literally pen and paper, all by hand. Thousands of people at this one airport. The [23:35.060 --> 23:41.280] queues were out of the terminal around the car park. Yeah, and this was global. That's a huge [23:41.280 --> 23:45.780] amount of disruption and cost and did a really stellar job of getting us onto the aircraft in [23:45.780 --> 23:52.560] time pretty much. But you can see just how little things like this can have a real snowball effect. [23:53.160 --> 23:57.060] So certainly before the lockdown I used to fly pretty much every single week and [23:57.060 --> 24:02.820] I don't know about you Alex, I feel very comfortable with flying, being a passenger, even fully in the [24:02.820 --> 24:07.360] knowledge of how aviation systems work. I'm very confident in their security. How do you feel about [24:07.360 --> 24:12.840] it? Yeah, I mean, I think it's really important that, you know, we're not here to scaremonger. [24:13.660 --> 24:18.420] Like any industry, there are areas of improvement and I'm pretty sure they would be the first to [24:18.420 --> 24:23.440] admit that. But do any of these deficiencies mean that it's unsafe for people to fly? [24:23.480 --> 24:29.900] No. I'm a pilot. I want to carry on flying for work. You know, I'm friends and family [24:29.900 --> 24:35.820] flying around, so I don't wish them any harm either. So no, I don't think there are any risks. [24:37.540 --> 24:40.780] Great. On that note, Alex, thank you very much. Cheers, Ken. [24:42.480 --> 24:45.400] So thanks for watching. I hope it was useful to you. [24:45.400 --> 24:48.260] If you have any comments or questions, let us know.