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Electronic Conspicuity in the UK
Can anybody help out with a bit of hopefully unclassified knowledge.
For a variety of reasons I'm taking an active interest in electronic conspicuity in the UK. There are multiple systems available, particularly in the GA community: FLARM, PilotAware, TPAS, and so-on and so forth. Recent UK Airprox Board reports have highlighted various proxes between UK light civil, and military aeroplanes - clearly stuff we'd all rather avoid. Can anybody fill me in on what conspicuity systems (mode C, mode S, ADS-B, FLARM, etc.) are being carried on various military assets operating in UK airspace. Also - what traffic alerting systems is anybody carrying? I understand PowerFLARM on the G115 and Tucano fleets?, presumably TCAS on the Globemaster & Herc (but I'm assuming that, rather than know). Is anything else out there? Or if nobody feels they can say on here - a steer as who I can ask officially would be great. G |
Typhoon will be Squawking 3C and using RADAR to clear its flightpath, no TCAS system fitted.
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What would be great would be a £200 ModeS ADSB based system, which would give everyone the screen that the Hawk T2 rear seater has. A fully dynamic display of what the aircraft you around are doing.
That's not going to happen until we all transmit gps data all the time, and the big problem is that where it is needed most, which is <3,000 feet is normally not transponder mandatory territory. Maybe someday. |
Originally Posted by airpolice
(Post 10167242)
What would be great would be a £200 ModeS ADSB based system, which would give everyone the screen that the Hawk T2 rear seater has. A fully dynamic display of what the aircraft you around are doing.
That's not going to happen until we all transmit gps data all the time, and the big problem is that where it is needed most, which is <3,000 feet is normally not transponder mandatory territory. Maybe someday. I think that the next generation, forecast late this year - Rosetta and Aircrew are looking to do the whole hog for around £400. AirCrew.co.uk Rosetta - Pilot Aware The biggest problems, in my opinion, are that we now have five gusting 7 different systems in use globally that aren't universally intercompatible, and at least two of them are using uncertified hardware, that creates a massive problem in fitting them into certified aircraft: whether military or civil. Of course any electronic conspicuity system, so long as crews don't assume they'll see everything out there, is better than no conspicuity system. G |
PliotAware will eventually become the conspicuity Betamax. It uses unlicensed frequencies so will never be certifiable.
FLARM is useful for sailplanes in close proximity with each other and with a few powered aircraft flying from the same site. The CAA has already said that the preferred solution will be based on ADS-B. So the contender for the most likely future system is probably Sky Echo platform plus a display / audio warning system. When I reviewed a number of conspicuity devices a year or so ago, the only one which was of any use was the Trig device which didn't need a display - and gave only genuine collision warnings. I was quite shocked at the 'panel gazing' of many of the GA pilots involved - VFR implies L00KOUT, not staring at some iToy! |
Originally Posted by BEagle
(Post 10167360)
I was quite shocked at the 'panel gazing' of many of the GA pilots involved - VFR implies L00KOUT, not staring at some iToy!
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Originally Posted by BEagle
(Post 10167360)
PliotAware will eventually become the conspicuity Betamax. It uses unlicensed frequencies so will never be certifiable.
FLARM is useful for sailplanes in close proximity with each other and with a few powered aircraft flying from the same site. The CAA has already said that the preferred solution will be based on ADS-B. So the contender for the most likely future system is probably Sky Echo platform plus a display / audio warning system. When I reviewed a number of conspicuity devices a year or so ago, the only one which was of any use was the Trig device which didn't need a display - and gave only genuine collision warnings. I was quite shocked at the 'panel gazing' of many of the GA pilots involved - VFR implies L00KOUT, not staring at some iToy! As others have said, Typhoon and Lightning have a RADAR that will see most puddle jumpers at shortish ranges depending on what the light aircraft are made of. They also have Transponder Interrogators, but these have to be used sparingly in certain areas as they can make lots of traunsponders reply that could cause FRUIT (basically the garbling of the 1090 frequency). However, I also hear that Typhoon is likely to get an ADS-B In/Out capability. Also, the CAMO would have a fit trying to fit this bodge into a military aircraft with all it’s secret wiggly amps potentially being compromised. (For those on here that don’t know then Pilot Aware is the dogs dinner posted below (soon all this will be put in a massive box instead). I for one would not want to trust my safety on this amateur set up.) https://cimg0.ibsrv.net/gimg/www.gmf...bcc28095c6.jpg |
TCAS
I concur that these systems drive the head into the cockpit which is not what I like to see. Another problem, evidenced again today, in somebody receiving a traffic service was informed of traffic (us) and responded with “have him on TCAS.” Whilst I may be being pedantic (who’d of thought?) this shows a misunderstanding of what the system actually provided - I am 99% certain that none of these systems actually provide an RA where appropriate. Or do they? |
So many options. To me some form standardisation is required in displaying the info or the total effect is lost.
PS: Lima Victor, please mow your grass!!! |
I confess that I find it quite comforting when I'm bouncing around in cloud, there's an airliner somewhere above or below me, and they report "we have him on TCAS" - as at least one of us knows the relative position of each other from a threat perspective.
Regarding driving a head into the cockpit, I think we should in that context remember just how large the blind spots are in most civil and transport cockpits. I'm afraid that I don't have any diagrams for modern combat aeroplanes, but here's a Hammer diagram (this presents a 360degx360deg view onto a flat image, like a wall map of the world) for the Jaguar front seat... https://cimg0.ibsrv.net/gimg/www.gmf...7fc72f1ac3.jpg There are blind spots, primarily below - but not that many. Now compare to a Boeing 737 from the Captain's seat... https://cimg1.ibsrv.net/gimg/www.gmf...ea88dfcfa5.jpg There are a lot of blind spots - including even in the pillars which unless they are less than the distance between the pilots eyeballs (typically around 80-90mm) are also a significant obstruction. Plus that it's asymmetric - so if the Captain is the one doing the lookout, she has a lot of blind spots to her right that she can do nothing about whilst her F/O is busy heads in. And most light GA are only marginally better - this is from the left hand seat of a PA28... https://cimg2.ibsrv.net/gimg/www.gmf...915b4f2a50.jpg It's really not hard to see huge blind spots there, and equally there are coincident blind spots - a descending or climbing PA28 has plenty of areas in the direction of travel they can't see. So, I'm afraid I don't buy the argument that a small and well managed period of "heads in", in virtually any cockpit, isn't entirely well spent, if that is spent for nearby traffic on a screen - whether that screen is providing pure alerts, or spacial awareness. Clearly excessive such time is not advantageous but when the aeroplane structure is obscuring perhaps 60-70% of the outside view, spending 5% of one's time (these are numbers plucked from the air with no science behind them, so likely to be the wrong numbers, but you get the idea - 5% however is 10 seconds every three minutes) checking an electronic device for external threads does not seem to me to be excessive. G |
From past experience, those claiming that TCAS/TAS is detrimental equipment which merely "drives the pilot's head inside the cockpit" are likely to be those who haven't flown with it on a regular basis. Used correctly, it naturally becomes part of an effective lookout scan. A brief glance inside is all that's needed, as the pilot looks from left to right during his lookout scan process. The shortcomings of the system are well known and due allowance has to be taken, but seeing a transponding "blip" at a range of up to 12 miles allows the user to take far more timely avoidance than relying on the much shorter range of even the best human eyesight alone.
The reason some pilots say "Got him on TCAS" is probably to reassure the ATC controller so he can perhaps concentrate his attention on another developing situation and make the necessary RT calls to other aircraft, at least for a while. So don't criticise, the pilot is actually trying to ease the controller's workload in order to help others! Having flown a number of different TCAS/TAS equipped helicopters over the past twenty years, (and twenty more before that without it, military fixed wing and rotary plus some civilian stuff) I would now feel very vulnerable without it. It's shown me many times that most pilots don't look out effectively, or don't know the rules of the air. Seeing as we all take the air law exam, (and hopefully no-one actually wants to be involved in a mid-air) it's more likely to be the latter! |
I have called "non-squawking" traffic to pilots and received the reply, "Got him on TCAS". So tempted on those occasions to say, "No you haven't, pay attention, I've just told you it's non-squawking therefore you can't have it on TCAS."
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Originally Posted by Il Duce
(Post 10168381)
I have called non-squawking traffic pilots and received the reply, "Got him on TCAS". So tempted on those occasions to say, "No you haven't, pay attention, I've just told you it's non-squawking therefore you can't have it on TCAS."
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https://cimg2.ibsrv.net/gimg/www.gmf...48405ffb33.jpg Genghis Not too convinced on the accuracy of that drawing for the PA28 - you would have to be sitting in the back seat to see both seat backs that are depicted in your diagram! Here is a pretty typical forward view from the left hand seat of a PA28... https://cimg4.ibsrv.net/gimg/www.gmf...e24100fa2f.jpg |
You might want to check what "180 degrees" means, as illustrated in the diagram, which is a flat representation of a full sphere. Your photograph is probably showing around 25 degrees left and 45 degrees right of forwards, and maybe 30 up and 20 down.
Also, collisions don't necessarily happen head on! That of course is why cockpit view diagrams use either the Hammer of Molinye graticules, that show the full sphere. G (163 hours in PA28s, but trying not to add any more, simply because just about anything else in my logbook is more interesting to fly.) |
Re the Tucano, don't know what FLARM is but I was flying the machine when TCAS was fitted. TCAS was, and presumably still is, a great back up but not a replacement for proper lookout.
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FLARM is basically low power TCAS for gliders, working on its own frequencies and encoding.
G |
Originally Posted by Il Duce
(Post 10168381)
I have called non-squawking traffic pilots and received the reply, "Got him on TCAS". So tempted on those occasions to say, "No you haven't, pay attention, I've just told you it's non-squawking therefore you can't have it on TCAS."
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Is it outside the realms of possibility that geometry / path length / attenuation mean that a transponder return isn't seen by a groundstation but is seen by a nearby aircraft?
G |
Originally Posted by Genghis the Engineer
(Post 10168453)
You might want to check what "180 degrees" means, as illustrated in the diagram, which is a flat representation of a full sphere. Your photograph is probably showing around 25 degrees left and 45 degrees right of forwards, and maybe 30 up and 20 down.
Also, collisions don't necessarily happen head on! That of course is why cockpit view diagrams use either the Hammer of Molinye graticules, that show the full sphere. G (163 hours in PA28s, but trying not to add any more, simply because just about anything else in my logbook is more interesting to fly.) i know collisions can happen at any angle and are dependent on aircraft speed, bearing, heading, climb/descent rate and relative altitude. It also depends on human physiology as well - we don’t see too good behind us as predators! So my point is, that the aircraft design is only a small factor for most modern aircraft - you need to fly something like the Comper Swift where looking out ahead is pretty tricky! The other thing to point out is that the majority of the RAF’s FLARMS are actually PowerFLARMs and so they detect ADS-B as well. If the amateurish Pilot Aware did ADS-B Out instead of some random Betamax format (thanks BEagle) then it would be useful. FLARM is the same, but as the gliders have invested in it then it makes sense for now. But what we need is a common International standard - that is ADS-B - so when I take a Typhoon or A400M to other countries I can see the light aircraft not just some amateur lash-up knocked up in someones shed! |
PS. And the CAA have already said it is their system of choice: https://www.caa.co.uk/News/ADS-B-can...ons,-says-CAA/ |
Indeed, LimaJuliet! Which is why SkyEcho2 looks like becoming the system of choice.
However, traffic warning over the intercom of genuine collision threats as I heard from the Trig system are a must. It was like having an 'e-wingman' with you, except that the warnings were announced in a clear, female Scots voice which certainly gets one's attention! |
I think that a lot of light aeroplanes are flying the PilotAware "amateur lash up built in somebody's shed" and mode-S or ADS-B. Speaking only for my syndicate's aeroplane - TCAS equipped aeroplanes will see our Mode-S, but we'll see just about anything with the PilotAware. Not mind you disputing that PAW is a lashup: getting it faintly neat and tidy in our cockpit was quite a challenge (although we managed, and obviously don't have much by way of classified wiggly amps!), it's an uncertified (and uncertifiable for now) system, and that's a problem. On the other hand it's available, affordable for people spending their own money, and does appear to work.
Anything, thanks those who have contributed what military aircraft are outputting - from responses above I make that... Conspicuity BBMF - FLARM, (Mode-S?) Typhoon - ADS-B Seeing BBMF - FLARM Air Cadets - FLARM Tucano - TCAS 1 RAF Heavies - TCAS I or II Tornado - ACAS(?) Typhoon / Lightning - Primary radar Is that correct? There are gaps there clearly - presumably the heavies all have ADS-B? What are the rotaries carrying? G |
Originally Posted by Lima Juliet
(Post 10168790)
PS. And the CAA have already said it is their system of choice: https://www.caa.co.uk/News/ADS-B-can...ons,-says-CAA/ The FASVIG trial was allegedly completed late 2017, but there seems no report on it. I was at the last RAeS GAG conference where FASVIG proudly announced a trial of six(?) installations, and virtually came to blows with the PAW team who apparently hadn't been in the loop and were claiming a couple of thousand installations. So on the one hand we have a bunch of amateurs with a lashed up system, but it works, seems to be in a couple of thousand aeroplanes. And on the other hand we have a CAA sponsored "professional" trial that seems to have tested stuff in single figure installations, then not actually reported their trial, nor engaged with the amateurs who have been leaving them behind. Whatever else that is, it's a mess. What I am clear in my mind is that we should be concentrating on getting traffic warnings into cockpits - conspicuity to ATC, whilst necessary for other reasons, isn't a solution to collision risk. G |
The answer is simple (allegedly) . Extend lower altitude 'controlled airspace' to cover 99% of the U.K. That way, GA will be able to have their collisions in the remaining 1%, and, of course, the reducing emergency services will be able to predict where they will be needed. A 'Win win' for certain recent 'airspace consultations'. (For the record I am familiar with FLARM, and we are about to fit one to our Glider. However, as a pilot who had 'LOOKOUT' beaten into me from day one, I am a bit concerned that, if mandated, it will become the main collision avoidance system for some. I have a nightmare vision of some pilots heads down, staring at an electronic nav system - never looking out and boreing on regardless until the FLARM Screams! :uhoh:) just IMHO. |
Originally Posted by Lima Juliet
(Post 10168786)
But Genghis those diagrams are very misleading. Because what you can see is very dependent on head position. If I put my face next to the left hand window in a PA28 I can see a lot more than the diagram shows. If I put my head forward I can see a lot more up. Presumably you're familiar with the concept of "Design Eye Position", or DEP which is essentially what's being exploited there - and is standard in evaluating such things. I could slacken off my harness, move my head, massively improve view in one direction - at which point I've removed instruments and other directions from my scan. Of course, yes there may be other ways to evaluate view out of a cockpit, but I'm not aware of them. Can you provide any links to alternative methodologies? Hammer and Molnye are the only two I've ever used, and Hammer I find a little more honest. G |
Yes but the DEP might be a standardisedposition, but it still gives a false impression in my own opinion. Human’s adapt their look out to compensate for the challenges like canopy arches and window frames. However, those sorts of diagrams make no allowance for that. Therefore, in my view (no pun intended), they are misleading. When used with Sky Demon or other software then these devices then the pilot can be warned aurally by beeps, hoots and squeaks. Some even call out the traffic direction or height relative to you. You get what youpay for. As for Pilot Aware’s claims of thousands of users, that is probably how many they have sold. However, I know of many that bought them and used them a couple of times and then stopped - too many wires, loose dongles, intrusive antennae and the requirement for power from a seperate source. I was even offered one second hand for 50 quid, which I declined as you need to keep buying a licence to use it. I have updated your list for you: Conspicuity/Detection Mode S - all military aircraft, some with ADS-B Out in the ES element FLARM - BBMF, all Tutors, all Vikings, Vigilants (until scrapped earlier this month), Tucano and I know they did a trial with Hawk but not sure where that went. The new Prefect is due to get FLARM, but I am unsure on Texan, Phenom, Jupiter and Juno. Pretty much all, except Viking, are PowerFLARM so they also detect ADS Out. Primary and Secondary RADAR - Typhoon and Lightning. Tornado GR4 can use its ground mapping RADAR in a limited air to air mode and does so for finding the AAR tanker, but it is optimised for ground mapping and other modes. E3D and Sea King AEW has primary and secondary RADAR. JTIDS/MIDS - this datalink will receive the RADAR picture from ships, ground RADARs, AEW/AWACS aircraft. This can also show the presence of aircraft that are either a pure RADAR detection or a secondary Mode A/C/S return and display it in the JTIDS equipped aircraft. Many have JTIDS/MIDS capability including Typhoon, Lightning, Tornado GR4, E-3D Sentry, Sentinel R1, Hercules C130, Voyager, A400 and Sea King Mk 7 - there are probably more that I have missed. ACAS/CWS - this has been a long time coming in Tornado and the work from this will likely go on to the procurement of other systems. It is basically a Collision Warning System (CWS) that detects in a similar way to TCAS but has been militiarised for fast jets. Some info here https://assets.publishing.service.go...e_Redacted.pdf TCAS I or II - all heavies, some helicopters and some of the training fleet like Phenom, Tucano and Hawk. Again, I know of quite a few but have not flown all of these. Obviously, TCAS will detect ADS-B Out if it is SIL=1 or above, but those using the Pilot Aware’s GPS for their Mode S ES transponders will pnly be outputting SIL=0. There is RAF representation at the CAA/MOD Electronic Conspicuity Working Group. My understanding is that ADS-B is the favourite over and above the proprietary systems like FLARM, which has a strong global following, or things like the UK-only Pilot Aware. I 100% agree with BEagle. That ADS-B is the ONLY way to go. So many aircraft would see ADS-B if it was SIL=1 or above (ie. from a certified GPS source) and that would include the military. This Pilot Aware phenomena has seduced the Light Aircraft market because it is cheap (although once you buy a battery, a tablet, some software and some velcro, it isn’t that cheap). But the only thing that Pilot Aware emits is around 870mhz that is the ‘free to use’ band that is used for shops RFID tagging, burglar alarms and motor vehicle tracking - that is its real limitation. Also, the chances of it being embodied in any military aircraft is ZERO as it is completely uncertified, without any assurance of its quality whatsoever. |
Oh, and if you don’t believe me on people buying and not using Pilot Awares, one has just come up for sale on the internet https://afors.com/aircraftView/43491 Bought a year or so back, never really used much as had no where to put it in flight. Only used a handful of times. Licence has expired now (£12 to renew) so instead being sat on a shelf some else can use. |
Thanks for all that gen.
And yes - having fitted it into our shareoplane, it is possible to fit it neatly, but is most certainly not designed for elegance. G |
Originally Posted by Genghis the Engineer
(Post 10169096)
Thanks for all that gen.
And yes - having fitted it into our shareoplane, it is possible to fit it neatly, but is most certainly not designed for elegance. G I suspect that will also be another Achilles Heel for this equipment. Some Light Aircraft pilots just fly the aircraf. Filling up with fuel, checking the oil level and cleaning the bugs off are as engineering focussed they get. |
Genghis
I am the Manager of the Kids of The Magenta Line. Map scale at 180Nm and the righthand windows full of checklists and highwizz west so no sun glares at the multiple phones and pads in use. The tendency to rely on electronics is scary, and the knowledge of limitations and practical use is not good. And the old WX radar they know nothing about, specially how to verify it with the fact ! ie OUTSIDE, big picture. BTW, I love the Hammer diagram, neat! Regards Cpt B |
Originally Posted by BEagle
(Post 10167360)
PliotAware will eventually become the conspicuity Betamax. It uses unlicensed frequencies so will never be certifiable.
... When I reviewed a number of conspicuity devices a year or so ago, the only one which was of any use was the Trig device which didn't need a display - and gave only genuine collision warnings. I was quite shocked at the 'panel gazing' of many of the GA pilots involved - VFR implies L00KOUT, not staring at some iToy! I agree with your comments regarding not staring at an iToy, hence I was pleased to read the following article on CHIRP, whereby a PilotAware user was able to avoid a sticky situation using his 'amateurish unlicensed dogs dinner of a toy, Lashed up in a shed' (search PilotAware Rosetta to see what this really looks like) If you want to read a genuine article by real users, go to page 4 Situational Awareness, no staring at iToys involved in this article http://www.chirp.co.uk/upload/docs/G...20Version).pdf Normal service is now resumed - please return to bashing PilotAware .... |
PilotAware, otherwise known as 'Explosion in Maplins'...…
If not the Betmax, then perhaps the 8-track or Elcaset? |
Originally Posted by BEagle
(Post 10172507)
PilotAware, otherwise known as 'Explosion in Maplins'...…
If not the Betmax, then perhaps the 8-track or Elcaset? |
I read the article Leemoore1966 and I immediately thought that all the Go Pros, Pilotaware, tablet, wires, cables, batteries, antennae and plugging into the aircraft audio may have led to the pilot being distracted in the first place. When I have a look at some of the General Aviation posts on FaceBook I am aghast at the amount of fiddling with gadgetry in flight that would get you 6 points and a £200 fine in a car! However, going back to Genghis’s original post, as we fly our aircraft globally then we need to have detection capabilities of international standards and not a proprietary standard like Pilotaware. FLARM is bad enough, but as it is mandated in several countries and strongly encouraged in others for gliders, that are notoriously hard to see, then it is worth it. In my humble opinion introducing another proprietary system at a low cost is counter to creating a safe environment as it just dilutes the chances of getting a detection of it by another system. 1090 Mhz mode 1, 2, 3 and 4 with C and ADS-B is already out there in use by the military and civilian operators, so why introduce something else? |
Originally Posted by handleturning
(Post 10167378)
This is the problem. The glider community tend to swear by FLARM and generally shout about it long and hard if you ever get into a discussion on such matters. An incomplete picture is more dangerous than none at all, particularly if used by low hours pilots without the experience to back it up. Understand Benson and Linton have FLARM displays in the Twr (but cannot use them for controlling), which raises some very interesting HF questions.
Can also understand Benson 'having a Flarm display' given it was from Benson an air experience flight departed that ended in tragedy for the two occupants, though IMHO it was completely avoidable without any sort of electronic conspicuity device. |
Originally Posted by 2 TWU
(Post 10168504)
Re the Tucano, don't know what FLARM is but I was flying the machine when TCAS was fitted. TCAS was, and presumably still is, a great back up but not a replacement for proper lookout.
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Cats 5 - appreciate the benefit that FLARM brings to the glider community in terms of not false alarming when thermalling. However, the continuing refusal of the glider community to fit transponders does give the rest of us a real problem.
Frankly, modern gliders significantly out perform legacy bits of kit. Having the performance to add a little bit of weight (Trig make transponders marketed as light enough for paragliders for crying out loud!) means, imho, the glider community should step up to the plate and add the same conspicuity measures the rest of the world are using, so we can see them and avoid them, and ATC can reliably monitor them using SSR. Doing so on a voluntary basis will prevent the need for the CAA to mandate their carriage. Imho though the old argument of weight/power no longer holds water due to a combination of performance of gliders and size/weight of modern transponders (and heaven forbid, two way radios....) |
Originally Posted by pba_target
(Post 10173374)
Cats 5 - appreciate the benefit that FLARM brings to the glider community in terms of not false alarming when thermalling. However, the continuing refusal of the glider community to fit transponders does give the rest of us a real problem.
Frankly, modern gliders significantly out perform legacy bits of kit. Having the performance to add a little bit of weight (Trig make transponders marketed as light enough for paragliders for crying out loud!) means, imho, the glider community should step up to the plate and add the same conspicuity measures the rest of the world are using, so we can see them and avoid them, and ATC can reliably monitor them using SSR. Doing so on a voluntary basis will prevent the need for the CAA to mandate their carriage. Imho though the old argument of weight/power no longer holds water due to a combination of performance of gliders and size/weight of modern transponders (and heaven forbid, two way radios....) The few people who have brought brand spanking new gliders have had transponders fitted, but then what's £2k when you are spending well over £100k? A low power transponder was promised (can't remember who by) but has yet to appear. Also most of us are not all flying the latest and greatest - I know someone doing great flights in a glider built in 1968. He has recorded flights taking over 7 hours this year as have several people from other clubs. Fitting any sort of transponder may well cost him more than his whole glider is worth. Remember that by a large we fly the best, most expensive glider we can afford. |
Surely power available is merely a function of the weight of the batteries carried? Appreciate if you're going for ultra long endurance flying this might be an issue but the reality of a few hours airborne isn't that 8 HR epic power requirement?
I do also appreciate that such things cost money, and (particularly at the glider end of the market) a lot of people are right up against what they can afford as a hobby. However, for example, in a similar way to other mandated bits of kit (appreciate new radios were less expensive) given plenty of notice (say a 2025 cutoff) then most people should be able to afford the investment. Where UAVs stand in all of this, buggered if I know. I genuinely don't think there's a practical solution to the risk of mil low flying having a mid air with a UAV. The only practical solution I can see is to make commercial operations notam'd and make mil aircraft sufficiently robust that a collision with anything sub-commercial is unlikely to be catastrophic. |
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