£1m military drone crashed in Wales after crew disabled anti-crash systems – report A £1m British Army Watchkeeper drone had to be scrapped after crashing at an airfield in Wales when the ex-RAF officer piloting it disabled the unmanned aerial vehicle's anti-crash systems. Although the official main cause of the accident was given as the automated Vehicle Management System Computer functioning “as designed …
"There was no suggestion in the report that the pilot was culpable for the drone's crash."
First time in history a "pilot" was not held accountable for a crashed vessel under his command after giving specific orders overriding safety protocols. He must be a son of a serving member of Parliament or something. .
As the article explained in length: leaving crash protection on would have resulted in drone doing another fly-around. Probably in endless loop, until growing winds shred it apart or fuel runs out.
And then, after overriding the fly-around protocol, another automagical feature kicked in and pressed the nose down. Right into the tarmac.
So in this situation, about the only way to salvage the drone would have been to disable all "idiot-proofing controls" and land with manual controls. Which it didn't have.
"As the article explained in length: leaving crash protection on would have resulted in drone doing another fly-around."
The _CORRECT_ protocol for ground conditions that your aircraft can't handle is to divert to another landing site. This applies whether the pilot is human of a computer.
The salient point is that the "pilot" is Ex-RAF.
This is a good example of why airlines no longer hire ex-military pilots(*). They consistently ignore safety rules and press on regardless.
It was known more than 5 years ago that US Army drones have a far lower crash rate on landing (it's almost zero) than USAF ones - and that's specifically because disabling the anti-crash systems or attempting to manually land a drone is a disciplinary matter in the US Army
(*) At least not without forcing them to go through civil flight school to get their bad habits knocked out.
> Is that this drone was of a horrible design.
Pretty much my takeaway as well.
> if Master Override is activated and one of the altimeters is malfunctioning, the Watchkeeper opens up its “ground touch” window from 1m sensed altitude to 20m sensed altitude. In other words, the drone might decide it has landed even when it is still 65 feet up.
Clearly whoever designed this was trying to solve a specific issue they predicted might happen, but didn't give enough consideration to what the actual ramifications might be
From the El Reg article, it looks to me like the pilots were trying to work around know problems with the automatic systems.
Hint: If you have an automatic system that you have to regularly override because the automatic system can't cope with a situation, then your automatic system might need revising!
It's worse than that, it was the people who make the sodding thing doing it but will they revise it, nooooo, not unless MoD stump up more money to fix something that should have worked in the first place. Don't get me started on the stupidity of using a LASER altimeter to judge landing height...
"Don't get me started on the stupidity of using a LASER altimeter to judge landing height..."
I think it depends upon how the laser altimeter is implemented. If the system just uses a single laser, in radar mode i.e. just relying upon the timing of returns from a single sensor stream, I can see how it might be degraded in the rain due to scattering and false returns, both from the ground and intervening raindrops. But that's foreseeable, so I'd expect them to use multiple beams in a combined direct/convergence scheme.
Such a scheme would split the initial single beam from the laser generator into five (or more) individual beams that would then be routed along fibre to the 'corners' and 'center' of the aircraft. Each of these sub-beams would then be split into a further sub-pair, with one beam in each sub-pair being used for direct measuring and comparison for consensus voting, whilst the other beam of each sub-pair would be directed to converge with each other, along the lines of the light system used by the Dambusters to ensure that they were at the correct AGL for the bouncing bombs.
Not really rocket science, or terribly expensive to implement.
'I think it depends upon how the laser altimeter is implemented.'
I'm 99.99% sure your idea is better than the one Thales have actually put on the aircraft, if only because there was an almost identical crash at Boscombe Down in similar conditions. Accident report for that one isn't out yet though as far as I know.
"... the stupidity of using a LASER altimeter to judge landing height" especially when it doesn't work too well with wet runways. AFAIK it rains more than a lot in the Aberpoth area - I've been there.
Things were much simpler in my youf, the drone that I worked on (to use the modern parlance) used a parachute when returning to terra firma. The parachute worked well, most of the time it worked well. La plus ca change la plus c'est la meme chose.
If your system like the one here in the States, the contractor built it to MoD (DoD in the States) specifications. It's also possible they tried to talk the MoD into something a bit different and were turned down. Government procurement seldom involves rational thought by the procurement types.
So true...
With 4 different equipments to retrieve the altitude, the system could sort the malfunctioning ones is a lot of cases. (3vs1 is trivial, 2vs1+1 might be manageable as well)
And for the landing detection : use Weight on Wheel instead of (or, better, in addition of) a fancy vertical speed detection! As even big commercial airliners get some trouble with air turbulence, no wonder a flimsy tiny drone (especially with the ground effect) get even bigger effects...
'Surely the "ultimate" landing confirmation sensor and far better than assuming you might be on the ground when possibly still 65' up in the air and nosing down to "make sure".'
No, I gather that the the nose down operation was to provide additional friction to improve braking*, not to "make sure" the drone had landed. It was applied after the drone was assumed to have landed.
*... Or more likely it's using the elevator for air resistance, to apply the equivalent of additional flaps. The article isn't clear on that and I don't actually know much on the subject.
Pitot Tube barometric pressure - I thought the pitot was specifically dynamic pressure, and you'd use the difference between it and the static (barometric) pressure to calculate airspeed. Always thought barometric pressure is from a ideways-facing sensor specifically to avoid dynamic pressure. Am I confused, or the author?
> I thought the pitot was specifically dynamic pressure, and you'd use the difference between it and the static (barometric) pressure to calculate airspeed
> Am I confused, or the author?
The author. You are entirely correct.
Also from the article:
"The Watchkeeper has four ways of determining altitude: barometric altitude, from the pitot tube; GPS altitude from its location unit; radar altitude, from the Watchkeeper system's ground radar unit; and its on-board laser altimeters"
Of those:
- The pitot, as explained above, is used to derive indicated airspeed.
- Barometric altitude (i.e., altitude on a barometric datum) is provided by the altimeters and measured at one or more static ports, so called because they are kept, within practical limits, out of the aircraft's slipstream, typically on the sides of the fuselage.
- GPS provides ellipsoidal altitude, from which geoidal altitude may be derived via a mathematical model. This bears no relation to barometric altitude other than in a very approximative way.
- Radar altimeters, despite their name, do not provide altitude information at all. They provide height information, which in aviation means how far you are off the ground, while altitude is how far you are from a datum, usually an isobaric surface.
- Laser altimeters, I am not familiar with, not being a drone pilot and that system not being present in the civilian types I'm familiar with. If the description from the journalist is correct (and at this point, that's quite an assumption), they appear to be analogous to radar altimeters, although they could also be LIDAR units as found in other autonomous vehicles, which serve a different purpose.
Right - the static port reports the current pressure altitude, which is compared to the dynamic pressure from the pitot tube. By itself, the static port is sufficient for pressure altitude, which needs a correction to account for surface pressure altitude in order to determine an actual altitude measurement.
The author is not confused; without the static port the pitot tube is inconclusive about the dynamic pressure. It's just a contraction of pitot-static tube that makes it unclear.
" Unlike other drones, such as the MQ-9 Reaper, the Watchkeeper cannot be flown manually"
But apparently it can be crashed manually?
" the crew selected Master Override (MO) in the hope they could get it back on the ground as quickly as possible."
Can you get on the ground any faster than crashing?
@AC - 'It was just more "in" the ground than "on"'
Well, no, "no damage was caused, other than to the drone itself", so the very expensive, military-grade concrete runway was completely unscathed by the incident.
Continuing this analysis, "Nobody was injured", so, on the basis that any landing you can walk away from is a good one, this was a good landing. They got the drone down, as fast as possible, without damaging anything else, and walked away.
Many years ago, I recall reading that one of the problems with automation was the insistence of "experts" that they "could do a better job". I'm pretty certain that this resulted in at least one system with a "manual override" that did nothing apart from power a light which said "manual override".
The recent Tesla crash, and future shape of driverless cars are in the mix here.
And a more recent - but very real - phenomenon is the rise of the "I know best in the face of OVERWHELMING evidence to the contrary". (In a recent interview, the comedian Nish Kumar was accused of saying something in a show at the Comedy Store. Apparently the Comedy Store records all performers, and Nish was able to *prove* he did not say what he was accused of. To which the guy complaining said "I know what I know" - i.e. fuck facts).
Well in this case, the highly trained operators knew they knew best - or rather, they knew of limitations and some 'known issues' with the automated system.
The Tesla crash was probably caused by its user not using it as intended - i.e, it was designed to supplement and not replace his control. However, there is a school of thought, as cited by Volvo, that this 'half-way house' approach is potentially dangerous, since human nature is to lose concentration at times.
However, there is a school of thought, as cited by Volvo, that this 'half-way house' approach is potentially dangerous, since human nature is to lose concentration at times.
Other experiments have shown that even when machines are blatantly wrong, humans are very reluctant to take over.
"Well in this case, the highly trained operators knew they knew best - or rather, they knew of limitations and some 'known issues' with the automated system."
And yet:
1: Knowing that bad weather was on its way in during a training mission, They didn't abort the training mission to get back to base before that inclement weather started closing in on the airfield.
2: When they finally did return the drone to airfield - and knowing that inclement weather _was_ closing in and that the ground conditions were already at or beyond the limit for the drone, they decided to try and land it anyway instead of diverting to another base and/or retreating to a safe distance whilst the front passed over.(*)
3: Having disabled the automatics they didn't warn the airfield that they were attempting a risky landing procedure, nor did they station anyone to watch it, so confident they were in their flying abilities.
This is classic CFIT(**) material and everyone involved should have the cost of the lesson deducted from their salaries.
(*) This kind of gung-ho attitude to flying is why civil operators don't like military flyboys. It's worth noting that whilst civil aviation has an exemplary safety record, general aviation is about as safe as riding a motorbike and non-combat military aviation is several factors worse than that (it's not just fighter pilots. The crash rate of military transports and of ex-transport military pilots in civil roles is significantly higher than civil-trained pilots and the single biggest contribution to improvements in civil air safety was to stop hiring them when they finished their military career.)
(**) Controlled Flight Into Terrain - the most common kind of aircrash in civil aviation until "human factors" became a large part of the training. ALWAYS concentrate on flying the bloody aircraft, then deal with any other problem, _before_ trying to land it.
Yup.
And this became AVIATE, NAVIGATE, COMMUNICATE when an emergency happens. Basically, fsck the automatics - keep straight and level at a speed above stall, then make sure you're not about to hit something big and rocky, then - and only then - tell world +dog what you're doing.
The Air France flight spending a long time flying into the Atlantic was absolutely unforgivable. Excuses were made, but it was 100% pilot (culture) error.
But with these drones it seems maybe they should only fly on nice sunny days.
Apparently the Comedy Store records all performers, and Nish was able to *prove* he did not say what he was accused of. To which the guy complaining said "I know what I know" - i.e. fuck facts [...]
"Fuck facts", the credo of the average Trump supporter.
There's a good book on how humans lie to themselves about what they've experienced, even when shown evidence to the contrary. It's called 'The Invisible Gorilla' and I'd recommend reading it if only because of the section on texting and driving.
As a counter to the Trump supporters remember Hillary insisted she'd come under sniper fire when landing in Bosnia.
> Apparently the Comedy Store records all performers, and Nish was able to *prove* he did not say what he was accused of. To which the guy complaining said "I know what I know" - i.e. fuck facts [...]
> "Fuck facts", the credo of the average Trump supporter.
Yeah... The Trump supporters don't have a monopoly on that. It applies equally to Democrats, and a wide variety of religious supporters, as well all the detractors. Basically, it is the credo of The Fanatic.
Fanatic: One who redoubles their efforts even though their aims have been forgotten.
The guy accusing Nish wasn't a flat-young-earth-no-moon-landing-oswald-didn't-do-it-alone-creationist, was he? They know what they know too. Which is 3/5 of 5/8 of fusk all. Problem with creationists is that they don't use the brains their god apparently gave them.
And yes, a French Israeli would make even an entitled little minor Saudi royal family sprog living in London feel inadequate! (And I can't wait to see one of those little shits declared PNG.)
Perhaps we should let Elon Musk have a go at designing these drones.
"Lessons from this accident are already being taken forward that will improve safety of the Watchkeeper UAV"
Like... actually sensing if it's touched the ground with some sort of wheeled mechanical undercarriage which can tell when it's bearing weight or whether both the undercarriage and drone have been jostled by a gust of wind.
Millions of pounds of hi tech equipment destroyed for want of a £1 microswitch.somewhere between the landing wheels and the body of the plane (doesn't even need to be load-bearing in any way, literally just a "click" when the wheels / landing gear / pedestal it sits on or whatever it has actually starts to take the weight of the plane rather than merely being dragged underneath it). Or a pressure sensor. Or even - shock, horror - when it feels the wheels start turning under roughly the same speed as it's forward motion...
That was my thought as well, although the £1 switch needs to be paired up with some wires and a bunch of code, and then tested, so it's not as cheap as all that.
(And maybe a sensor on each wheel would be better, if just one tripped on it's own then either only one wheel is down, or you have a malfunction)
The problem with weight on wheels switches is that they're not that reliable, there was a problem on the RN Lynx when they added one during an upgrade and then because it failed so often they gave the crew a switch to manually set instead. Don't forget it can fail on take-off as well which opens up all kinds of interesting scenarios.
"The problem with weight on wheels switches is that they're not that reliable..."
I think you'd be right if the only choice was a mechanical switch but these days it would be trivial to fit multiple induction sensors to each strut - something based on the R.P.M. sensors ubiquitously fitted to all but the very cheapest P.C. cooling fans would do the job pretty well.
"Millions of pounds of hi tech equipment destroyed for want of a £1 microswitch.somewhere between the landing wheels and the body of the plane "
I recall when somebody wanted to add what started as a £1 potentiometer to a piece of military hardware. By the time it had been fully hardened, it cost £4000 exclusive of development costs.
> Millions of pounds of hi tech equipment destroyed for want of a £1 microswitch.
By the time it's been rated "aviation safe" it'll cost much more than £1. I remember seeing £20 spanners coming into the aviation workshop still carrying a price tag that indicated they'd cost 10x as much. Partly because Government contract, partly because they'd been rated as OK for use on aircraft.
So that £1 microswitch may well cost hundreds, if not thousands from the supplier
Nah. They've been used for decades on commercial passenger aircraft. No development costs for the switches as they are already certified. And nowhere near hundred of pounds, or dollars, but yes they are probably in the $50 range for something *almost* identical to what you can get at a hobby shop.
Just a matter of adding them & coding for the input.
Much of the extra cost is for traceability. If a 50c screw breaks in your car, it probably won't matter. If one breaks on a plane it can kill hundreds of people. EVERYTHING is traceable back to the manufacturing batch it came from, so that if a failure is traced to a part, the parts from that batch can, in theory, be pulled off every aircraft it is used on across the world. For a commercial airline, every job you do has to be signed off & countersigned that it has been completed to the manufacturers specs, quoting manual number, revision, date and parts used, (with batch number). If something happens, it can be traced to who & what. And if it is YOU that caused it...
There's a reason we called finishing a job, "Signing your life away."
Nah, it was chopped out to save a few hundred million. After all, the bad guys are all in the desert where it don't rain now does it? Balls. It snows in Iraq and Syria.
Anyway, what idiot decided that a laser altimiter was a good idea. So what happens when the bad guys fire a laser at the drone? What then?
This whole program seems to be a complete TITSUP from start to finish.
Now I never knew that it snowed balls in Iraq and Syria.
Would that negate the need for a goolie chit?
It crashed TITSUP, you say - One is intrigued as to how that anatomical position relates to the crash aspect of drone aircraft ...
Enquiring Minds etc etc ... This is a scientific publication after all - even on a friday
Thanks - its the one with the damp pitot tube in the top pocket
If it did save a few hundred million, then it looks like a wise choice.
They could operate these for 20+ years before the cost of a better system would make the upgrade would be worthwhile.
I'm not suggesting this was fully understood or considered by those making the purchasing decisions...
Wouldn't a simpler system that maybe measured the weight exerted on the landing gear be somewhat more of a safe way to tell if the thing is actually on the ground or not? Presumably the thing has wheels of some sort, and one would hope the downward pressure on them when it's on the deck would be somewhat more than when they're dangling below it whilst flying (or preparing to land if they're retractable).
Or is it the old scenario when people think multiple highly complicated systems must be better than one simple one? All 3 wheels bearing weight = drone on terra firma, and then set about stopping it.
Reminds me of a posting years ago on comp.risks (just typing that makes me feel nostaligic for the days of Usenet news!) of a test pilot in a new US "fly-by-wire" fighter jet who decided to find out what happend if he preseed the "retract undercarriage" button while stationary on the ground .... cue an update to the software ti add a "if (! load_on_undercarriage)" to the code that retracted the under carriage
Maybe, maybe not. I do know of someone who used to work in a garage as a mechanic. They manually pushed a car right up against a wall to make room for another job. On deciding to then get that first car back out, someone decided to start the engine. Being a Citroen BX with engine powered hydraulic suspension, the car immediately lifted up a few inches, crumpling the bonnet under the sink on the wall.
cue an update to the software ti add a "if (! load_on_undercarriage)" to the code that retracted the under carriage
Relying on that is specifically warned against...
Some pilots were in the habit of pre-selecting gear up, then taking off. As the aircraft leaves the ground, the wheels are retracted of their own accord. And it all looks very cool.
And then you hit a bump just before takeoff, the load goes light, and the wheels are retracted long before rotate speed...
Vic.
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I believe ILS wasn't part of the spec because it's supposed to be capable of operation from austere strips so the added weight* wouldn't be worth the few times it'd get used.
I believe the problem with GPS is that the altitude output is the least accurate reading so it wouldn't be reliable enough on its own to get you back down, although the recovery is mainly done by GPS the final few feet need something more accurate to avoid flaring to late or as in this case too early. Personally I'd suggest making the undercarriage stronger and allowing it to do a no flare landing like a carrier aircraft.
*It's really quite small.
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'I assume you have never been on an aircraft carrier in a storm, it pitches, rolls and yaws rather well.'
Yes, yes I have, doesn't affect how the aircraft land though, constant attitude all the way to touch down rather than flaring a few feet off the runway. If Watchkeeper did that you wouldn't need a precision altimeter to decide when to flare, and then get it wrong and plummet 60'.
Incidentally it's an Army programme not an RAF one. And not even the Air Corps, it's the Royal Artillery.
"Incidentally it's an Army programme not an RAF one. And not even the Air Corps, it's the Royal Artillery."
Well, speaking as an ex-artilleryman, the artillery's core competence is turning all kinds of things into rubble. (Including from time to time their own observers, but that's another story.)
"I assume you have never been on an aircraft carrier in a storm, it pitches, rolls and yaws rather well."
<snip>
I fast roped onto the Clemenceau many times. One false move and you had either broken legs or hip joints embedded into your rib cage.
I take it that this is a surveilance drone? I could not imagine the amount of way points needed to accurately track and destroy a Hilux full of AK carrying wedding guests and assorted civvies.
It seems the Watchkeeper (and its predecessor, the Elbit Hermes) have being performing better in Afghanistan than in Wales! Considering how the radar added to the Watchkeeper is designed to peek through sandstorms, it makes you realise just how inhospitable a place Wales is.
Surely the simplest solution would just to have a parachute system for getting the drone down when all else fails? It would probably take up a fair chunk of internal space but is a well-developed and pretty cheap solution Even if the drone parachuted into the rough it would probably take less damage than a twenty-foot nosedive into the runway.
I am pretty sure there is a rake of similar systems on commercial airliners that could be simply adapted to work on this drone.
Airliners, amongst a load of other landing fault prevention gear have a thing called a squat switch that tells it when each oleo has compressed enough to indicate having landed, used along with the altitude sensors it would perhaps let the drone know that it is not on the ground.
Of course if one crashes you get to sell a replacement.
Then maybe the taxpayer should look to acquire these on an "as a service" basis, ie drones as a service, sold at a fixed cost per flying hour, supplier picks up the underlying costs and risks.
It's the way RR sell their engines for large civil aircraft, apparently.
If the thing can't tell the difference between 20m and 1m in "MO" mode, why have it command a "pitch down"? Why not enter some sort of "glide mode"? Surely coasting off the end of the runway into gravel or sand is better then going nose-first into the runway from 20m in the air?
And if they just want a ridiculous number of sensors, why not also install ultra-sonic range finders? Not as a "what is my total distance" but as "is there 'something' in range"? Narrow the scope from 20m to a few meters, save a few million in crashed drones.
It does show that you can't mitigate against stupidity.
Once many moons ago I saw what happened when a supposedly intelligent lad took a jam tin full of coals into his VAB (French armoured vehicle). Sealed the vehicle totally and as he slept the coals consumed the oxygen and he did not wake up. It was a bugger getting the vacuum broken on the doors next morning.
..."including its barometric pitot tube, which indicates height.."
Aren't pitot tubes normally used for sensing air speed, in combination with a static port, for sensing barometric pressure? The pressure at the static port gives you an indication of altitude. The difference between this pressure and the pressure at the pitot tube tells you something about airspeed.
"Crucially, if Master Override is activated and one of the altimeters is malfunctioning, the Watchkeeper opens up its “ground touch” window from 1m sensed altitude to 20m sensed altitude. In other words, the drone might decide it has landed even when it is still 65 feet up. Once the on-board computer decides the Watchkeeper has made contact with terra firma, it is programmed to select full downwards pitch"
I'd love to see the video of the "landing"
...But I have to commend the El Reg commentards for yet again promoting a lively and very informative conversation.
Vaguely recalling an article from a few days (weeks?) ago re ad blocking and paying for quality content, I would gladly offer a monthly subscription to browse the comments on this site as they offer the most informed and balanced resource I've come across for tech news.
Thanks everyone, and keep up this awesome community. I would post more often, but as a jack of all trades I feel like I benefit far more from the insight of all the experts out there so keep quiet, but huge thanks to you guys (and girls)!
Perhaps the best idea would be to stop using "drones" and go back to using "queen bees". Queen Bees used a trailing rope with a weight on the end to detect altitude, which then closed the throttle and pulled back the stick. Of course it helped that they (usually) landed on water which tends to have fewer high obstructions than the land.
Nosing down generally picks up speed both downward and forward, recognized by noted Brit AC designer I. Newton. Pilots slow down AC by applying back pressure. Once AC is actually on ground (by checking the WoW switches (aka "Squat switches), then slow down with hard braking, forward stick, flaps up, and if configured deploy slats and tail parachute.
GPS data in wet Wales becomes unreliable because of change in Speed of Light as encountered on the different paths from the 4 or more satellites needed. And you may have to up the computation rate of the GPS package to deal with an AC moving at 120+ FPS (30MPH=44 FPS.)
Has *anyone* considered that crashing this drone *on the runway* may have been the preferred option
- as opposed to having it crash *elsewhere*, e.g. into considerably more expensive military hardware
- or, perish the thought, civilian wetware. As duly noted, the runway was quickly back in operation after the application of a broom & shovel...
> they tend to have lots of fire engines
Civilian aerodromes open for public transport have a "fire category", which basically denotes the largest aircraft they can serve. I do not recall the categories and their requirements from memory, but at many of the airports that I used to fly to, you wouldn't be talking of fire engines in the plural. And by the way, the last thing you want is one of those places where there is a dedicated airport brigade, as opposed to being part of a larger organisation, as they tend to be rather short of operational experience.
Civilian aerodromes not open for public transport do not require any form of fire fighting equipment (though other regulations, including local ordinances, may apply).
Military aerodromes, I have no idea.
... is the very idea of pushing your nose down to slow down. To me as a (private) pilot that sounds like a massively stupid idea and is something you never do in an aircraft for many reasons. One is that the nose wheel is only designed to carry a very small part of the weight of the aircraft and you are supposed to take off even that small weight whenever you can (by pulling the stick). Another is that on a tricycle, moving the weight from the main gear towards the nose wheel is not good for steering stability. And finally it achieves nothing in the way of slowing you down apart from the small drag caused by the deflected elevator and is in fact the opposite of what you do in aerodynamic braking.
Of course the makers of the drone know all this. I suspect the real reason for pushing after touchdown is simply to make sure the thing stays on the ground despite the excess airspeed the thing probably lands with.
Most GA craft have the prop on the nose. One of the strongest disincentives to nosing down is that it can (and frequently does) lead to prop strike - and as mentioned wheelbarrowing is risky (there's a lot of mass in the engine/prop)
This bird has the majority of the weight to the rear (engine and prop), so nosing down isn't such a bad thing, but it would still lift weight off the main gear and as such render the brakes less effective.
> the very idea of pushing your nose down to slow down. To me as a (private) pilot that sounds like a massively stupid idea and is something you never do in an aircraft for many reasons
This bears zero relation to the case at hand, but FYI, the touchdown procedure on larger aircraft mandates the application of forward stick pressure upon landing. This is primarily to counteract the effect of lift (now in ground effect) and the pitch-up caused by the thrust reversers. Airliners fly more like gliders than C172s and (like gliders) they just don't want to land and stay on the ground. In comparison, a 172 is like flying a sack of potatoes.
But even on a small aircraft, taxing or rolling off after landing requires forward stick pressure in the event of a tailwind (and at certain places, notably altiports, landing with a tailwind is a requirement in order to be able to take off afterwards).
With all due respect, just because you do not know why something is done, it does not mean it is a "stupid" idea. All the more so when you are reading a hearsay description of an event penned by a journalist with no aviation background for a public with no aviation background--this is to be taken as entertainment reading only.
Very simple way to land a smaller plane (RC, Drone Etc) in adverse weather.
Set attitude at level and airspeed at a rate that will result in a shallow decent. keep everything level and aligned with runway until a sudden decrease in sink rate is detected (i.e. ground contact.)
upon ground contact, engine to idle and brakes on. if sink rate increases again (like in a false contact) return engine power and brakes off. this way the plane comes down to a 3 point landing, and when it is on the ground the controls keep it level and straight until it stops. might run out a bit longer then their current landings and it may result in a few hard contacts but it should not result in a CFIT like this. (Controlled Flight Into Terrain i.e.. diving straight into the runway.)
Have this as the override instead of just shutting off the crash prevention.
Seems to me some technology hasn't changed much in 35+ years.
The Midge (Canadair USD-501) used by the army for surveillance in the 70's and 80's (even the first Gulf war) were programmed using waypoints, although these couldn't be changed after launch.
This returned to terra firma via parachute normally quite successfully but not always in one bit - I have pictures to show the after effects.
These were designed with replaceable nose cones etc. to absorb landing damage, something I'm sure the Watchkeeper doesn't as it's designed to land on runways.
".... I'm sure the Watchkeeper doesn't....." The Watchkeeper design has two under-fuselage bumps, one for the camera and one for the very expensive radar. Even dropping it on its nose, it will then likely fall onto its belly and smash the radar, unless they can find a way to make it drop onto its back. A belly-mounted parachute might work - engine off, pitch nose down, trigger the 'chute and the aircraft then flips inverted before landing on its back.
> Your money mind, but only money!
Apocryphal story:
Military plane at a civilian airport, number one for departure, doing lengthy pre-departure checks and causing a bit of a hold-up. Eventually the controller gets exasperated and goes:
"Flight XYZ, how much longer before ready?"
"Another 5-10 minutes, XYZ"
"Well, the people behind you are paying for their fuel, you know?"
"Affirm. They're paying for ours too."
Its a big RC airplane and as anyone who has built and flown RC will tell you " if you don't want to break it don't build it in the first place!"
No matter how clever you make the device humans will screw it up, the difference between ground speed and air speed is hard to judge when the airplane in the air and your on the ground.
Landings are a prime fail time for RC airplanes look at youtube.
"If the readings from these four sources disagree while the drone is landing, it is programmed to automatically abort the landing"
I can see this meaning drones never coming back down till they run out of fuel. I have four ways of determinimg who is logged onto a win 7 pc , but the chances of all 4 methods agreeing are slim . I have to "take an average"
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