Peter wrote:
Can’t see anyone posting that. Where is it?
Maybe it’s me who said that 
I don’t think you need AT to bring GA aircraft down to 100ft on “horizontal & vertical guidance”, no need for FADEC neither (you can do it with simple binary power controllers, LOP fuel flow table if you wish), then bellow 100ft, you flare power off (or idle setting or leaving a tiny power)
I don’t recall doing power for speed bellow & pitch for glide path bellow 100ft to hit an ILS Cat3C TDZ? I just make fully held off landing and my TDZ is random, this is unlike RyanAir “firm landings and positive impact” with 3D guidance until you lose teeth and they open their spoilers, they have to do it as the 737 needs to fit within some hot regional airports 2km LDA
On 2km runways, I can land a Mooney or Glider passing 140kts over threshold then idle power, the only time I ever needed to AT (or dynamically adjusting glider airbraks) was during “spot landing completions”, I think 50% power > 50ft and 0% power < 50ft with 2km LDA should do to land in any kind of wind conditions with pure “H & V guidance”
Me thinking one can flare their C172 power off with flaps, trim & rudder only !
“nobody needs auto land” ;-)
Can’t see anyone posting that. Where is it?
It’s a matter of what may be achievable. Otherwise one ends up arguing for auto brakes and auto taxi along taxiway markings, which obviously takes it into the realm of “will absolutely never happen”.
after 5 pages
Always interesting to note what pagesize setting people use This is post #45, so is on page 1 for me. Much faster to read.
Peter wrote:
I don’t think AT is absolutely necessary for a GA system
Peter wrote:
Also a total CAT3C mode is not required.
In a thread that should discuss what it takes to bring auto land to GA it is an interesting answer after 5 pages to state “nobody needs auto land” ;-)
It might well be that auto land (similar to CAPS, etc.) is of no big practical use in GA, but for some it would be a great peace of mind tool and therefore they might not need it (in a technical data driven sense) but might want it.
Peter wrote:
they might be 100m/100ft cloudbase,
The more practical application is not 100ft base but 100ft tops. Ground fog is preventing much more GA landings than low ceilings.
I don’t think AT is absolutely necessary for a GA system – the pilot is capable of controlling the airspeed, especially since he has nothing else to do
After all, we don’t have “full protections” elsewhere, even in FADEC installations. You still need to manage icing conditions (use alternate air, etc). In airline ops, money is no object and you need maximum automation because the ops are often de facto single pilot (with a 250hr RHS they really are single pilot).
Also a total CAT3C mode is not required. Most of the time when conditions are below minima, they might be 100m/100ft cloudbase, which is completely different and anybody who can fly could fly a normal ILS in that, on autopilot.
I don’t see how you want to bring down an airplane with less than binary power control when autoland can potentially be enabled when the engine runs on climb power. Unless you have a cooperating pilot who at least throttles to something like 50% power before he enables the system.
And while autothrottle is simple to do with FADEC it is not impossible to emulate one with ignition cutout or by manipulating ptch on an electrically controlled constant speed prop. Of course such a system would then only be used in a real emergency. Especially the ignition cutout method would probably bring a passenger close to a heart attack.
When it comes to breaking on the ground there are similar workarounds possible when we’re talking about emergency use only and accept a low speed crash just like we also do with CAPS. First of all with a runway in the 750m range you don’t need much braking at all on some grass runways the plane will even get stuck in the mud much earlier. Then again you can use a variable pitch prop for reverse thrust (unfortunately you need a method to apply full power otherwise not much use of that).
There are always exceptions, even in DA42 “you keep some power” bug you don’t fiddle with it up to the point that you need to auto-throttle
Keep some power & cut power is the same to me, it depends on your aircraft idle setting, it’s simple engineering and basic cable tension physics…
You can land C210 power off with smooth touchdown, it won’t be certified if that was not possible
I DO need to adjust power back and forth
Are you talking about approach? or flare?
I would be worried if you adjust power when flaring SEP up to point where you need an AT
For approach, down to 200ft can be done with H & V guidance on fixed throttle sitting, no AT technology is required, to keep 3D glide path all the way during your flare to touchdown you will need AT…
Ibra wrote:
In SEP, we usually cut throttle bellow 50ft
Not on every airplane. For example you land a C210 with some power, especially if nose-heavy. Also, at some point you’ll need to stop the engine. Autoland is pretty useless if you keep going off the runway at, say, 50 kts. Which, incidentally, brings us to the next issue: auto brakes.
Ibra wrote:
Why you need AT to auto-land? it’s only required if you are staying on 3deg glide path from 200ft to TDZ…In SEP, we usually cut throttle bellow 50ft (double deck bus height) or maybe leave a tiny bit in say DA42 (to void harsh prop breaking as props go on fine pitch), I don’t recall dynamically adjusting it from 200ft to TDZ, if fact I don’t ever recall touching down on same spot…
The only time I was fiddling with the throttle to land bellow 200ft agl was in flapped PA18-151, I once touchdown with 80% power (the whole approach is done in flare attitude and lot of power is used to smooth your ground impact and break RoD from slow speed)
@ibra, I’m not sure what you mean, but when I land the land I DO need to adjust power back and forth.
And if we are talking in context of fully automatic landing as per OP, then how could you possible maintain the right speed and angle without ever adjusting the power?!
This means the solution is not doable purely with H and V guidance
Why you need AT to auto-land? it’s only required if you are staying on 3deg glide path from 200ft to TDZ…
In SEP, we usually cut throttle bellow 50ft and start flaring without 3D guidance, what people call the double deck bus height (or maybe leave a tiny bit in say DA42 to void harsh prop breaking as the props go on fine pitch)
I don’t recall dynamically adjusting power bellow 200ft to TDZ to stay on Cat3C signal, if fact I don’t ever recall touching down on same spot, except on “spot landing” competitions
The only time I was fiddling with throttle bellow 200ft agl was in a flapped PA18-151, I once touchdown with near 80% power (whole approach is done in flare attitude and lot of power is used to smooth your ground impact and break RoD from approaching on very slow speeds, of course many do this is calm conditions and post it on YT)
I have not seen a zero/zero landing in bad weather using this STOL technique yet but I gather it’s possible with Synt-Vision in hardcore IMC, 300hp and fat wheels Super Cub: you keep you flight path vector on runway threshold with power while pulling to stall it with the yoke !
arj1 wrote:
In the UK in 2013 there was a case where a passenger had to be instructed on how to fly and land a small plane (pilot did not survive it – heart attack well before landing).
Same a few years ago in southern Germany. Pilot suffered in-flight heart attack. His daughter, who had been flying with him for some years so was familiar with the airplane but not a pilot, landed the airplane safely across the border in Austria. Sadly, the pilot had expired by then.
