Peter wrote:
If one was doing GA autoland, how would it be done? Any ideas?
How much change is acceptable in that thought experiment?
We could go with GLS systems – prototypes are OK up to CAT III.
Or ILS CAT III (need RADALT)
Or LPV?
The biggest obstacle here is Autothrottle, as soon as it is done, all is OK.
And the A/T is expensive – the cheapest I heard are supposed to cost tens of thousands.
If we are talking about the new implementations, then G3000 with FADEC (or single lever) and A/T would be an absolute minimum, but it costs a lot…
Not sure how it can be done on a non-business aviation fleet.
That’s an excellent point about the auto throttle.
In the piston world you can’t have AT, because there isn’t the climb perf. It would work partially with FADEC engines and would work with “three lever” stuff only in level flight or descent.
And any AT retrofit is always going to be a major job.
This means the solution is not doable purely with H and V guidance.
Peter wrote:
In the piston world you can’t have AT, because there isn’t the climb perf. It would work partially with FADEC engines and would work with “three lever” stuff only in level flight or descent.
The question is: will it work in new aircraft?
I’m just not aware of any currently produced piston a/c that is fitted with G2000/G3000 (there was Cessna TTx but no more).
Garmin people were talking for years about a cheaper A/T solutions, but nothing materialised yet. And again, which avionics suites it will work with?
As the cockpit door was locked, he had to break in by force which took some time.
If I remember a CRM recurrent where this was presented correctly, the cockpit door unlocked after the IDGs (electrical power) went offline (due to engine out after fuel starvation).
The greek F16s saw the FA and exchanged some hand singnals even (?!) and followed the 737 until impact (failed forced landing).
Autoland capable airplanes have 2 autopilots at least which output is compared until touch down, and could disengage if they disagree.
(What I remember from MCC stage). And once arriving at flare, the pitch is commanded from RA and not altimeter or GS/LOC anymore. I think it’s a very different logic from GA autopilots.
Last things I remember is that these autopilots are called « Fail safe », meaning that if autoland mode fails, it will still land hard but managable bu the plane, meaning that it will keep wings level and target a correct but hard VS until touchdown.
I don’t speak about autobrake and A/T another story…
Yes, either fail passive or fail operational
System Safety
Autoland systems are normally designated Fail Operational or Fail Passive.
A Fail Operational system must have at least two autopilots engaged for the approach. The failure of one autopilot will still allow an autoland to be carried out. This allows a “no decision height” approach to be conducted.
A Fail Passive system is normally associated with a single autopilot approach. In this case, failure of the autopilot will not result in any immediate deviation from the desired flight path; however, the pilot flying must immediately assume control of the aircraft and, unless he has sufficient visual reference to land, carry out a missed approach. The lowest allowable decision altitude (DA) for a fail passive system is normally 50’.
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.
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 !
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?!
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.
