gallois wrote:
GBAS is much cheaper but then again for the equivalent of CAT3 ops you would probably also need the back up autopilot as carried on CAT aircraft that use CAT3.
It is much cheaper for the airport but more expensive for the aircraft, I’m not aware of any non-transport category aircraft with GBAS capabilities. Not for GA!
It is also difficult for the crew to manouver along the runway and onto the taxiway when they can’t even see the runway markings.
Most airline LVP SOP require around 70 RVR for taxying
One thing to remember for Cat III ops is that not only does it require crew, aircraft, and airport to be qualified (trained/equipped/certified), but the aircraft is equipped with dual autopilots, and potent de-/anti ice systems.
Not sure how these requirements will be met for a SEP, the more so since Cat III ops is usually performed in icing conditions…
@snoopy @A_and_C @chrisparker @Pirho (and countless others)
Maybe we can get some input from airline pilots?
One Easyjet colleague tells me every landing (except hand flown ones to some unusual places) is set up for CAT3 initially. Yes they cannot taxi in zero-zero in most places. But autoland is crucial and without it the present day airline business (wx cancel rate < 0.1%) collapses. LPV does not fit into this at all, most big jets around Europe cannot fly LPV, and a large % of 3rd World stuff, especially cargo, is firmly ILS and will be ILS for many decades.
Think about it: if LPV was relevant to airlines, they would be pushing for it, and they have clout, and money. We would be seeing some results – like the UK DfT paying off Brussels with a wad of €€€€€ to get the CYA “safety of life” bit of paper.
Whether every approach is set up as an autoland is largely a company SOP thing, perhaps type dependent too.
My previous employer never set up for autoland unless it was expected to be required. When so moved to my current employer, flying the same type, we set up everything for an autoland but disconnected it and landed manually every time unless conditions required the autoland. A few years ago this SOP changed and now we don’t set it up unless required.
We don’t gave a formal minimum vis for taxi.
I agree that autoland is important, but for what it’s worth, most of the value of it in my opinion is to facilitate legal dispatch as opposed to actually needed it to get in somewhere. In the last 5 years I think I have maybe had to autoland in anger twice.
LPV is I’m sure the future, but you probably don’t see airlines pushing for it because of the capability of so many in service aircraft. You have ILS which is proven and every commercial aircraft can do. LPV most still can’t, then there is the hurdle of approvals, and probably years and years and years of phased testing and trials to get minima down to what is current possible with ILS.
I wouldn’t refer to it as “autoland is deliberately set up for every approach”.
To explain,
for aircraft that are CAT III + autoland capable
one needs to distinguish between
- low vis CAT II/IIIA/IIIB autoland dictated by vis
and
- CAT I voluntary autoland.
E.g on the B777/787 a CAT 1 approach can be manual or autoland using ADCS LAND 3 (without LVP protections/sensitive areas).
The AFCS will use LAND 3 by default logic (irrespective of what condition the airport is in), and theoretically, if you wouldn’t touch it, would autoland. “It” doesn’t know if LVP are in force or not.
In practice this never happens, unless you specifically intend and brief a CAT I autoland and watch like a hawk to take over (or arrange it with ATC).
Now for a CATII/III low vis, there is more deliberate setup/SOP/callouts. This isn’t done for every approach, only for lowvis.
Not sure 100%, but IIRC we had to let the aircraft perform an aland once a week on the ARJ85/100 to retain the Cat IIIA status with its fail passive AP
Peter wrote:
One Easyjet colleague tells me every landing (except hand flown ones to some unusual places) is set up for CAT3 initially
That is not really correct. Yes, technically the aircraft is ready to perform a Cat III for every landing, assuming the airport is too. But basically an approach set-up/briefing is performed prior to the beginning of said approach, and the decision matrix usually given by the airport being in Lovis ops or not.
Airborne_Again wrote:
I guess it is theoretically possible to design an SBAS LNAV/VNAV
There is an EASA general approval to substitute an SBAS-aided GNSS for BaroVNAV in “EASA AMC 20-27 with CM-AS-002”. It must have been inherited into UK regulation on Brexit and unless overridden since then, should still be valid.
I have to add that cat3 also requires 2 working Radio altimeter (in additional to 2 APs and these working). I may be mistaken but to have autoland activated, bot PF PM have their avionics and set 2 AP ON to switch to autoland mode.
If not, it’s like another ILS/LPV approach, meaning AP will have to be disconnected at some point. And if ever AP is still on at the flare, plane will land hard and break anyway (fail passive). I don’t know if a A320 pilot ever let the throttle not fully back once; just to try if the “retard…. retard” will keep on endlessly… :D.
Peter wrote:
I doubt that since there is no “CAT3 LPV”, and airline ops without CAT3 are more or less totally unviable.
Not all airlines have CATIII approval or equipment, by far. E.g. Hop!, the regional airline subsidiary of Air France, emphatically does not. They are approved only to CAT I.
