Peter wrote:
Perhaps the main issue is that very few GFC500 owners know about this.
Then they don’t bother to read the very prominent limitations in the guidance material.
Quote1. Yes, very slowly…
2. Not much goes wrong with enroute nav
3. Much higher (even if very low in practice)
4. Hand flying, yes
1. really ? Quite a few – so the confidence in GPS reliability must be quite high
2. correct – but you – and ATC – are relying on it … and except during arrival in mountaineous terrain …
4. you can still fly in HDG and VS mode which is not bad at all
I think that UK LPV map is from Eurocontrol i.e. from 2120 not 2020 
UK is probably a little bit behind …
Peter wrote:
I think that UK LPV map is from Eurocontrol i.e. from 2120 not 2020
I guess that remains to be seen. Certainly the vast majority are yellow (planned) rather than green (operational). Quite a few in the southern half of the UK show a planned date of 2020/12/31 so we’ll know shortly if that is smoke and mirrors or not. Others are planned for 2021, 2022, 2023, or just “planned” which probably means after 2025 and don’t ask.
Sir_Percy wrote:
3. How is the probability of a GPS outage compared to a ILS outage ?
Police forces can, and will, jam GPS reception within a circle of a couple of miles, i.e. in case of drones. More likely, though, is an outage of one of the critical position sources inside the airplane. All in all I don’t care, how probable one or the other may be. I want to have full redundancy, and the GFC doesn’t offer it.
EuroFlyer wrote:
I want to have full redundancy, and the GFC doesn’t offer it.
Did you mean “I want to have full redundancy for coupled approaches, and the GFC500 doesn’t offer it.”?
The good thing is you can buy what you want – like the GFC 600.
Concerning redundancy – if you want full redundancy then you need dual AP with dual servos and dual NAV receivers – and you will still have a single ILS transmitter.
You have to look at it on a system level and on this level the GPS adds one more component in the chain which obviously increases the propabiltity of a failure. The question is how much and if you can deal with it. Obviously the certification authorities came to the conclusion that it is acceptable.
It would be interesting to see a comparison of the failure prob between the GFC and the legacy APs with their aged and low MTBF components.
People care about this GPS failure mode, but have no problems to fly with 20 or 30 year old servos where the failure can‘t even be properly detected and annunciated. Kind of weird for me …
Our planes are packed with single points of failure.
To me this one is acceptable, but fortunetly there is a choice for everyone
Before we get excited about “full AP redundancy against GPS outages”, in the strict sense, one has to keep in mind that they need to keep a standalone vacuum or electric AI/HSI that they can plug to the AP in APP mode, anything else will be mixing stuff to some extent…
I agree with Sir_Percy, I saw more worn servos issues or failed annunciations in legacy APs than issues from GPS loss in new APs
How often does the KI256 driving the autopilot fail – as opposed to the GPS – and how often have we witnessed forumites going up in arms about it with a similar righteous indignation? Such a fuss is made about a possible GPS outage you’d think they happen at least as often as vac pump failures.
