I press it when heading (usually in HDG mode) towards the LOC.
Then in intercepts the LOC and shows GS is awaited, then it intercepts the GS and there you go.
Any sort of auto intercept is a bit dodgy because you can have false localisers. These are well away from the real one; say 50 degrees off. But I’ve had it happen. So I set up the OBS mode to show a magenta line where the LOC is expected to be (OBS mode, plus the course pointer set to the LOC bearing) and then I can see where I am.
Then there is no LOC or GS. You fly it entirely in NAV mode and don’t touch anything (KLN94 and KFC225). APR is not used.
OK, I should have said LPV. Same question. There is a GS – albeit a synthetic one.
Peter wrote:
Then [GPS approach] there is no LOC or GS. You fly it entirely in NAV mode and don’t touch anything (KLN94 and KFC225). APR is not used.
Shouldn’t you use APR because of the added sensitivity of the CDI when flying an approach?
I don’t know the KFC225 logic for LPV. Do a search – multiple threads on the button sequence.
No; an IFR GPS auto selects 1nm FS in 30nm radius of the airport and then gradually reduces this to 0.3nm after the FAF. This is done in the GPS, not in the autopilot which has no idea where the airport is.
Peter wrote:
No; an IFR GPS auto selects 1nm FS in 30nm radius of the airport and then gradually reduces this to 0.3nm after the FAF. This is done in the GPS, not in the autopilot which has no idea where the airport is.
Exactly. That’s why I would expect you to use APR as the A/P has no means of automatically knowing that you have selected a navigation source which is more sensitive. The feedback loop in the A/P would need different parameters depending on the sensitivity of the CDI.
Actually an LPV (WAAS) acts as a funnel and narrows from 0.3 nm at FAF to around 350 feet at DA MApt
Having finally got my plane back, I tried this again yesterday. No luck. I was flying the RNP 15 at Perpignan LFMP, a very simple LNAV/VNAV approach. I was already using the AP in NAV/ALT mode. I pressed APR after the IAF and before the only IF. APR lit up on the AP. It turned onto the IF-FAF leg. I saw the GS come live and descend, but the AP flew right through it and the dot continued to descend. No GS annunciator came on. Needless to say I pressed the Big Red Button and hand flew the approach, although I was in VMC anyway.
Is anyone else flying a KFC225 with an RNP-capable navigator (GNSx30W, GTNx50)? And if so, can you get coupled approaches to work, and if so, how?
The manual is no help at all. It was written long before LPV or VNAV approaches existed, and talks only in terms of ILS and capturing the localizer.
In fact I wonder if this might not be the problem. When you’re flying with GPS, you never “capture” anything. The needle is always centered. Maybe the KFC225 needs to see the horizontal capture to get itself into the right mode to capture the vertical guidance?
Google didn’t come up with anything helpful. There are a couple of things on Beechtalk that look as though they might help, but you need to be a member and since I don’t own a Bonanza, I probably wouldn’t get accepted.
It works on the ILS but probably not on an RNP which is basically NAV mode which needs some intercept to work. Normally you do a DCT to an IAF. Or fly to a track in HDG mode.
