Or is there any way one CAN fly GPS approaches (i.e. get them activated) with an intercept INSIDE the FAF? Maybe with something more sophisticated than an almost 20 year old GNS430?
IIRC you cannot get the navigator to switch from TERM to APCH inside the FAF. I do not exactly the exact criteria for the switch to take place, but I have a vague memory it is within 2 NM before the FAF and on the final approach track. The PPL/IR RNAV/PBN guide may have the answer.
…actually, on the GNSW and GTN, once you activate VTF, it goes into the final approach sensitivity straightaway, anyway.
I think you all need to take a deep breath, download the appropriate sim from Garmin and play for ten minutes. The logic is good, and works surprisingly robustly.
With VTF selected, it will activate whichever leg you are adjacent to. Just draw mental lines at right angles to the FAF and MAP, and it will be SUSP if you are on the runway side of the MAP, otherwise it will be in the sensitivity appropriate to the approach (ie LPV, LVNAV or LNAV) and the part of the approach adjacent to your position will be active and magenta. Your heading makes no difference, but you do need to be within ~25 or 30nm (I did work it out once, but I have forgotten) of the FAT.
For an RNAV approach on my KLN90B don’t believe it will happen…CDI scale factor will stay in 1Nm Approach mode will not become active on the GPS navigator.
With the ILS you can do whatever flying manually, however it won’t couple to Auto pilot approach mode without a descent LOC. E.g. if you forget to set the course selector decently :-) or LOC deflection is to far off on my SN3500….
6.When the aircraft is 2 NM from the FAF, the KLN 90B
will verify that the proper integrity is available. If integrity
monitoring is available for the approach, then the
KLN 90B will change to the Approach Active mode. This
will be annunciated on the external approach status
annunciator as well as on the KLN 90B. The CDI scale
factor will also start to change from ±1.0 NM to ± 0.3 NM
additionally you could use OBS leg mode but forget the approach mode then…
4. Once established on the inbound course, you will
need to change back to the Leg mode to allow for proper
approach operation and automatic leg sequencing. For
best performance, the change back to Leg mode should
be made before the aircraft is 2 NM from the FA
NOTE:
It is mandatory that the unit be in LEG mode with the FAF as the active waypoint before crossing the FAFto activate the approach active mode and change to ±0.3 NM scale factor. The CDI scale factor changes from ±1.0 NM to ±0.3 NM over the two miles to the FAF. Delaying the switch from OBS to Leg mode compresses the scale factor change. This will make the transition more abrupt. If the switch from OBS to Leg is delayed too long it will not be possible for the KLN 90B to change to the approach active mo
This makes me wonder why I never had this issue, with my KLN94. Perhaps because I always fly GPS approaches from an IAF, not vectored onto the final approach track.
The 0.3nm FSD switch must be predicated on being in TERM mode (which auto-starts at 30nm radius of the airport, with a GPS approach loaded into the flight plan) and then passing within a certain distance of the FAF. Obviously you will never fly exactly via the FAF so it must be based on being within some distance of it.
But King GPSs don’t have the “activate the approach” feature; I believe that’s a Garmin (+Avidyne?) thing. What the GNS430 does I haven’t got a clue. @NCYankee might know.
I was vectored in France two months ago in Caen to the FAF very late like a rodeo ride after some switching back from If’s to radar vectors on a GPS approach LNAV. very weird. The unit was unable to go into approach mode 0.3 so I had to hand fly with 1Nm….If you fly to one of the IF’s and ATC does into interfere it works smoothly :-). Vectors to the FAF on GPS APP to avoided :-)
You can select the 0.3nm mode manually.
The main issue with doing that is that if you are some way off the intercept, it goes a bit unstable. It works only if the GPS is allowed to gradually reduce from 1nm to 0.3nm, which normally happens after the FAF.
True but when so close..the last thing you do is fiddling to change the CDI sensitivity….If it was IMC I would have gone missed for sure…… Changing the CDI sensitivity from 5 to 1 and 0.3 changes the behavior of the intercept angle when AP engaged…but now we are seriously off topic :-)
Which leads to the activate approach feature on the Garmin units using “vectors to final” activated which is far from ideal, when you need to change the IF points activate leg it takes a lot off turning knobs see this video..
I like the KLN as you have split screens for, all Legs are visible….its easy on the KLN’s ..teh concept does not exist
While the video makes sense, a couple of points.
It’s clearly an SBAS box (because at one point you see L/VNAV), whereas bos is clear that his issues are with a TSO-C129 box.
In my opinion, DCT DCT ENT is a much quicker way to activate a leg than using the menus.
