Hi Guys,I have the FMC option setting for "Glide-Slope Capture Before Localizer" set to NO. Yesterday, I was flying into KRNO via the KENNO1 Approach. The turn to final is pretty tight, and puts you right at the FAF, with the GS already decending prior to capturing the LOC.My question, how many people turn on the "Glide-Slope Capture Before Localizer" feature for this reason, or is it better practice to configure the plane ahead of time to be ready for the "early" GS capture before the LOC captures?Thanks,John

Edited March 5, 201214 yr by johndrago

Well many planes in RW can't descend before that, at least as far as I know. It is totally blocked so what I do is enter VS to about -700 or something (depending on speed). The reason I think that this feature exists is to make sure that you are aligned to the runway before you descend. Let's say that you are way out from the LOC path and you start descending according to G/S (which can happen) the aircraft would fly into the ground. I think that they have this to prevent that, but it's just a guess.But back to your question, entering a V/S would ensure that you have manually overridden the G/S and are aware of what is going on.Just to confirm, I am not a real pilotManfred

Edited March 6, 201214 yr by sandpatch

That is about the correct reasoning. Glide slope terrain clearance is only guaranteed on LOC (and in some immediate vicinity). Of course in most places like Amsterdam, London or JFK, there is hardly anything to hit, but there are places that descending on GS out of LOC could lead to serious accidents (like LOWI, even if it is properly an offset localizer with glideslope information, not a real ILS)

Very true. IMO it's not exactly great practice to descend on a G/S if your LOC hasn't been established yet. I was always instructed to be at a maximum of half-scale deflection on the LOC before I was allowed to slide down the slope. I would reckon that's why many APs won't let you do that in the first place.

Edited March 6, 201214 yr by badderjet

"KENNO1 Approach"? you do not want the G/S here.KENNO1 is the STAR."Glide-Slope Capture Before Localizer" ... Yes.If doing LNAV approaches you may not be on the LOC but you will pick up the G/S and you want to capture it and start down.

Edited March 6, 201214 yr by vonmar

At American our planes are configured to allow GS capture before LOC. The rule is don't arm approach until the LOC is captured. An excepton is when doing a visual approach it is easier sometimes if you can capture the GS before you are on the LOC.

At American our planes are configured to allow GS capture before LOC. The rule is don't arm approach until the LOC is captured. An excepton is when doing a visual approach it is easier sometimes if you can capture the GS before you are on the LOC.

On some RNAV approaches (also) you will not capture the LOC because its path is not on the LOC ... thus, "allow GS capture before LOC" should be on.And for a visual you do not have to use the FMC.