Just in case anyone thought I was saying that I
depend on the Radalt in a Cat 1 approach, perhaps you should re-read my previous post and point it out to me. It isn't there. I
DID say, however... "
I believe in using everything at my disposal to keep my operation safe."
To demonstrate what I mean by "everything at my disposal"...
Imagine a runway on top of a cliff. Half a mile out you could be at 500' agl. Two hundred yards later you could be 20' agl and all of a sudden your decision height is GONE because the pilot was relying on RadAlt rather than Baro for a Cat I approach and didn't read the notes on the bottom of the plate properly.
First off, again, I haven't advocated reliance on Radalt for a Cat 1 approach. I don't know about anyone else, but I would have taken note of the aerodrome elevation and threshold elevation in my pre-approach briefing. I reckon that this simple safety precaution would resolve this particular situation.
Landing on ILS Rwy 01 at Guatemala, the Radar Altimeter altitude jumps from 600 Feet to 100 Feet in one second as you approach the threshold. Radar Altitude is completely useless at D/H.
See my response to the immediately preceeding quote.
The ILS at Guam in 1996 with the G/S out has high ground on finals with a ****** factor of the VOR/DME being 3.3 dme SHORT of the runway threshold.
I've been there and this did not present a problem to me. Guam has a DME which I can use to cross-check the situation at 3.3 miles from the threshold. If I'm on the right profile, I'd expect to be something over 1000 FT AMSL when passing the VOR - for the moment I can't recall the crossing height there, but a Radalt warning at 3.3 miles from the threshold would not take precedence over the altimeter indication in my mind.
I think the point that needs to be made here is that a certain amount of pilot brain power is necessary. This is applied at the pre-approach briefing (or whatever you choose to call it), and during the approach. This, naturally, includes all the logic steps such as double-checking the altimeter setting, using the DME and setting the Radalt to confirm DH at DA. The time you stop thinking is the time when you're in greatest danger. Hence, as I said at the outset, I always use everything at my disposal to keep my operation safe.