Firstly, I really do not want to dredge up the on-going debate that is the 'new' ILS phraseology - that really has been done to death and there are several threads about this on here.
The question....
At my airfield we have instruction that impresses upon us to use the conditional instruction to descend on the glidepath when establised on the loc. Fine. Depending on the runway in use we often get a stream of straight-in approaches and descent is given to 2.5A is more or less given on first contact. Now, if I say to a pilot (who might be at, say, 30nm descending from FL90):
"Descend to altitude 2.5A"
And then I subsequently say (at an opportune moment):
"Turn right XXX, closing the localiser etc etc, when establised descend on the glidepath"
Am I right in thinking that the pilot will descend to 2.5A and then further descent will be with the glidepath? (
even if they become localiser established at a level above 2.5A and probably outside the glidepath DOC - 10nm).
MATS pt 1 states:
"Controllers shall not instruct pilots to descend on the ILS/MLS when the glidepath intersect would be outside the glidepath DOC."
Which suggests that this method is OK as I have given positive instruction to descend to an altitude that means the aircraft will intercept the glidepath within its DOC.
If this is not the case and in actual fact the pilot arms the approach AP to descend with the glide
as soon as the loc is captured, and this is 'normal' practice, then when does the CAA ever anticipate that the excerpt above would be applicable?
It hasn't caused me or others any problems yet but I've heard stories of 'false glidepaths'.
Sorry if that's long-winded, would be interested to get a pilot's view as well (regardless of what the procedures say or what controllers assume).
Thanks
