ils question

[knarf77]

hi there

I have an ils question what does the following mean

ILS RWY 06 DOWNGRADED TO CLASSIFICATION III (III/D/4 06 JUL 13:20 UNTIL 07 SEP 13:00 ESTIMATED

III/d/4 ? what does this mean ? are there other combinations?

if so were can i find them

rdgs frank

[SoftTop]

knarf77,

Is this a current NOTAM?

I'm a bit confused as to why it would be downgraded to Classification 3 - normally ILS is refered to by Category. If it is downgraded to CAT3 - that confuses me even more, because CAT3 is the top category.

If it's a current NOTAM, to which airport does it refer? If I have a look at the raw data that might help.

ST

[Doug E Style]

Seen this recently on NOTAMs for Amsterdam Schiphol.

[SoftTop]

Had a look at the Schiphol notams today and I see what you mean. I can't shed any light on the stuff in brackets, but it may relate to the CAT3 A/B/C definitions.

From memory the Annex 10 definitions are something like:

3A is horizontal visibility down to 200m
3B is vis down to 50m
3C is 0 to 50m vis.

It's probably something to do with that. There's also something in the back of my mind about EHAM being the only CAT3C airport in Europe. I think the UK ones that are CAT3 are all 3B. I stand to be corrected :ouch:

The consistancy of the NOTAM texts is also a bit all over the place. The ones I looked for were just spanning the next few days.

ST

[Hoover Pilot]

According to my manuals

The ICAO ILS clasification system consists of 3 characters (eg III/E/4)

1) Facitility performance category: I, II or III
2) limit point of course structure (ie point where localizer conforms to the required accuracy):
- point A: 4nm before threshold
- point B: 1050m (3500ft) before the threshold (cat I decision point)
- point C: glide path altitude of 100ft HAT (cat II deicsion point)
- point T: threshold
- point D: 900m (3000ft) beyond the threshold (cat III requirement only)
- point E: 600m (2000ft) beyond the runway end (cat III requirement only)
3) level of integrity and continuity of service 1,2,3 or 4 where 1 is the lowest and 4 the highest level

eg III/D/1 - requires us to operate to Cat I

HP