LVO - when is A/C clear of CATII/III ILS sensitive Area?
 

Hi!

Which part of the A/C must be clear of the color-coded TWY centerline to vacate ILS-sensitive area?

So far, I've heard two schools oh thought on this:

1) The TAIL must be clear of the color-coded

2) it's sufficient to clear the COCKPIT only - the length of the largest a/c intended to operate into the particular airport is already taken into account when ILS critical area is established.

#2 makes more sense to me, as the flight crew cannot accurately determine the position of tail... Can anyone direct me to some regulations covering this?

I go with #1. I've been to airports where the difference between the CAT 1 & CAT 2/3 holding points is less than half the length of my a/c. B738. The amber/green lights reverted to green when vacating across the CAT 2/3 holding point. Thus my tail was still inside even the CAT 1 holding point. From this I assumed it was a requirement for the crew to assess when they were totally inside the protective area.

Go with #1.

What's the regulation for reporting clear of a runway? All parts of the airplane need to be past the hold-short line or 200'.

According to CAP168, in the UK the coded Twy centreline starts/ends at the perimeter of the ILS critical/sensitive area OR the lower edge of the side surface of the Obstacle Free Zone, whichever is farthest from the runway. So in practice this could mean when vacating a runway and the taxiway lights become all green, as seen from the cockpit, the tail could still be inside either of the above until the whole aircraft is beyond the colour coded section.

From the LGW notes from the LGW IAIP.

And now we have confirmation that while not quite being close to God pilots do have eyes in the back of their heads. Bring on retractable wing mirrors.

Simple math: divide the lenght of your aircraft by your taxi speed in m/s and start the time when passing the last amber light. This way you can submit your report at the exact moment in time if you happen to care.

Thanks for replies gentlemen. Looks like it's the tail that has to clear the color-coded line. I would still appreciate some official refernence (Icao annex or some such)...

The reason I am asking all this is not to "submit report at the exact moment in time if I happen to care" as Hahn suggested. It's because the other day, in an effort to clear the tail from the ILS sensitive area I taxied beyond clearance limit, which happened to be at the end of the color-coded line (and was inadequately lit, or at least I couldn't see it). I just want to avoid similar misunderstandings in the future...

I cannot see any question here. Surely common-sense dictates that the markings are there to give adequate separation on parts of aircraft that have supposedly 'vacated' and thus it must be the part of the 'vacated' aircraft nearest the runway?

Annex 14 will give you most of it. I think there's a Manual of LVOs too.

Thanks for replies gentlemen. Looks like it's the tail that has to clear the color-coded line. I would still appreciate some official refernence (Icao annex or some such)...

Being facetious, I admit, official reference is common sense. You are taxi-ing out to the LVO rwy. You stop at the beginning of the amber/green lights, at the CAT2/3 Hold, as these indicate your nose is going to enter the protected area. Turn your a/c around as you vacate across the same holding point. If your nose would violate the protected area, then so can the tail. QED. KISS.