CAT II/III and lighting failure...

[Quincy M.E.]

If the met conditions meant that CAT II/III approachs were being made and you had your RWY and APP lights on, would the failure of, say, 3 RWY edge lights or a few APP bulbs blown mean that ops would have to cease? Or could the information be passed as 'essential aerodrome information' to the pilot so that they could decide for themselves?
Cheers
Q

[radar707]

The info would be passed as essential aerodrome information and the pilots would decide if they can continue. Most probably would as all they need to be able to do to complete the approach is see 1 light at DH. The fact that a couple of lights might be out shouldn't hinder operations, I've known 1 circuit of lights to have failed and crews continue to land as they still have the pattern available.

[Quincy M.E.]

ah I see, thanks. So there is no regulation specifying a percentage of lights that must be illuminated for the system to be servicable? And the aerodrome authority wouldnt close the RWY?

[Spitoon]

Depends a bit where you are I think. In the UK I recall there are some rules about more than two consecutive lights being u/s mean that the runway cannot be made available for cat II/III. I think also that there's something about more than 50% lights u/s being unacceptable too - so if your AGL system is set up as two circuits powering alternate lights, when one circuit fails you still see the same visual pattern but if one fitting on the circuit that is working is u/s (which would give three consecutive fittings out) you are more than 50% out. Hope that makes sense.

[Quincy M.E.]

Yeah that makes sense. I think I am going to have to trawl through CAP 168! I know I mentioned CAT II/III but I guess that lighting requirements would be the same for CAT I?

[Spitoon]

If you're in the UK CAP168 is your bible but you'll find that there are significantly more stringent requirements for cat II/III ops than for cat I. Also, you might want to look in the Aerodrome Manual and MATS Part 2 for local procedures about withdrawing runways from service etc.

[Quincy M.E.]

Just checked: inner 450m APP needs 95% for CAT II/III and 85% for CAT I etc.

Thanks for your help.