What does ILS category I, category II, category III means?

Question

What does ILS category I, category II, category III means?

Answer 1

http://en.wikipedia.org/wiki/Instrument_...

Answer 2

how low can you go?

Answer 3

Cat I means that the approach can be flown in bad weather, Cat II means that it can be flown in worse weather (lower minimums), and Cat III means that it can be flown in really crappy weather.  Special aircraft and aircrew certification is required to use these.

Answer 4

The CAT of ILS depends on 2 things: RVR and Decision height.

RVR is the Runaway visual range, and it's how far you can see on horizontal plane (assuming that you are on the runaway it says how many feet you can see). The DH is the altitude when the pilot must see the runaway lights, else he must abort the landing. The categories are:

CAT I: DH>200 ft, RVR>2400 ft

CAT II: 100 ft< DH <200 ft, RVR>1200 ft

CAT III: in general DH<100 ft and RVR<700 ft, but there are different sub-classes ABC. CAT III C dosn't require and DH or RVR, an aircraft with CAT IIIc can landing with no visual, only using instruments.