Runway Categories

[zoink]

Hi All

Another question which i hope you can help me with... And the topic is Runway Categories. Can somebody explain the difference between them (I, II and III) and/or point me to some technical documentation...

Thanks all
z...

[Chilli Monster]

Everything you ever wanted to know about runways and airfield licensing you can download from here - CAP168 - Aerodrome Licensing (http://www.caa.co.uk/publications/publicationdetails.asp?id=232)

[cortilla]

I think you're asking about the little red holding points at the edge of a runway. Basically wht thes signs mean is that if cat I landing is in operation (or II or III) then you have to stop at that red board so that your a/c does not interfere with the ground equipment. If this is so then i believe you are asking about the ILS capability of the runway.

isn't it also to do with the capabilities (and accuracy) of the ils systems for that particular runway. BTW a cat one allows you to go down to 200ft aal (above aerodrome level)before making a decision whether or not to go around. a cat 2 down to 100ft aal and the cat 3's (the 3 varying types) allow you to go down to less than 100' for landings. There are various visibility restrictions as well, however i can't remember them off hand.

Airfields also have a particular category relating to them (ranging from cat 1 to cat 9 i believe), and this is to do with the level of emergency response they can give you (mainly to do with the fire crews based there). Cat 1 being a fire extinguisher in the club house and cat 9 being the all singing all dancing fire crew that you would expect from a major international airport. (again might be the other way round but it's been a while since i did my atpl law writtens).

Edit: several points added and others corrected

[spekesoftly]

Bit more to it than just lighting - the ILS installation itself has to be CATII or CATIII capable and approved, back-up power supplies, runway safeguarding, approved ATC procedures etc etc.


Edit:
Before we go any further, I think we need to clarify if the original question pertains to ILS categories (1-3), or RFFS categories (1-9).

[reynoldsno1]

ICAO Annex 14 covers aerodrome design and operations. Instrument runways are also coded according to their use, and take into account width, slope, strip length and width, RESAs, clearways, stopways and obstacle limitation surfaces, amongst other things. It's a strange science....

[zoink]

SpekeSoftly & all

Thanks for all your replies.. The original question applies to the red boards which cortilla spoke of.. Which from their post seems to be the ILS categories. Apologies for any ambiguity...

So from cortilla's post, the aircraft have to stop at the board which represents the current ILS category in operation. So the question is how do aircraft and pilots know the current approach category? Is it assumed that for a large international airport eg Heathrow or Gatwick that the ILS category is II or greater? Or is this information passed on by a controller (i'm thinking of a pilot visiting and airport for the first time).

So all CAT I, II, III runway can accept all aircraft (assuming a decent runway length).. Correct?


The question comes from a recent wait at the runway entrance and looking at these red boards, just short of the runway edge.. (Heathrow)

Thanks for the help.. Very much appreciated...

[Jerricho]

The Cat I holds are sufficient for everyday "ILS" approaches. When Low Visability Procedures (LVPs) are in force, the ground environment becomes "safeguarded", and there is a specified area around the runway known as the Localiser Sensitive Area (LSA). During LVPs, these CAT II/III holds are used to ensure the LSA is free from aircraft etc that could interrupt or cause fluctuations in the ILS system. Which to a jet doing an auto-land could be a very important thing.

[Groundbased]

Would the fact that LVP's are in operation form part of the ATIS then?

Cheers.

[cortilla]

if normal ops are running then there will be no mention of which hold is required. However when there are LVP's in use then it will mention that LVP's are in use on the ATIS. However the controller will always tell you (in my experience which to be fair isn't at any major international airport) no matter what procedures are in place where he wants you to stop. eg G-**** cleared to taxi via taxiway alpha to holding point alpha one. However, and i'm sure someone here will correct me if i'm wrong, if lvp's are in use and you have to cross a runway but are delayed (i.e. cleared to blah blah hold short runway 27) then i believe you should stop at the red board for the relevant category of ops in use.

[055166k]

Don't forget that taxiway lighting [spacing] is also taken into account. Although aircraft can land in zero vis I understand that a minimum of 75 metres [or similar figure] IRVR is used...the problem being that after landing, taxying may be a practical consideration. I don't know about modern aircraft but I seem to remember that the Trident had a ground roll monitor to assist in position-on runway awareness.

[Spitoon]

Approval of Cat II/III operations are a combination of ground stuff (ILS equipment, approach lighting, runway lighting, taxiway lighting and runway safeguarding - and a few other bits), ground procedures known generally as 'Low Visibility Procedures', aircraft equipment and crew training etc. So it's not an easy subject to cover by a few quick posts.

On the holding point thing, ATC will always specify the holding point to which an aircraft is cleared. During LVPs it's not uncommon for some runway access points to be closed off to prevent someone inadvertently going on a runway.