1

The airport must, of course, be continuously monitoring the status of ILS, Lighting, RVR etc. From this status information, it seems logical that the CAT of any Approach can be calculated - but exactly what logic is used for each CAT please?

Also, does the DVOR (and HP DME) in any way affect the CAT of an Approach?

Andy Needham
  • 21
  • 1
  • Welcome to aviation.SE! You seem to have a few different things in the title and body of your question, so you might consider simplifying it if you can. We strongly prefer to answer only one question at a time (see the [tour] for more information on how StackExchange works). This question might be helpful, even if it doesn't answer everything you're looking for. – Pondlife Feb 07 '22 at 17:04

1 Answers1

4

An airport is not Cat I/II/III. A specific approach is.

Every ILS array, every IFR-rated pilot and pretty much every IFR-equipped aircraft (even a GA pilot in a Cessna), can handle a Cat I approach.

Additional ground equipment is required for a Cat II/III approach, as well as additional crew training and aircraft equipment. For cost reasons, this is mostly limited to airlines and their hubs.

Assuming properly equipped and working ground equipment and aircraft, and a properly trained and current crew, when cleared for the “ILS”, airline crews will execute the Cat II/III version of the approach if weather or maintaining currency dictates.

If anything does not meet those standards, a crew can only execute the Cat I version of the approach. If the weather at the airport is worse than Cat I minima, then they have to cancel or divert—something airline management doesn’t want happening at a hub, which is why they’ll spend the money making sure that doesn’t happen there.

StephenS
  • 27,747
  • 3
  • 62
  • 109
  • 2
    I was under the impression that the ground controllers had to know when CAT II/III was in use so they could keep protected areas cleared. – TomMcW Feb 08 '22 at 19:50
  • @TomMcW They protect the critical area any time the weather is below 800-2. You only have to notify them if you need (for currency) to do a Cat II/III approach in weather better than that. – StephenS Feb 08 '22 at 20:40
  • 1
    Yes, that's exactly what @Tom is saying, and it's a very good point. Our February safety briefing mentioned this. Controllers are not expecting crews to perform a CATIII approach in better-than-800-and-2 conditions and the crew should advise if they are. 7110.65 3–7–5b, and see also 3–7–5a1(b), which would not be applied in good weather unless specifically requested. – randomhead Feb 08 '22 at 20:56