Originally Posted by
jackal
I'll start with the first question:
Oh, and how does cat IIIC ILS figure in to all of this? Are AS's aircraft equipped with cat IIIC receivers? Does AS fly into any cat IIIC-equipped airports (with current procedures)? Have you ever landed in literally 0 visability? Does RNP replace or complement cat IIIC ? (I'm not sure it completely replaces it, since the minimums at JNU with RNP are still a 337-foot ceiling and one mile of visibility, from one article I read--but I'm not sure how to interpret this, hence why I'm asking here!)
OK, so that's one heck of a question to start off with. Hope it stimulates this thread, though!
Thanks again,
AlaskaCoho, for your time!
Whew! OK lets talk ILS now. Again ILS and RNP have no connection to each other. See RNP 101. The ILS is back to the 1950s radio transmitter positioned in this case at the end of a runway to provide very precise nav info to receivers in the aircraft. ILS Cat IIIB is the lowest that Alaska is certified to do. The difference is with C its zero visibility and a blind landing. Aircraft need rollout guidance to perform this approach. Cat B takes us to 600 feet vis, the Captain clicks off the autopilot on landing and performs the rollout on the runway the old fashion way.
Don't quote me on this but I think the FAA TERPS for RNP is a min of 350 feet ceiling and enough vis to see the runway. Each approach may have different min's based on terrain. But the min the FAA will allow is 350 ceiling using the RNP. JNU RWY 26 runway touchdown altitude is around 26 feet so the RNP min of 376. I can’t remember the exact number and I don't have my Jepps at home.
ILS mins are based on visibility not ceiling. ILS Cat I is 1800 feet vis down the runway no ceiling req. Cat II is down to 1200. Cat III is below 1200 with B down to 600 feet and C zero zero.
I have flown about 10 or 12 actual 600 foot approaches, ahh with an airline...
All Alaska pilots (I know from some reliable information) practice Zero Zero in the simulator each year during training. So in a pinch we…ahh they could do it.
The only time I flew zero zero was in the Air Force and I didn't want to, I was crying the whole way down. Very few airlines do IIIC since it costs so much to keep the aircraft certified.