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AlaskanFlyboy

ILS Approaches and Dual AP

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Can all ILS (Cat I/II/III) approaches be flown with dual AP and autothrust or are there restrictions? Or is it generally advisable to fly only Single AP, except for CAT III?Also, when is the decision made which ILS approach to choose?Thanks.

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Catagory I does not require APCatagory II requires 2 AP units functional at the final approch fixCatagory III requires 3 AP units functional at the final approch fix and 2 prior to touchdown.as I understand it, no catagory of approach and landing require autothrottles.The decision is based upon which catagory the crew, aircraft and the runway are certified for.There are very few CATIII airports in the US (I believe less than 9)Both cloud ceilings and runway visiblity dictate which type of approach is used (assuming the 3 items above are meet). Often, if the conditions vary between I and II, or II and III, the crew will breif for CATIII. That way, if conditions lift (i.e. get better) after the final approach fix, all requirements have been meet. All of this is just my current understanding and opinion. I am sure a internet search will yeild much more.

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In addition I believe CAT III also requires crew certification, not just aircraft and runway certification?

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yes sir, thus the statement"The decision is based upon which catagory the crew, aircraft and the runway are certified for."

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CAT II also requires aircraft and aircrew certification.----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

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CAT III isn't that rare, Spokane International (KGEG) has CATIII into runway 21. It is usually only at airports that habitually have bad fog, since the system has such a high cost.I know also that I've seen a CAT II plate that has the comment "Cat II minimums not authorized when control tower closed.". I'd assume this is probably on all plates for airports with towers closing at night, but my knowledge of CAT II/CAT III operations is limited as I don't deal with them in the real-world and were only covered in passing over the class I had on 135 ops.----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

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agreed, and again the statement..."The decision is based upon which catagory the crew, aircraft and the runway are certified for."

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CAT III is itself suddivided into IIIa and IIIb.IIIa is rather common, IIIb is still pretty rare.Maybe the number of 9 airports is for IIIb airports only.

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>>Both cloud ceilings and runway visiblity dictate which type of>approach is used (assuming the 3 items above are meet). >Often, if the conditions vary between I and II, or II and III,>the crew will breif for CATIII. That way, if conditions lift>(i.e. get better) after the final approach fix, all>requirements have been meet. >Just to clarify, except for some approaches, a handful in the US, cloud ceilings are not a controlling factor in whether an approach is legal to conduct. In most cases, visibility is the only controlling factor.Also, if conditions are marginal CAT I, I would brief and conduct the approach as a CAT II, if available. That way, if conditions are worse than reported at the end of the slide, I can still land.

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Kevin,My understanding is that in the US, visibility is always controlling for all instrument approaches.14 CFR 91.175 Takeoff and landing under IFR (emphasis mine)...(d) Landing. No pilot operating an aircraft, except a military aircraft of the United States, may land that aircraft when

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http://204.108.4.16/d-tpp/0510/05889ROARINGFORK_VIS15.PDF - 6,000 ft ceiling required - true an unusual airportI believe if you check every approach has a ceiliing requirement in addition to a visibility minimum. It might be called Decision Height - DH, Minimum Descent Altitude - MDA, or Height Above Airport - HAA - but the practical effect is if the ceiling is below this altitude - you are not supposed to attempt to land.

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My recollection was that there were one or two airports out in the mountains of CA or CO that had a Ceiling Required restriction in the minimums. Of course, I can't find any of those now. So maybe I am completely off. Outside the US, having a Ceiling Required note on the plate is a little more common. A flip into one of my Jepp binders quickly produced Flores, Guatemala (MGTK) which has a minimum ceiling in its approaches. But I could have sworn....The Roaring Fork Visual approach has a ceiling minimum because it is a Charted Visual Flight Procedure. It is not an instrument approach.Even for commercial operators, if the ceiling is reported below the DA or MDA, you are still legal to conduct the approach. In real life, even if you are inside the cloud, the approach lights may still be visible to you through the cloud, allowing you to continue your descent. Also, a ceiling is not necessarily a solid deck of clouds, since "Broken" also qualifies as a ceiling. There could be breaks in the clouds allowing you to plainly see the necessary components of the runway to continue descent and land. This is why visibility is the only controlling factor in instrument approaches.

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Hey Reggie,Your last statement is simply not true. The part of the regulations I mentioned eariler, 14 CFR 91.175, is hard to parse, but there are separate sections on when you can legally operate below the DH or MDA and a separate section that says when you can legally land once you have found the runway.Kevin, When I went through 135 indoc training, my employer covered the visibility versus ceiling issue. Here are a couple of references I found on the web. Check 'em out:http://www.superawos.com/ny-fpo.htmhttp://www.superawos.com/32_federal_register_13909.htmJohn

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I misreported. It's Runway 03 that has the CAT III and it's III B----------------------------------------------------------------John MorganReal World: KGEG, UND Aerospace Spokane Satillite, Private ASEL 141.2 hrs, 314 landings, 46 inst. apprs.Virtual: MSFS 2004"There is a feeling about an airport that no other piece of ground can have. No matter what the name of the country on whose land it lies, an airport is a place you can see and touch that leads to a reality that can only be thought and felt." - The Bridge Across Forever: A Love Story by Richard Bach

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