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Cat 3 revert to Cat 2

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Cat 3 revert to Cat 2

Old 2nd Apr 2021, 02:58
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Cat 3 revert to Cat 2

Could anyone explain or give an example of how you can revert from Cat 3 Approach to Cat 2 ?
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Old 2nd Apr 2021, 13:53
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A good question and normally answered in the sim by, "it's probably an airfield thing and ATC will advise that they're now only Cat 2 capable".

Some research revealed the following unlikely additional scenario applicable in Canada:

Reported RVR 1200/600/600. Aircraft starts a Cat 3 approach. Required RVR 600/600/600

Reported RVR then drops to 1200/600/500. Cat 3 no longer possible as all three RVRs are required to be 600 or greater.

Cat 2 approach possible, as required RVR is 1200/600/advisory.
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Old 2nd Apr 2021, 13:57
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As far as Iím aware, reversion to cat 2 would happen as a result of some sort of failure or reduction in redundancy of the ground based ILS equipment.

Flying it would be as simple as resetting the minima to those stated on the plate. Provided the appropriate visual references are seen at the DH, the autoland can continue.
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Old 2nd Apr 2021, 14:18
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How? Either you request it, or they tell you to do it. Then you do it. Maybe you could expand the question a bit?
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Old 2nd Apr 2021, 15:12
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Fokker 100 would show "LAND 3" on the PFD for cat 3B autoland capable. If during its internal monitoring it detected a fault it would either downgrade to "LAND 2" which was actually cat 3A autoland or to GS/LOC which was cat 2 manual land with an autopilot engaged or cat 1 with no autopilot.
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Old 2nd Apr 2021, 16:24
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Ref CS-AWO All Weather Operations https://www.easa.europa.eu/sites/def...r%20CS-AWO.pdf

See CS-321 Cat 3 approach for equipment required.

If there is an equipment failure, see CS-221.

If your aircraft can still meet the equipment required by CS-221 Cat 2 approach, and if the aircraft is above the minimum altitude for reversion, and if allowed by you operational approval then revert to Cat 2.

If not then GA / divert.
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Old 3rd Apr 2021, 02:36
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In practical terms, you can plan for Cat III and revert to Cat II if the weather gets better than Cat II mins and/or equipment precludes Cat III. You would also have to brief the differences in handling Alert Height and Decision Height. Because of this difference, a Cat II briefing would also apply to Cat I, but a Cat III briefing is not complete for Cat II.
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Old 3rd Apr 2021, 02:42
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Thumbs up

All great answers,

Thank you
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Old 3rd Apr 2021, 19:44
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It would depend on the aircraft you fly, and the rules of your operator.

For the B737 that I fly, our rules, which I believe are a U.K. CAA requirement, are that anything below cat1 minimas have to be an auto-land, so we brief cat 3 auto land and cat 1 reversion available meaning that if at the OM/1000 feet the RVR is at or above cat 1 minimas we can descend to cat 1 decision altitude and land manually if an equipment failure precludes an auto land.

Boeing, and some regulatory authorities, allow the 737 to fly manual cat 2 landings in which case it would be possible to brief cat 2 reversion in the same manner if cat 2 RVR was available at the approach ban point. I’ve never really understood the CAA saying no manual cat 2 approaches for the 737, as they allow them for other types. Boeing say that cat 2 single channel manual approaches are allowed, and even if you disconnect the auto-pilot below 400 feet rad alt when the aircraft has trimmed itself nose up on a dual channel approach a manual landing is no big deal.

Obviously operating with a HUD with manual cat2 or cat3 is different.

Don’t know if that helps.
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Old 3rd Apr 2021, 20:20
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And don't forget the fail operational 737, which has even more capability like no DH operation (which we bugged for everything below CAT I) or fail passive OEI landing (50ft DH in that case). It gets complicated fast, one has to be aware of the options and restrictions for the type one is currently flying and the operation one is currently working in.
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Old 4th Apr 2021, 09:10
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Ah Reversion. Why would you 'revert' to CAT2 from CAT3? An airfield might change to CAT2 if it allowed increased traffic I guess, but they're unlikely to change their contract with you once they've told you and you've accepted a CAT3 approach.

In a 757 we have 3 autopilots, and at some point around 1500' they all come online, self test and you're expecting to see LAND3, Flare and Rollout armed.
Alternatives are LAND2 or MANLAND which means there's a 'problem' with one or two (although they might still be working)

In the event that you get LAND2 - the plane can still autoland it's just that we don't quite trust it as much - so there is an airplane specific limitation of 50'/200m - this is what we call reversion minima. Although it might sound like it, it's not CAT2 or 3A - you're still flying the same approach, you just have to rebug 50' on the radalt.

In the event that you get MANLAND - then obviously you're doing the landing.
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Old 4th Apr 2021, 14:02
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For the B737 that I fly, our rules, which I believe are a U.K. CAA requirement, are that anything below cat1 minimas have to be an auto-land,
I think that the CAA requirement is for the simulator currency to include a certain number of hand flown approaches, if you're going to put hand flown cat 2 into your manual.

Most airlines don't want to bother with that, so just write "autoland only" into their manuals, and thus you can fly cat 2 with the same training as cat 3.
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Old 4th Apr 2021, 16:33
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Checkboard confirmed.
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