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TotalBeginner
12th Dec 2016, 16:58
Can a fail-passive 737-800 perform a OEI CAT IIIA approach?

RAT 5
12th Dec 2016, 17:26
Your question is a technical one, and somewhere deep in the recesses of my RAM I think I heard someone tell me yes, and had done so on a test flight or sim.
Is it legal? Ah, that's another question.
Would you attempt it when all the doors have closed and the world is growing darker and smelly? Your choice when you are there.

RVF750
12th Dec 2016, 18:06
You certainly wouldn't do one if there was another option...Also as OEI is a flap 15 approach on most older aircraft it's not certified at all for Autoland at this setting.

Later aircraft do have F30 OEI figures. If your company allows it.

Fail Op aircraft have F30 OEI figures. Autoland? I'd rather not...

If you have an engine out you really shouldn't be going somewhere with CAT3 weather...#

lederhosen
12th Dec 2016, 19:23
I think there are circumstances, for example unextinguished engine fire, where it might be the lesser evil. Our manual says our fail operational aircraft are capable of it, but that we do not have permission from the authority. It also points out that go-around capability is problematic with flaps 30 OEI.

GlobalNav
12th Dec 2016, 20:28
All autoland systems must be demonstrated to safely cope with OEI occuring during the approach, and a safe go-around is an acceptable outcome.

OEM's may also elect to prove that their autoland system can commence an approach with OEI and land with normal touchdown performance, but they are not required to. The AFM or FCOM should include this condition if it has been approved.

aterpster
12th Dec 2016, 21:56
RVF750:

If you have an engine out you really shouldn't be going somewhere with CAT3 weather...#

You may not on an ETOPS diversion.

galaxy flyer
12th Dec 2016, 23:15
Comes under the heading of "superior pilots use their superior judgement to avoid using their superior skills". Nod shouldn't let an OEI divert turn into a CAT III landing.

Denti
13th Dec 2016, 07:29
The fail operational 737 is certified for OEI autoland and does it beautifully, the fail passive 737 isn't. As far as i know the second autopilot would disconnect on the fail passiv one, but i might be wrong, don't have the manuals here and it's been a while since i last had a sim event on that type. If dual channel autoland works there still would be the issue of the rudder as the fail passive version doesn't have a rudder servo. In that case the pilot would have to take care of it within the autoland limits to prevent autopilot disconnection.

I believe a few tried single channel "autolands" in the simulator and it kinda works, might be an option if dual channel is not available.