The last 747-200s I flew, had the full Cat.IIIb equipment.
But NO 747s were ever certificated for it. They were Cat.IIIa airplanes.
As far as certification was concerned...
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Sometimes in the late 1990s, our airline stopped doing any Cat.IIIa.
They found Cat.II minimums to be quite sufficient for our operations.
Something along the lines "is it necessary" to have full Cat.IIIa capability...?
To fly (statistics) 3 or 4 approaches per year into MXP...? - It was NOT...
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We kept operating merely with Cat.II until their recent final retirement.
Yes, we (at times) operated the full Cat.IIIb to see if it still "worked".
That is including the ARC (Automatic Rollout Control) = which is Cat.IIIb.
Such capability was maintained, until the last days.
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Quoting a (now retired) chief pilot "if you ever need all that - use it..."
After all, we knew it worked last week on that plane.
Guess what...? I have no problems with such philosophy.
But then I am retired too. Cat.IIIc rocking chair if you care to know.
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Happy contrails