Pub User, gatbusdriver, legalapproach are spot on, some of you aren't reading the question correctly. teamilk&sugar, you'll have an interview with no tea, milk or sugar.
There are 2 separate issues here.
1. If RVR goes below minima once inside OM (or equivalent position) you may continue approach.
2. If there is a downgrade in aircraft capability inside OM (or equivalent position) you must perform GA.
KISS
Just revisited this thread after a period of time.
Scallywag, I don't know what SOP's your company uses, but I'm afraid in my case, I am right with this!
If the aircraft has a downgrade in equipment to LAND 2, it is still perfectly capable to autoland from CAT II minima.
If I am inside the OM, I am able to reset my RAD ALT to CAT II minima and proceed to that point.
I quote directly from my OPS manual:
From the Outer Marker (or equivalent position to the runway):
If the ASA degrades from LAND 3 to LAND 2, revert to Cat 2 minima. DH setting on the ADI may be changed, if practicable, at any time above alert height.
If the ASA degrade to NO AUTOLAND, the autopilots must be disengaged above 200ftAAL and a manual go-around or ifweather conditions permit (CAT 1), a manual landing performed.
So, I would be interested to know, Scallywag, why you think I would be invited for an interview with no tea & biscuits after reading that...!!
Not all aircraft and companies have the same operating restrictions you know!
Rgds