Aluminium Shuffler,
I'm pretty sure that is incorrect. What is the point in roll out guidance for Cat IIIB if there are only two autopilots, limiting it to Cat IIIA?
Well, you're wrong there.Cat IIIB capability does not require 3 autopilots.Denti was correct in his statement,the later versions of the 737 NG are capable of CAT IIIb operations.
As far I recall among other things required there have to be 3 seperate inertial guidance sources to provide data to the FCCs.On the later variants of the 737 NG the third source is the ISFD standby instrument unit.Plus Boeinog implemented changes to the rudder system to allow the Autopilot to control the rudder during rollout guidance.
The a320 btw is also Cat3b capable as far as I know and also features only 2 AP.
Kind regards,
Vee1.rotate
Edit:oops,Denti beat me to it.