What is needed to take off in CAT IIIb weather and how is it done?
Under the US FARs (at least part 91) nothing special is required to take off in CAT IIIb weather besides an operational (and IFR-legal) aircraft and pilot. As mentioned elsewhere you can legally make that Zero/Zero takeoff where you can't even see the runway under your nose.

It should go without saying that doing so would be incredibly stupid (we (and the FAA) have said so anyway), but from a technical standpoint there's nothing preventing the operation except the knowledge that you might run off the side of the runway into a ditch and bang up your aircraft and passengers.



In terms of what would be required to make the takeoff safely, without running off the side of the runway into a ditch, I'd posit that you would need the same capabilities as you'd need to make the CAT IIIb landing safely: Aircraft systems that let you reliably track down the centerline for takeoff (using the ILS or something of equivalent accuracy for guidance, and runway centerline lights).

You would also need a reliable way to get from the gate to the runway, so taxiway centerline lights &amp; stop bar lights are a must, and probably ASDE-X or its functional equivalent with a controller monitoring it to help ensure you don't taxi into another aircraft.

All of the above is predicated on, among other things, being able to see the lights I mentioned. The "takeoff guidance system" mentioned elsewhere adds synthetic vision into the mix which further enhances safety (and in the airline world allows takeoffs down to 300ft RVR). From what I can glean from the Rockwell-Collins marketing material their HGS seems to be able to provide "follow the green dots" taxi guidance (and presumably runway centerline guidance for the takeoff roll as well), providing redundancy for the lights I described above to help the pilot ensure the aircraft is going where they want it to.