A few questions regarding RVR for takeoff... Let's say company is able to do 6-6-6 takeoff for arguments sake.

Touchdown RVR is required and controlling. Yes?
If Mid or Rollout RVR is missing, TDZ can replace. Yes?
If TDZ is missing, you cannot replace it so it's a no-go flight. Yes?
If one is reporting less than 600'RVR then it's a no-go flight (example 6/5/6). Yes?

On Arrival:
DFW ILS 17L RVR, no TDZ RVR, now what?

Thank you in advance!

What do your OpsSpecs say? Normally for takeoff you need one transmissometer down to RVR 2400/1800, two down to 1200/1000 and three lower than that. There is some relief if one system is temporarily inop.

What's the weather at DFW? RVR doesn't matter if the vis is above a mile.

If the TDZ RVR is missing but mid and rollout are OK, you may be able to land/takeoff in the opposite direction.

My company allows one to be inop, but if all three are operational they must be at or above the published minimums.

Well the reason why I ask is because the AIM says TDZ is required and controlling. If the TDZ is not reporting, then can an OpSpec actually lower an FAR requirement?

Yes, it can. That's the point of exemptions...

Depending on what your company Op Specs says, the Touchdown RVR can be substituted by the Mid RVR report.

Duh... Yes I knew that. Okay so depending on opspecs you can or can't use. Most Regional airlines have that capability.

Thanks!