The Air Traffic Control Officers in the tower have instrumented RVR readings which would have been passed to the pilot. They have no discretion on otherwise reporting visibility. "Ranger guy in the landy"?? I think you are some years behind the times if you mean the counting the edge lights!
As ever HD, your sage words of common sense..and experience IMHO highlight the key to how this may have transpired.
IF the crew requested the reported RVR's before the approach ban point (1000ft AAL etc) then they ARE/WERE entitled to continue the approach as long as the values were above their respective minima. From that stage untill DA, it is entirely at the discretion of the PIC to continue or discontinue the approach with respect to reported minima. Then at DA there are specific external visual references required to continue to land...or to execute a missed approach.
At any stage between DA and touchdown, loss of visual reference mandates a Go-around.
Reading between the lines here..and assuming the aircraft was servicable to commence the approach (big assumption I know).then perhaps these chaps were unfortunate enough to lose visual reference at a point where they were effectively commited to a landing....i.e. idle thrust..in the flare or touching down..etc etc.
If this is the case..then it is just about as scary scenario as it gets close to the ground.
If however they were pushing their minima, then lets the chips fall where they need to fall.
In any case, I wish the crew a speedy recovery
