As one who was involved for Balpa in the technical discussions on Cat III RVR, I can confirm that the 75 metres was at the request of LHR fire service. They could not guarantee finding an aircraft in less.
Notice that - thanks to green taxi lead-ins and an excellent ground movement radar - taxi-ing (at LHR at least) was considered less of a problem. We also had lo-viz taxi charts with headings so that the FO could monitor progress.
Last edited by scotbill; 17th December 2011 at 14:44.
Reason: typo