It is only the British Airways Shorthaul Airbus fleet that are equipped with MLS. About 70% of the fleet are now fitted out with MMR (Multi-mode Receiver) that enables the aircraft to track the Microwave system. The remaining aircraft are due to be be converted in due course.
All 4 runway ends are equipped with MLS at LHR, the theory being that in Low Vis Procedures, you can get tighter spacing between aircraft (or have a reduced gap behind a departure off the Takeoff runway). This is due to the much lower levels of signal interference with the MLS than ILS.
It is SOP that if you are operating a MLS equipped aircraft you should fly an MLS approach as opposed to an ILS.
ATC procedures require you to request the type of approach with Heathrow Director (he is the one looking after he holds) if you are not going to be doing a standard ILS. Crews are encouraged to practise RNAV approaches and these need to be requested too.
Hope that helps
T'bug
