After a long trial period at London Heathrow, British Airways has gone fully operational with microwave landing system approaches there and hopes to eventually see the capability offered at Gatwick.

The carrier says approach patterns will not change, but MLS permits a 20% increase in the landing movement rate that can safely be achieved in poor visibility, considerably reducing delays and cancellations during fog or heavy rain.

BA's MLS operations manager Capt Tim Price says 29 of the carrier's fleet of Airbus A320s and A321s have been equipped with a Thales multi-mode receiver, and the remainder will have been equipped by winter. Meanwhile, he confirms that the crews have been directed to use MLS as standard for Heathrow approaches, rather than the instrument landing system, so they are thoroughly familiarised with the equipment by the time the bad weather returns.

The advantage MLS confers is that it is not vulnerable, as the ILS is, to interference to the signal paths caused by aircraft landing ahead or crossing the runway. While Category 3 approaches are being used in fog, any potential interference to the ILS signal's integrity is unacceptable, so spacing between approaches has to be increased. MLS makes the spacing increase unnecessary, says Price, upping the number of landings that can be achieved within a given time.

Price says the business case for installing MLS receivers only makes sense for BA's short-haul fleet because they are slot-regulated, whereas the long-haul fleet is not.

In the longer term, he says, BA would like to see MLS fitted at Gatwick for the same reasons, particularly as it operates take-offs and landings from its single runway. At such "mixed mode" airports there would also be benefits to aircraft landing behind an aeroplane taking off. Price points out that, with ILS in Cat 3 conditions, aircraft may not be cleared to land until the take-off aeroplane has passed the localiser aerial at the far end of the runway, whereas with MLS it could be cleared as soon as the aircraft ahead is airborne. There is, however, as yet no plan to install MLS at Gatwick, says Price.

Source: Flight International