air navigation authority STNA is considering providing both Paris airports with
microwave landing systems (MLS) after ordering installation of the equipment at
Toulouse in order for Airbus to conduct MLS certification work.
MLS was once hailed as a future successor to instrument landing systems (ILS)
the technology is seen as inferior to satellite-based navigation, with the
result that the civil aviation industry abandoned MLS in favour of
the French move signals a possible revival of MLS as a tool for increasing
capacity at Paris Charles de Gaulle and Paris Orly during Category III weather
conditions. Precision landing equipment based on global navigation satellite
systems (GNSS) are currently unable to provide the navigation accuracy required
for Category III approaches.
has ordered a single MLS system for Toulouse and has placed options on seven
more: four for Charles de Gaulle, two for Orly and a single system for training
purposes. It has contracted French air traffic control systems manufacturer
Thales ATM – formerly Airsys ATM – to provide the MLS equipment.
main reason [for looking at MLS] is that lots of people realise that GNSS is
not available for Category III and will not be for the next few years,” says a
spokesman for STNA’s communications and navigation division. “We’ve not changed
our mind [by resurrecting MLS] but are trying to solve a medium-term problem.”
signals are sensitive to movement from aircraft and other vehicles and each ILS
installation has a critical zone around it which must remain free from
interference. But for MLS equipment this zone is much smaller. MLS installation
would theoretically allow Paris air traffic controllers to keep aircraft more
closely spaced during approach and landing without risking the MLS signal
ILS the sensitive and critical area which has to be protected is large,” says
the spokesman. “With ILS we have to make sure this whole zone is clear.
Arriving aircraft have a direct impact, and this is one of the reasons we have
to keep them separated. But with MLS the biggest limitation for [closer]
the MLS installation in Toulouse will primarily enable Airbus to conduct
airborne certification tests for British Airways aircraft – as part of the
carrier’s individual drive to implement MLS for its London Heathrow operations
– Air France is expecting to reach a decision on its own MLS strategy by the
end of this year.
we decide to install MLS on the fleet it will only be to increase the landing
capacity at Charles de Gaulle,” says an Air France spokesman. “Retrofit of this
equipment is very costly. We need to have good information and know that the
traffic increase in low-visibility conditions would be good enough to justify
it – we can install MLS only if there is a significant increase in the number
of low-visibility movements.
France would install MLS avionics on its entire short- and medium-range Airbus
fleet. The carrier presently operates more than 100 aircraft from the Airbus A320
family, and the spokesman says that a full retrofit would probably take until
around 2007 to complete.
says that Air France would need an increase of around five or six movements per
hour in low-visibility conditions at Charles de Gaulle in order to make the
retrofit worthwhile, adding: “We’ve not yet received confirmation that the
number of landings will be enough for the required return on investment. But we
hope to obtain this data at the end of the year.”
civil aviation authority DGAC, STNA, Air France and Paris airports operator
Aeroports de Paris will continue discussions on whether to proceed with a full
MLS implementation at Charles de Gaulle and Orly. The STNA spokesman says: “It
is very difficult to say when a decision will be made. The decision really has
to be taken quite rapidly but there is no real target date.”