of the civil aviation community have secured the preservation of spectrum for
microwave landing systems (MLS), one of the priority issues put forward by the
industry at this year’s World Radiocommunications Conference (WRC) in Geneva.
follows a gradual revival of MLS as an option to provide precision approach
capability at main airports owing to the lack of availability of suitable
satellite-based landing systems – which had originally been expected to
supersede MLS. Several airports have pressed ahead with installation of MLS to
maintain operations in low visibility.
radionavigation services have been allocated frequencies in the 5-5.250GHz
range with the 5.030-5.150GHz sub-band for MLS currently the only defined
aeronautical function within this range.
channels presently occupy only part of this sub-band – from 5.030GHz to
5.091GHz – but ICAO expects to need channels above 5.091GHz for future MLS
satellite navigation systems could provide a future solution, MLS can be
implemented now and is already operating at certain highly-congested airports,”
says a spokeswoman for the Air Transport Action Group (ATAG). “It is
anticipated that the number of air and ground MLS installations will increase
and that they will need to operate in this extension band.”
WRC’s Committee 5 panel has granted a request to preserve the current
allocation of spectrum for MLS by overhauling an old resolution passed in 1995.
updated resolution also requires studies on compatibility between new
aeronautical radionavigation services and commercial fixed-satellite services
in the 5.091-5.150GHz frequency band – although there are indications that,
given enough geographical separation, MLS receivers and fixed-satellite
stations can co-exist.
a nutshell the current regulatory mechanism for MLS will be maintained,” says
the International Telecommunication Union (ITU), which hosts the conference.
the fixed-satellite service was due to become secondary in status to
aeronautical services from 2010 the updated resolution extends this deadline to