Multi Surveillance
Discussions
among air-traffic
managers and
ground system
suppliers
suggested that
multilateration
will be more
than a bridge
to ADS-B.
Air traffic surveillance beyond radar will surely rely on the GPS-based position reports of Automatic Dependent Sur- veillance-Broadcast (ADS-B), but likely
also on the transponder replies of multilateration
(MLat) and its application as wide area multilateration (WAM). That was one of the takeaways
from this year’s ATC Global conference, held
March 9-11 in chilly Amsterdam.
While ADS-B is steadily progressing in the
United States, Canada and Australia especially,
WAM systems are popping up like a spring tulip
bloom. Announcements by leading multilateration system providers at ATC Global covered
opposite corners of the North Sea. Era a.s, in
partnership with Holland Institute of Traffic
Technology B.V., has installed a WAM system
for Dutch air navigation service provider Lucht-verkeersleiding Nederland affording low-level
and overflight surveillance of the Dutch portion
of the sea. In January, the system passed functional performance testing.
NATS Services of the United Kingdom is
using a Sensis Corp. WAM system for helicopter
flight-following initially, and separation service
eventually, off the coast of Scotland, providing
visibility of thousands of ferry flights between
Aberdeen and North Sea oil and gas platforms.
Multilateration surveillance is being applied
for special use airspace by the U.S. military
services and for precision runway monitoring,
terminal area or enroute surveillance in locations
including Europe, Russia, China, the United
States, Canada, Australia, Saudi Arabia and
South Africa.
Three years ago this month, we published an
article on multilateration with what at the time
seemed like a provocative headline: “
Multilateration: Radar’s Replacement?” Given the rapid
rate of adoption of multilateration systems that
was evident in April 2007 and continues apace,
that headline is not so edgy anymore. Discussions among air-traffic managers and ground
system suppliers at ATC Global suggested that
multilateration will be more than a bridge to
ADS-B but a complement and backup to that
technology as well.
Ludmilla Gonzales, Thales ATM business
development manager, gave an excellent primer
on MLat, WAM and ADS-B, covering some
of the pros and cons of each. Chief among the
pros of multilateration, of course, is that all it
requires of the airplane is a working Mode A/C,
Mode S or military IFF transponder to reply to
secondary surveillance radar or ground station
interrogations, hence no new onboard equipment required. The system also monitors ADS-B
broadcasts over 1090 MHz Extended Squitter or
Universal Access Transceiver.
Thales ATM has a product strategy that cov-
ers each of the surveillance options, Gonzales
said. “We have developed an ADS-B, multilat
and WAM product family that is able to answer
any operational needs — enough for ADS-B
only, for multilat only, for WAM only,” she said.
“But as the trend is to mix those technologies,
we have three technologies that can be combined
on one platform.” Air traffic managers “need to
perform a kind of balance and to maybe address
the mix of technology in order to optimize the
surveillance solution in your dedicated area.”
Later that same day, I worked my way into a
crowded workshop sponsored by Sensis with the
apt title, “Multimode Surveillance — the Cor-
nerstone of NextGen Surveillance.”
Multimode surveillance combining multi-
lateration and ADS-B “provides cooperative
surveillance in a mixed equipage environment —
that is, ADS-B equipage universally is something
that is going to take place over multiple years,”
said Mike Gerry, Sensis vice president of air traf-
fic systems, products and programs.
“A multi-mode surveillance system provides
surveillance throughout that transition period,”
he added. “And if you believe that the transition
is the end state, it’s a system that can be deployed
now while providing services now and for the
future.”
Andrew Desmond-Kennedy, Eurocontrol
senior expert for surveillance, offered validation
of the idea of multi-mode surveillance as an end
state. According to his presentation, Eurocontrol
“fully supports WAM as an acceptable means of
surveillance.” Through its CASCADE data link
services program, the agency will support “an
integrated approach to WAM and ADS-B.”
WAM, he concluded, is “one of the
cornerstones of European surveillance.”
