ROCK SEVENaustralianflying.com.au 61
January - February 2015 AUSTRALIAN FLYING75 minutes after automatic
reporting ceased. Secondary
Surveillance Radars (SSR) trigger
co-operating aircraft transponders
to return f light data, and are range
limited. Automatic Dependant
Surveillance-Broadcast (ADS-B)
broadcasts the aircraft position
and track from the aircraft
without using base stations.
With SSR and ADS-B, an aircraft
vanishes from ATC view when a
transponder is switched off. The on/
off switch is there in case of faulty
identifications or electrical fire.
Otherwise, it should remain on.
However, there is little scope for
ground-based infrastructure over
vast oceans, putting aircraft out of
primary and SSR reach. MH370 in
particular has exposed a weakness in
the system, forcing aviation to look
for solutions in Earth’s orbit.Satellite solutions
Satellite constellations will cover
oceans and remote areas. Author
Nathan K. Watanabe’s study of the
USA Blue Force Tracking-Aviation
system found it was “proving itself
over the extended distances in
the vastness of Afghanistan with
tracking mission progress and
could provide a last known point,
should the need arise, to assist with
lost or downed aircraft.”
If satellites can trace militaryaircraft, they can trace civilian
aircraft, and a several new solutions
are being released onto the market.
US company Aireon is developing
a free Aircraft Locating and
Emergency Response Tracking
(ALERT) service, targeted for 2017.
Aireon CEO Don Thoma: “With
one global view of ADS-B equipped
aircraft, Aireon ALERT will provide
accurate and real-time tracking data
immediately to authorized search and
rescue operations, without requiring
airlines to equip aircraft with new
avionics or ... deploy new systems.”
One cost-effective means could be
Return Link Service (RLS), a new
feature in upgrades to the COSPAS-
SARSAT constellation that detectsemergency locator beacons. RLS
would enable the Search And Rescue
Master Control Centre (SAR MCC)
to activate aircraft ELTs remotely
to report position, without crew
intervention or interference, but
requires an alert to SAR MCC
AF447 made no Mayday call; loss
was established when ATC could
not make contact. Even if called,
ATC must pass details to the SAR
MCC to trigger the ELT.
ICAO considered solutions
including regular transmission of
aircraft position, or emergency-
triggered transmission. ICAO
proposed a 6 nm position accuracy, a
message every minute. Message cost
forced a compromise suggestion ofUS NATIONAL EXECUTIVE COMMITTEE FOR SPACE-BASED POSITIONING, NAVIGATION ANDTIMINGMAIN: Satellite tracking systems such as the
RockSTAR are becoming more prevalent in
GA operations right across the world.
ABOVE: An artist’s impression of a GPS IIRM
positioning satellite in orbit.“there is little scope for ground-based
infrastructure over vast oceans”