70 AUSTRALIAN AVIATION
(IAVW) to provide warnings to the
aviation community, comprising of
nine Volcanic Ash Advisory Centres
around the world. These units advise
the international aviation industry of
the location and movement of clouds
of volcanic ash.
In Australia, the Volcanic Ash
Advisory Centre in Darwin covers
Indonesia, Papua New Guinea and
a section of the Philippines. The
volcanoes are colour-coded by an
internationally recognised four
level system ranging from a ‘Green’
normal, non-eruptive state, through
to ‘Red’ which forecasts an imminent
eruption with ash reaching the upper
atmosphere.
All arms of the aviation community
play significant roles in gathering
and disseminating information,
including air traffic management and
the Bureau of Meteorology, which
provides Volcanic Ash SIGMETS as
part of their aviation weather and
warning services. Additionally, many
airlines possess their own system
of notification of volcanic activity
to flightcrews which can be relayed
through the company ACARS system.
Also within the airlines are
dedicated teams that assess, mitigate
and monitor the risk associated with
volcanic events. Just as the volcanoes
have levels of threat, the teams have
a range of plans of action based upon
the circumstances at the time. It may
call for rerouting flights well clear and
upwind of any potential danger, or
cancelling services altogether.
These teams constantly monitor the
situation and could be seen in action
during the recent events in Bali. On a
daily basis flights were cancelled when
the risk was assessed as too great,
while an unexpected change in wind
direction did see a potential window
for operations during that period. For
this to occur, the airline teams need
to be both strategic and dynamic in
order to react when the opportunity
avails itself. This may also involve
positioning crews at the ready in
relatively nearby ports.
At all levels and across the globe,
government bodies and airlines alike
constantly monitor the potential for
volcanic activity with the information
available. The view is to mitigate
against an ash encounter ever
occurring as even a minor encounter
can cause substantial damage to an
aircraft. Even so, there are procedures
and training in place for pilots should
they be faced with volcanic ash despite
all the measures designed to avoid it.The pilots’ role
Each make and model of airliner will
have its own defined set of procedures
to deal with flight into volcanic ash,
just as each airline will have its own
training syllabus, so it is impossible to
cover every case here. As such, each
relevant set of operating manuals
and procedures should be consulted.
The overwhelming message is one of
avoidance, but the nature of aviation is
to prepare flightcrews for all manner
of emergency scenarios and a volcanic
ash encounter is one such potential
emergency.
Should the encounter occur,
first and foremost the crew needs
to continue to fly the aircraft safely
and avoid the numerous distractions
that will undoubtedly occur, from
crackling radios and flickering lights
to St Elmo’s Fire. As the pitot probes
may be feeding erroneous data, it
is important to fly an appropriate
pitch attitude, and power setting if
able. The indicated airspeed shoud
be treated with a degree of suspicion
and there may be a need to initiate the
non-normal procedure for flight with
unreliable airspeed at some point.
Just as visual flight rules pilots are
trained for an encounter with cloud,
initiating a 180-degree turn mayFlights into and out of Bali were
disrupted in late November
thanks to Mount Agung. Pictured
is a file image of a Jetstar 787 at
Denpasar.ROB FINLAYSON‘Airline
teams need
to be both
strategic and
dynamic.’