MetService - Annual Report 2011 - Crown Ownership Monitoring Unit

We’re here to talk about...
Dodging
ash clouds
When Chile’s Puyehue volcano belched ash into our
airspace in June and July, MetService’s robust monitoring
enabled Air New Zealand to keep flying safely.
MetService had just 36 hours warning
that the ash was heading our way. The
southern Andean mountain erupted with
the power of 70 atomic bombs, expelling
one hundred million tonnes of ash, sand
and pumice stone into the atmosphere.
Wind blew the cloud eastwards where
it shut down most of South America’s
air traffic before drifting across the
southern oceans towards Australia and
New Zealand. MetService models that
predict the dispersal of volcanic ash
were configured for local eruptions; ash
from half a hemisphere away was new.
MetService immediately made contact
with the airlines, Civil Aviation Authority
(CAA) and Airways. Two forecasters
worked extra shifts to bolster our
12-strong aviation forecasting unit,
which doubles as one of the world’s
nine Volcanic Ash Advisory Centres
(VAAC). They kept in close contact
with their colleagues in Darwin VAAC
and marshalled data from weather
models, satellites and ceilometers
that shoot lasers skyward to detect
atmospheric particles.
Pilot observation was helpful too.
However, calls from the flight deck
became scarcer as international
flights were cancelled. What some
pilots initially thought was volcanic
ash turned out to be haze.
MetService collated and verified
every scrap of information about the
ash cloud according to clear protocols.
For more than a month, we issued
advisories and SIGMETs (the equivalent
of severe weather warnings) to CAA
and the airlines.
With the ash cloud verified at 30,000ft,
Air New Zealand flew under it and
re-routed some flights, absorbing the
extra fuel costs. No planes encountered
the ash cloud and there were no safety
incidents. When we predicted the ash
would drift down to 10,000ft over the
South Island, the airline grounded a
handful of domestic flights, its only
cancellations.
When the skies eventually cleared,
CAA thanked MetService for “excellent
and rapid support” in observing and
validating the ash and keeping the
aviation industry informed. “Forecasters
handled this event in a thoroughly
professional and timely manner,”
said Keith Mackersy, CAA’s Technical
Consultant, Meteorology. New Zealand’s
flying public were the winners.
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Meteorological Service of New Zealand Ltd Annual Report 2011