Safety Recommendation
The Australian Transport Safety Bureau recommends that
Airservices Australia in conjunction with the Civil Aviation Safety
Authority and the Bureau of Meteorology develop a standard scale of
thunderstorm intensity for use within the aviation industry.
Airservices Australia supports the BoM argument against the
recommendation, namely:
"In some countries a single scale of thunderstorm intensity is used
in severe weather warnings to the general public. There is no
agreement currently, however, that it is appropriate to use such a
scale in aviation forecasts and warnings. There is good reason for
the reluctance to introduce such a scale. Among of the most
significant hazards for aviation associated with thunderstorms are
microbursts.
There is, however, no correlation between microburst intensity and
the intensity of the thunderstorm with which it is associated. An
intense microburst may develop from a weak storm and there may only
be a weak down draft from an intense thunderstorm. Ascribing an
intensity scale to a thunderstorm would not only not convey any
useful information to the aviation community, but could even be
counterproductive in the sense that it could lead pilots to believe
that there is less danger in flying into a thunderstorm that has a
low intensity than one with a high intensity, when this is not the
case.
It should be noted also that existing aviation forecasts, the
Terminal Aerodrome Forecasts and Trend Type Forecasts, already
allow for a description of the expected severity of the individual
elements of a thunderstorm - the strength of wind gusts, the
intensity of rain, the presence of hail etc, and the associated
reductions in cloud ceiling and visibility."
