Recommendation R20020176

Recommendation issued to: Bureau Of Meteorology

Recommendation details
Output No: R20020176
Date issued: 20 September 2002
Safety action status:
Background: Why this Recommendation was developed

Output text

Safety Recommendation

The Australian Transport Safety Bureau recommends that the Civil Aviation Safety Authority in conjunction with the Bureau of Meteorology and Airservices Australia develop a standard scale of thunderstorm intensity for use within the aviation industry.

Initial response
Date issued: 19 April 2004
Response from: Bureau Of Meteorology
Action status: Closed - Accepted
Response text:

The following response dated 13 April 2004 was received from the Bureau of Meteorology:

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.

The Bureau would not support the introduction of a standard scale of thunderstorm intensity for aviation purposes, but will investigate options for providing additional information to pilots and controllers that might serve to highlight the potential hazards of particular meteorological phenomena. The Bureau has significant skills in the area of severe thunderstorm warnings and will work with Airservices (Australia) to determine the best way of communicating the nature of the potential meteorological threats associated with thunderstorms to pilots and controllers.

Last update 03 April 2012