Aerosondes moved from development to operations in 1998. Operational trials and field programs have been conducted in Australia, Canada and the South China Sea during the first half of the year and further missions are planned in the North Atlantic, Malaysia and Hawaii during the second half.
From January to May, Aerosondes flew 360 h, included 5 missions of >24 h endurance in a wide variety of conditions and aviation regions. These endurance. Operations were conducted in a wide range of atmospheric conditions including sea breezes, frontal systems, the perifery of a tropical cyclone, a severe microburst and serial soundings through a squall-line.
An unplanned flight through a severe microburst provides one indication of the capacity to take in situ observations in conditions that would be impossible for any other observing system. At Port Hedland an Aerosonde was conducting missions in a region of strong vertical shear at the top of a sea breeze layer when it encountered a wet microburst. Subjective estimates were of winds in excess of 35 ms-1 at the surface and the control building, a demountable weighing in excess of 1 tonne with four people inside, was slewed around and moved approximately 1 m before it was arrested by a cable. The Aerosonde initially flew into a downdraft of around 12 ms-1, with descent to an altitude of 250 m, where it entered the microburst head with peak lateral acceleration exceeded 4g and a 30 ms-1 speed change in 1.5 s.
These missions have provided a solid base of experience for future operations. The operational aspects and plans are presented in a separate talk by Holland et al. This talk will provide examples of flights through a variety of weather conditions to indicate the Aerosonde's capacity and limitations for gathering data in the field.