The airbourne studies were begun by the United Kingdom's Meteorological office when they traveled to Bahrain with their C-130 aircraft and made eight flights that made measurements in the plume at different points along its axis. The NCAR Electra and University of Washington Corvair continued these measurements with a much more extensive array of instruments. A German aircraft, a Piper Navajo, was also making measurements at that time with a more abbreviated set of instruments. A follow on study was conducted by the Battelle G-1 supported by the department of Energy in July 1991.