An evaluation by an observer aboard an aircraft in flight of one or more of the following elements: temperature; humidity; wind speed and direction; turbulence; icing; prevailing hydrometeors and lithometeors; the state of the sky; and the height of a specified pressure surface. The observation includes the position and the altitude of the aircraft and time of observation. This term is applied to those in-flight observations that are conducted on a fairly complete and formal basis, such as in aircraft weather reconnaissance. Compare pilot report, apob, aircraft sounding.