A profile of the jet stream, 9th August, 1953

An analysis is made of 'in-flight' winds, obtained at short intervals by a jet aircraft flying across the jet stream on the 9th August, 1953. The extremely erratic in-flight winds are considered to arise from (a) poor position fix determination (b) a combination of unduly short time interval between fixes and high true air speed (T.A.S.) of observing aircraft. Position fixes are critically examined and those considered unreliable are rejected. Winds which are finally selected to establish a jet stream profile of limited detail are those computed, as far as possible, between good fixes over, an optimum time interval of about 15 minutes. A study of the sources of error involved in position fixing indicates that the requirement, for a detailed profile, of accurate winds at short time intervals, cannot be obtained at present by radio compass and distance measuring equipment. Reference is made to jet profile studies overseas, in which a vertical camera is used to obtain location.