The Australian Implementation of AMDAR/ACARS (Aircraft Meteorological Data Relay/ARINC Communications Addressing and Reporting System) and the Use of Derived Equivalent Gust Velocity as a Turbulence Indicator,

AMDAR Aircraft Meteorological Data Relay is a system of measuring wind speed, wind direction, air temperature and an indication of turbulence from INS-equipped transport aircraft in flight. These data are transmitted by radio to the meteorological data system. This report outlines the Autstralian AMDAR system presently coming into service on the Boeing 767 aircraft in the Ansett fleet. The data are telemetered using ACARS and the SITAAIRCOM network of ground stations. The ACARS is a digital HFVHF link carrying communications both ways between an aircraft and a special network of ground stations. Outside the U.S.A. the network is operated by SITA and is called the AIRCOM network. Particular attention is paid to the indicators of turbulence. Because an aircraft flying through a given gust may encounter very different vertical accelerations depending on aircraft mass, airspeed and altitude, it is proposed that the AMDAR system compute the derived equivalent gust velocity from the aircraft acceleration and other parameters, and that this be used as an indicator of turbulence. Severe turbulence corresponds to derived equivalent gust velocities in excess of 9 ms. Keywords Aviation meteorology, Wind, Gusts, Wind shear, Data acquisition, INSInertial Navigation Systems, Australia.