The International Commission for Air Navigation (ICAN) had already adopted the metric system as a standard for air navigation. The importance of a common system of measurements was realized in 1944 at the Chicago Conference on International Civil Aviation. The PICAO Air Navigation Committee established a Dimensional Practices Committee to address the issue of an universal adoption of a standard method of measurements in civil aviation used between aircraft in flight and ground stations in the exchange of air traffic control instructions and information required for the safe operations of aircraft. Resolution 27 (on the Unification of Numbering and Systems of Dimensioning in connection with International Civil Aviation) of the Interim Assembly of the Provisional International Civil Aviation Organization (PICAO) requested to determine the nature and importance of the handicaps imposed on civil aviation by lack of unification of units of measurement and to recommend the best means of overcoming such handicaps.