International Civil Aviation Organisation (ICAO) recognizes the importance of improving communications between pilots and air traffic controllers in order to avoid accidents. Accordingly, pilots and air traffic personnel must be proficient in English and be able to demonstrate a minimum English Language Proficiency of ICAO Level 4 (Operational Level) according to the ICAO Proficiency Rating Scale in order to be fully licensed internationally.

            In compliance with the Regulation of the Department of Civil Aviation (now the Civil Aviation Authority of Thailand: CAAT) on the Language Proficiency of the license holders, the Department of Civil Aviation, whose primary governmental function and duty is to ensure maximum safety for air travel, authorized Civil Aviation Training Center to be the official ICAO Language Proficiency Center effective official ICAO Language Proficiency Testing Center effective April 2011. The main responsibilities for CATC Language Proficiency Testing Center (CATC-LPTC) are to conduct the test and rate the ICAO Language Proficiency of Test Takers.