This paper contains the explanation of the assessment process of the high-stake test for pilots and ATCOS (air traffic controllers) in Uzbekistan. Aviation Training center of Uzbekistan Airways developed and implemented ELPAT (English Language Proficiency Aviation Test) to assess English language proficiency as an integral component to ensure flight safety. The testing system provides opportunities to give valid and reliable assessment in accordance with ICAO (International Civil Aviation Organization) requirements. The paper demonstrates not only the technology how the assessment conducted but also explains the background of the assessment in aviation and the raters(evaluators).