The Korean People's Army Air Force, (Chosŏn'gŭl: 조선인민군 공군; Hanja: 朝鮮人民軍 空軍), is the name of the unified aviation forces of North Korea. The KPAF is the second-largest branch of the Korean People's Army with an estimated 110,000 personnel. It possesses between 1,600 and 1,700 aircraft of different types, mostly of Soviet and Chinese origin. Its primary task is to defend North Korean airspace. When the People's Army was formed up with Soviet help, the aviation unit became its air force branch on August 20, 1947. North Korea has celebrated August 20 as Air Force Foundation Day ever since.