Context : The Banja Luka incident on 28 February 1994, was an incident in which six Republika Srpska Air Force J-21 Jastreb single-seat light attack jets were engaged, and four of them shot down, by United States Air Force F-16 fighters southwest of Banja Luka, Bosnia and Herzegovina. 
Question : On what date did Banja Luka incident occur?
28 February 1994