here's more info i got from wikipedia.
The duo was formed in late 1998 by SM Entertainment. Brian Joo auditioned while he was attending Holy Spirit High School in New Jersey. Hwang Yoon-Suk, later to be known as Fany, was encouraged to audition by a staff member working for the label at his high school festival. Fly to the Sky officially debuted on November 21, 1999 at the LOG-IN H.O.T. Concert and SM Festival Concert '99.
Soon after, the duo released their debut album Day by Day on December 9, 1999, and made their first official television appearance two days later. Unlike their predecessors on their label, popular teen idols at that time, they shied away from upbeat techno and dance music, opting for mid-tempo ballads. The debut became highly successful selling over 250,000 copies.[4] The duo acquired status as the next-generation stars as they won Best New Artist award in 2000.[3] At the same time, the duo failed to rise to instant stardom unlike their predecessors such as H.O.T., whose album sales have passed the one million mark.[5]
Their popularity slowly climbed with the release of their second album The Promise in 2001, which featured more diverse genres than its predecessor. With more upbeat tracks, it peaked at #2, but quickly disappeared from the charts.[6] In the same year, they held a joint concert with Korean R&B singer Kim Jo-Han.
credit to:
http://en.wikipedia.org/wiki/Fly_to_the_Sky