 In the 1990s, Korean Air became the first airline to use the new McDonnell Douglas MD-11 to supplement its new fleet of Boeing 747-400 aircraft; however, the MD-11 did not meet the airline's performance requirements and they were eventually converted to freighters.Some older 747 aircraft were also converted for freight service.In the 1980s, Korean Air's head office was in the KAL Building on Namdaemunno, Jung-gu, Seoul.