Complex sentence: Air 2000 was a British charter airline that operated for 17 years between 1987 and 2004 as Air 2000 and 2004-2008 as First Choice Airways until TUI merged with First Choice Plc First Choice Airways (Previously Air2000) was merged into Thomsonfly.
Split into simpler sentences: Air 2000 was a British charter airline that operated for 17 years between 1987 and 2004. The airline was renamed as First Choice Airways in 2004 which lasted until TUI merged with First Choice Plc in 2008 which as a result First Choice Airways (Previously Air2000) was merged into Thomsonfly.