Complex sentence: On December 7, while Hendrix and Levine were travelling by limousine to a New York airport for their flight to Toronto, Levine noticed that Hendrix was putting some personal items into his guitar case.
Split into simpler sentences: On December 7, Hendrix and Levine travelled by limousine to a New York airport. While en route, Levine noticed that Hendrix was putting some personal items into his guitar case.