Complex sentence: The plane, a Bombardier CRJ200, was at an altitude of when it came dangerously close to the drone, described by one of the pilots "as a camouflaged F-4 fixed-wing aircraft that was quite small".
Split into simpler sentences: The plane, a Bombardier CRJ200, was at an altitude of. The drone was described by one of the pilots "as a camouflaged F-4 fixed-wing aircraft that was quite small".