Complex sentence: Lin's plane initially traveled southeast (in the directions of Guangzhou), but returned twenty minutes later and circled the airport several times as if it were trying to land, but the runway lights had been turned off.
Split into simpler sentences: Lin's plane initially traveled southeast (in the direction of Guangzhou). The plane then returned twenty minutes later and circled the airport several times as if it were trying to land, but the runway lights had been turned off.