Complex sentence: In the late 1970s Air Illinois operated the 44-passenger Hawker Siddeley HS 748 turboprops into at Meigs, which was the largest aircraft to use it on a regular basis for scheduled passenger airline operations.
Split into simpler sentences: In the late 1970s Air Illinois operated 44-passenger seat Hawker Siddeley HS 748 turboprops into at Meigs. The HS 748 was the largest aircraft to use Meigs on a regular basis for scheduled passenger airline operations.