Complex sentence: McDonald found Lt Kermit A. Tyler, the junior officer in charge at the barely operational warning information center at Pearl Harbor, and indicated that a large number of planes were coming in from the north and that he never received a call like this before.
Split into simpler sentences: McDonald found Lt Kermit A. Tyler, the officer in charge at the barely operational warning information center at Pearl Harbor. He informed Tyler a large number of planes were coming in from the north and he had never received a call like this before.