"The flight had taken off at approximately 6:06 p.m., destined for Tijuana, Mexico, with a scheduled stop in Missouri."
Based on some other things I’ve seen, I believe the pilots lost Situational Awareness when they enter the clouds. Vertigo. When My instructor ‘gave’ it to me one night I started a descending left hand turn. Once he ‘saved’ it, I wanted to puke. That would explain the powered dive.