We know that the pilot knows the area.  He flew that same aircraft as a charter for other celebs, including Kylie Jenner who lives in Calabassas.     I can't imagine making the turn he did in foggy weather... unless there was a mechanical issue. He was following the 101 freeway and could have made it to Thousand Oaks (his destination) in a couple of minutes, but he veers off into the hillside??  Anyone who knows that area knows that you'd risk flying into the Malibu mountain, just west of Calabassas.