If brian survives the crash I’m guessing he will survive but be severely injured. From the crash I think he might have some broken bones in his body. I think he also might scavenge stuff from the ship to help him survive like the axe to chop down trees to make campfires.To keep him warm and also to warn nearby island or planes and boats about his location but if none comes to save him if the cockpit is still intact i think he could use that as shelter. Because he has to try to stay as dry as he can and warm because he has no other clothes to wear so he should try to stay healthy and warm to survive this situation.
Maybe he could make a spear with the wood on the island to go spear fishing for food. Otherwise if the trees are coconut trees he could drink out of those or eat out of them, maybe make them into a cup or bowl if makes a cup with the coconut. And if he fills the cup with sea water and boils it on the fire then he could make fresh water to drink so he stays hydrated. For a bed he could take the cushion from the seats in the cockpit to use as a bed but for a blanket maybe he could find something in the plane that he could use. He should be able to survive some nights but if he doesn’t get found by then he will die.