Speak with Khaliisi at the foot of the mountain east of the Grom'arsh Crash-Site.
In order to track down Brann, we're going to need a creature with a keen sense of smell and a good tracking ability. There weren't any hounds on the zeppelin, but I think I have a substitute.
After the crash, I sent Khaliisi down the east face of the mountain to start hunting for food. Her cat, Frostbite, excels at tracking prey in the snow. Tell her that she'll have to part with her companion for a while, at least. She can hunt on her own, but we have no other way of catching up to Brann Bronzebeard.