Jump on a Hippogryph when Tobias signals you and destroy the Horde Gunship.
Gunship destroyed
Description
We need to get rid of that flying gunship if our people have any chance of escaping.
Here's the plan. Keel Harbor had its share of rebel sympathizers in the old days. I've managed to round up a hefty amount of incendiary explosives from one of our storehouses.
We're going to hit the enemy with a force small enough to fly undetected. The night elf hippogryphs should do the trick.
Tobias will give you the signal when we're ready to go.
Progress
The only risks worth taking are the ones that lead to victories worth having.
Completion
We did it, <name>. We've started the evacuation. If we leave soon we'll leave the Forsaken fleet in the dust.
The gunship finally reaches its destination: the ruined Greymane Wall! The explosives go off right as it's about to fly into the wall, obliterating everything in the area. The party escapes on wyverns roosting on the lower deck, heading back to Keel Harbor.
It appears that Korm Bonegrind will more reliably spawn when all the mobs are killed below deck.
Talk to Admiral Nightwind on deck of the night elf ship for the next quest, provided you are ready to depart Gilneas.