One argument states that water drops, falling three thousand feet as at Victoria Falls, break up into mist and never hits the ground.

Another states that rain drops would be vaporized by the heat before they landed and that forest fires are best doused from @300 ft.above the flames from a plane.

I propose that the airship be equipped with an Ice/Snow Ball Machine that is extremely efficient at 10,000 feet elevation. It converts all the water into a hold full of ice balls. This can also put a protective ice coating on the lower exterior skin, to advantage for once.

It's one of those airships that has a ballast near ground level and the airship rises and winches down on cables when its cargo weight changes to avoid gas release.

This lower ballast also has a heat resistant exterior coating, (tiles), allowing it to be within a thousand feet of the flames thereby dropping ice balls and then water to bring the fire core down to below 454 degrees spontaneous combustion temperature.

This could also be used to freeze breeding pine beetles by smothering a forest with these frozen balls for a few weeks but I guess that's climate control and something different.

[World] could probably find other uses for this idea.