A decade ago, a California airship company almost built a prototype of a firefighting airship, but unfortunately went bankrupt in the crash of 2000. But their idea was sound, and hopefully will be built by a different airship company.
Though it sounds improbable on the surface, and airship has some huge advantages over the other firefighting aircraft, fixed wing and helicopter.
The biggest of these is that it can carry a huge payload of water. And because of its hover ability, it does not have to drop it all at once, though it can. Instead, it can “rain” heavy droplets of water over an area, either burning, or in the path of the fire, which is a highly effective means of suppressing a fire.
Likewise, it could descend a fire hose for accurate spray of either water or very high expansion firefighting foam on hotspots.
And instead of having to refill it with hoses, an airship could just set down on a lake, pond, water tank, or other body of water, with its tank inlets open, and rapidly refill its tank.
As the load is lessened, compressors put the extra helium back into storage tanks, and VTOL impulse fans, like on the Goodyear blimp, give it an extra push to take off. Cruising speed about 40mph.
A simple, on board infrared camera can help the airship quickly locate the location of a fire at a distance, by looking for its heat column, and to avoid running into the heat column, though this would likely not be a problem except when a fire turns so intense it becomes a firestorm.
But even then it could use its descending hose and any crosswinds, to offset its water some distance onto the firestorm.
Was that the Heliostat? I remember drawings/prototypes for that.