similar effect to whiteout (the ash will also stick to your windscreen, which will likely be wet from the water pickup). You should really be in a balanced straight line during and after the drop, as it requires a little follow-through. Dropping at some speed over an area is mostly used for cooling purposes after the flames are out, as a fire can stay underground for days. IR is used to detect hotspots afterwards.
In valleys, be aware of the extra power required to get you out of the “hole” with a load on—buckets don't always release their load, especially if the connectors get wet when picking up.
Checks for your bucket include the cargo arming switch, bucket open and close switch and electrical and mechanical jettison, and the capacity (for performance). Don’t forget the mirror and cables, as you would with
any slung load.
Forest and moorland fires also require vast amounts of manpower, which are usually tired by the time they get to the fire from the long walk to get there, so you may be used as transport for fire-fighters and their equipment, as well as observation, where your passengers will
have some rank and experience, since they will be directing ground forces from the air (this will be especially true for lesser-powered helicopters). Very often, you will be moving people in very short hops over rivers and streams.
One development of this is rappelling, which is the rapid deployment of fire crews by rope from a helicopter (and back in emergency) until the regular crews arrive. This saves them the trek to the fire in the first place and ensures they are not exhausted when they start. They can survive for up to 48 hours in the bush, and a Command Spotter will stay in the helicopter. All this will typically be for fires started by lightning, which are often in remote locations, down to weather conditions roughly equivalent to Special VFR.

 Rappelling shouldn’t be done when it’s too windy, or when it’s raining, as the special rope used will swell up in the pulleys and stop working (just for interest, lightning can be up to 50,000° in temperature – when it hits a tree, the sap boils and the heat can be held internally for days until fire actually breaks out).
You will also not necessarily be the only aircraft about. The combination of lots of smoke (and poor visibility), coupled with heat turbulence and other machines buzzing about could prove to be extremely dangerous – many people report it’s just like being in a war zone (the organised chaos only makes it more so), but if you've ever done the British Grand Prix or joined Biggin Hill circuit you should be alright. Constant communications between machines (on the same frequency) are essential, especially if you are picking up from the same swimming pool (in practice, you will go through the bird dog if you want to change position). One pilot reported that the distance from a pond to the fire was so small as to only require a fast hover taxi between them both, which meant that oil temperatures began to redline, as there wasn’t enough airflow to cool things down (sometimes ash will clog the oil cooler). You will be tired, as well, after a couple of days' continuous flying from dawn to dusk, though you won’t notice till afterwards, as adrenalin counts for a lot.