I read an article years ago in Flying magazine about the "borate bombers" that fight fires in the US. This was when they were still using converted B-17s and the like, piston-engine airplanes.
I remember one comment in the article by a B-17 pilot who said it was not uncommon as they made a run in over a big crowning fire to have all four engines suddenly quit because the fire was sucking all the oxygen out of the air above it. The engines, he said, fired back up after they passed over the burning crown but he said it was always a gut-wrenching feeling.
Provence is plagued with late Summer forest fires, like Southern California, it gets really dry and windy and a small brush fire gets out of control in a hurry. The French keep quite a fleet of these in Marignane, not far from Marseille.
Here's a low-quality pic I took of one practicing near the coast at Antibes a couple of years ago.
There is, or used to be, a DC-10 that did this, too.
Of course the real champions are the Martin Mars flying boats that for years were based on Sproat Lake on Vancouver Island. I think the last two have been pulled out of service fairly recently, however. I heard they had simply become too difficult to keep operational. My wife and I got a tour of one many years ago. Amazing machine given its WWII-era design.
My wife and I toured the Ontario Heritage Bushplane museum a couple years ago in Sault Ste. Marie Ontario and they have many vintage firefighting air craft on display including the first single engine that used just the modified pontoons for water pickup. You are able to get inside most and they have both a simulator and a theatre where it feels like you are actually in the plane. The link below is the pic of the Canadair CL-215 they have on display. Great display if your ever in that neighbourhood.