Most countries have one or more services funded by the government or by the public, which provide help for people in danger from natural disaster or other kinds of life threatening accidents. Such services have a variety of marine and land vehicles at their disposal, and depending on their local environment. Air cushioned vehicles, or hovercraft as they are commonly known, can provided a flexibility not matched by other modes of transport.
Imagine a plane crash somewhere over the Russian steps. Thee weather is bad and the visibility over 1000 feet is very bad, with strong gusting winds. The terrain is sometimes frozen and sometime marshy, making it very difficult for a wheeled vehicle to navigate. A helicopter couldn't get close in those conditions and ground vehicles have been ruled out. Why not use an ACV that floats about a foot over the ground? Marshy and icy surfaces mean nothing to a vehicle that rises above them, so it's a perfect choice.
Many locations are next to lakes or large bodies of water. Of course, rescue operations for these locations will already have boats ready to do the job, but what about a northern clime in winter time? A boat would simply not do the job in the northern end of Lake Michigan when ice covers much of the surface area. In this situation, a hovercraft would be ideal and many rescue team leaders are starting to realize this and more than makes up for the cost of buying a hovercraft
Survey exploration of vast territories is another situation where an air cushioned vehicle can perform well. It's not sure that any studies have been done to ascertain the economic virtues, but it's certain that hovercraft manufacturers will have the right information to hand. Marine craft and small boats tend to use two stroke engines, which run on a mixture of petrol and oil. In this way, they don't need a separate oil reservoir, so there is a small cost saving here. On the downside, they are less smooth than a four stroke engine.
The four stroke petrol engine is generally quieter, particularly if water cooled, because the engine is surrounded by a water jacket. A powerful four stroke motor can easily provided both upward and forward thrust through a system of ducts which separate the air flow to the area under the skirt and behind the craft. Larger hovercraft would need more than one engine of course, but a small single engined version could rapidly travel to an accident site and bring back two or more accident victims.