To assume a brace position or crash position is an instruction that can be given to prepare for a crash, such as on an aircraft; the instruction to "Brace for impact!" or "Brace! Brace!" is often given if the aircraft must make an emergency landing on land or water. There are many different ways to adopt the brace position, with many countries adopting their own version based on research performed by their own aviation authority or that of other countries. The most common in passenger airliners being the forward-facing seat version, in which the person bracing places their head against or as close as possible to the surface it is likely to strike (and in the process bending over to some degree), placing their feet firmly on the floor, and their hands either on their head or the seat in front.