Which item is explicitly mentioned as necessary in the event of ditching?

Life jackets are explicitly mentioned as necessary in the event of ditching because they provide essential flotation support to passengers and crew when transitioning from an aircraft to water. In drowning scenarios, maintaining buoyancy is critical until rescue can be accomplished. Life jackets are designed to keep individuals afloat and assist with visibility, significantly increasing the chances of survival in water. Their use is a standard safety measure in aviation and is identified as a vital piece of equipment for anyone who may find themselves in a ditching situation.

Other items, while helpful in various emergency scenarios, do not serve the same primary functional purpose of immediate flotation that life jackets do. An emergency blanket, for instance, is used primarily for warmth, while water flotation devices may refer to aids that require manual handling or cannot be readily worn. Safety vests might provide visibility but lack the critical function of buoyancy needed in water. Hence, life jackets stand out as an unequivocal necessity for surviving a ditching event.