The red life jacket is an example of an air chamber vest.
Life jackets for outfitting large commercial transport in potentially dangerous waters, such as coastal cruises and offshore passages, and overwater air flights, are often a pair of (twin or double) sealed air chambers constructed of coated nylon (sometimes with a protective outer encasing of heavier, tougher material such as vinyl), joined together (but can also be constructed of foam aboard ships). Twin air chambers provide for redundancy in the event of one of the air chambers leaking, for example if the thin air cell fabric is sliced open by sharp metal fragments during emergency evacuation and egress.
Aircraft devices for crew and passengers are always inflatable since it may be necessary to swim down and away from a ditched or submerged aircraft: inflated or foam filled devices would significantly impede a person from swimming downward in order to escape a vehicle cabin. Upon surfacing, the person would then inflate the device, orally or by triggering the gas canister release mechanism.
"True" Life Jackets always provide more buoyancy than buoyancy aids1 and the positioning of the buoyancy on the wearer's torso is such that a righting moment (rotational force) is developed that will eventually float most persons (for example unconscious) who are face down into a FACE UP attitude with their bodies inclined backward, unlike common foam buoyancy vests (which are simply swimmers' aids, really since they don't generate re-righting moment forces.) Self righting devices are be best for non-swimmers2, who may not be able to orient themselves face up in the water, for example due to panic arising from finding themselves in deep, open water.
Today these air chamber vests are commonly referred to as "Inflatable Life Jackets or Vests" and are available not only for commercial applications but also for recreational boating, fishing, sailing, as well as kayaking and canoeing. They are available in a variety of styles and are generally more comfortable and less bulky than traditional foam vests.
The air chambers are always located over the breast, across the shoulders and encircling the back of the head. They may be inflated by either self-contained carbon dioxide cartridges activated by the pulling of a cord, or blow tubes with a one-way valve for inflation by exhalation. Some of the inflatable life jackets also react with the salt/fresh water, inflating them. The latest generation of self triggering inflation devices3, however, respond to water pressure when submerged and incorporate an actuator known as a "hydrostatic release". Regardless of whether manually (pull cord) or automatically triggered, a pin punctures the cartridge/canister and the CO2 gas escapes into the sealed air chamber.
Drifting in open seas and international waters, as encountered by long sea voyages and military forces, require prolonged survival in water. The life jackets suited for this purpose are often attached to a vest with pockets and attachment points for distress signaling and survival, for example: a handheld two-way radio (walkie-talkie), emergency beacon (406 MHz frequency), signal mirror, sea marker dye, smoke or light signal flares, strobe light, first-aid supplies, concentrated nutritional items, water purification supplies, shark repellent, knife, pistol.
Offshore sailors and others can utilize accessories such as leg straps to keep the inflated chambers in position for floating in a stable attitude and splash or face shields constructed of clear see-through vinyl which covers the head and face to ward off water from waves inundating the face (nasal and mouth entries to the airway).
