General aviationGeneral aviation (GA) is defined by the International Civil Aviation Organization (ICAO) as all civil aviation aircraft operations except for commercial air transport or aerial work, which is defined as specialized aviation services for other purposes. However, for statistical purposes, ICAO uses a definition of general aviation which includes aerial work. General aviation thus represents the "private transport" and recreational components of aviation.
Rocket-powered aircraftA rocket-powered aircraft or rocket plane is an aircraft that uses a rocket engine for propulsion, sometimes in addition to airbreathing jet engines. Rocket planes can achieve much higher speeds than similarly sized jet aircraft, but typically for at most a few minutes of powered operation, followed by a gliding flight. Unhindered by the need for oxygen from the atmosphere, they are suitable for very high-altitude flight. They are also capable of delivering much higher acceleration and shorter takeoffs.
Commercial aviationCommercial aviation is the part of civil aviation that involves operating aircraft for remuneration or hire, as opposed to private aviation. Commercial aviation is not a rigorously defined category. All commercial air transport and aerial work operations are regarded as commercial aviation, as well as some general aviation flights. Commercial air transport is defined as an aircraft operation involving the transport of passengers, cargo or mail for remuneration or hire. It includes scheduled and non-scheduled air transport operations.
List of diving hazards and precautionsDivers face specific physical and health risks when they go underwater with scuba or other diving equipment, or use high pressure breathing gas. Some of these factors also affect people who work in raised pressure environments out of water, for example in caissons. This article lists hazards that a diver may be exposed to during a dive, and possible consequences of these hazards, with some details of the proximate causes of the listed consequences.
Medium tankA medium tank is a classification of tanks, particularly prevalent during World War II which represented a compromise between the mobility oriented light tanks and the armour and armament oriented heavy tanks. A medium tank's classification is not actually based on weight, but off of tactical usage and intended purpose; for instance the German Panzerkampfwagen V Panther medium tank has a mass similar to contemporary Allied heavy tanks.
Diving physicsDiving physics, or the physics of underwater diving is the basic aspects of physics which describe the effects of the underwater environment on the underwater diver and their equipment, and the effects of blending, compressing, and storing breathing gas mixtures, and supplying them for use at ambient pressure. These effects are mostly consequences of immersion in water, the hydrostatic pressure of depth and the effects of pressure and temperature on breathing gases.
