Engine failure

Although aircraft are now designed to fly even after the failure of one or more aircraft engines, the failure of the second engine on one side for example is obviously serious. Losing all engine power is even more serious, as illustrated by the 1970 Dominican a DC-9 air disaster, when fuel contamination caused the failure of both engines. To have an emergency landing site is then very important.

In the 1983 Gimli Glider incident, an Air Canada flight suffered fuel exhaustion during cruise flight, forcing the pilot to glide the plane to an emergency dead stick landing. The automatic deployment of the ram air turbine maintained the necessary hydraulic pressure to the flight controls, so that the pilot was able to land with only a minimal amount of damage to the plane, and minor (evacuation) injuries to a few passengers.

The ultimate form of engine failure, physical separation, occurred in 1979 when a complete engine detached from American Airlines Flight 191, causing damage to the aircraft and loss of control.

Navigation aids and instrument flight

One of the first navigation aids to be introduced (in the USA in the late 1920s) was airfield lighting to assist pilots to make landings in poor weather or after dark. The Precision Approach Path Indicator was developed from this in the 1930s, indicating to the pilot the angle of descent to the airfield. This later became adopted internationally through the standards of the International Civil Aviation Organization (ICAO).

With the spread of radio technology, several experimental radio based navigation aids were developed from the late 1920s onwards. These were most successfully used in conjunction with instruments in the cockpit in the form of Instrument landing systems (ILS), first used by a scheduled flight to make a landing in a snowstorm at Pittsburgh in 1938. A form of ILS was adopted by the ICAO for international use in 1949.

Following the development of radar in World War II, it was deployed as a landing aid for civil aviation in the form of Ground-controlled approach (GCA) systems, joined in 1948 by distance measuring equipment (DME), and in the 1950s by airport surveillance radar as an aid to air traffic control. VHF omni directional range (VOR) became the predominate means of route navigation during the 1960s superseding the Non-directional beacon (NDB). The ground based VOR stations were often co-located with DME, so that pilots could know both their radials in degrees with respect to north to, and their slant range distance to, that beacon.

Air safety

Air safety is a term encompassing the theory, investigation and categorization of flight failures, and the prevention of such failures through regulation, education and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel.
In most countries, civil aircraft have to be certified by the Civil Aviation Authority (CAA) to be allowed to fly. The major aviation authorities worldwide are the US Federal Aviation Administration (FAA) the European Aviation Safety Agency (EASA) (which provides regulatory advice to the European Union and to a degree supplanted the regulatory bodies of member countries). FAA and EASA are, in particular, primarily responsible for the certification of the airliners from the two major manufacturers, Boeing and Airbus.

Aircraft are certified against guidelines set out in the code for each CAA. Those codes are very similar and differ primarily in equipment and environmental standards. Regulations on maintenance, repair and operation provide further direction to the owners of the aircraft so that the aircraft continues to meet design standards.

Spacecraft

A spacecraft is a craft or machine designed for spaceflight. On a spaceflight, a spacecraft enters space then returns to the Earth. For an orbital spaceflight, a spacecraft enters a closed orbit around the planetary body. Spacecraft used for human spaceflights carry people on board as crew or passengers. Spacecraft used for robotic space missions operate either autonomously or telerobotically. Robotic spacecraft that leave the vicinity of the planetary body are space probes. Robotic spacecraft that remain in orbit around the planetary body are artificial satellites. Starships, which are built for interstellar travel, are so far a theoretical concept only.

Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and space tourism. Spacecraft and space travel are common themes in works of science fiction.