Inertial navigation system in the context of "Attitude and heading reference system"

In navigation, dead reckoning is the process of calculating the current position of a moving object by using a previously determined position, or fix, and incorporating estimates of speed, heading (or direction or course), and elapsed time. The corresponding term in biology, to describe the processes by which animals update their estimates of position or heading, is path integration.

Advances in navigational aids that give accurate information on position, in particular satellite navigation using the Global Positioning System, have made simple dead reckoning by humans obsolete for most purposes. However, inertial navigation systems, which provide very accurate directional information, use dead reckoning and are very widely applied.

An accelerometer is a device that measures the proper acceleration of an object. Proper acceleration is the acceleration (the rate of change of velocity) of the object relative to an observer who is in free fall (that is, relative to an inertial frame of reference). Proper acceleration is different from coordinate acceleration, which is acceleration with respect to a given coordinate system, which may or may not be accelerating. For example, an accelerometer at rest on the surface of the Earth will measure an acceleration due to Earth's gravity straight upwards of about g ≈ 9.81 m/s. By contrast, an accelerometer that is in free fall will measure zero acceleration.

Highly sensitive accelerometers are used in inertial navigation systems for aircraft and missiles. In unmanned aerial vehicles, accelerometers help to stabilize flight. Micromachined micro-electromechanical systems (MEMS) accelerometers are used in handheld electronic devices such as smartphones, cameras and video-game controllers to detect movement and orientation of these devices. Vibration in industrial machinery is monitored by accelerometers. Seismometers are sensitive accelerometers for monitoring ground movement such as earthquakes.

An anti-ship missile (AShM or ASM) is a guided missile that is designed for use against ships and large boats. Most anti-ship missiles are of the sea-skimming variety, and many use a combination of inertial guidance and active radar homing. A large number of other anti-ship missiles use infrared homing to follow the heat that is emitted by a ship; it is also possible for anti-ship missiles to be guided by radio command all the way.

Many anti-ship missiles can be launched from a variety of weapons systems including surface warships (also referred to as ship-to-ship missiles), submarines, bombers, fighter planes, patrol planes, helicopters, shore batteries, land vehicles, and, conceivably, even infantrymen firing shoulder-launched missiles. The term surface-to-surface missile (SSM) is used when appropriate. The longer-range anti-ship missiles are often called anti-ship cruise missiles. Several countries are also developing anti-ship ballistic missiles.

Fire-and-forget is a type of missile guidance which does not require further external intervention after launch such as illumination of the target or wire guidance, and can hit its target without the launcher being in line-of-sight of the target. This is an important property for a guided weapon to have, since a person or vehicle that lingers near the target to guide the missile (using, for instance, a laser designator) is vulnerable to attack and unable to carry out other tasks.

Generally, information about the target is programmed into the missile just prior to launch. This can include coordinates, radar measurements (including velocity), or an infrared image of the target. After it is fired, the missile guides itself by some combination of gyroscopes and accelerometers, GPS, onboard active radar homing, infrared homing optics, and anti-radiation homing. Some systems offer the option of either continued input from the launch platform or fire-and-forget.

Area navigation (RNAV, usually pronounced as /ˈɑːrnæv/) is a method of instrument flight rules (IFR) navigation that allows aircraft to fly along a desired flight path, rather than being restricted to routes defined by ground-based navigation beacons.

The acronym RNAV originally stood for "random navigation," reflecting the initial concept of flexible routing, though the term now refers to a precisely defined and controlled method. This flexibility enables more direct routes, potentially saving flight time and fuel, reducing congestion, and facilitating flights to airports lacking traditional navigation aids. RNAV achieves this by integrating information from various navigation sources, including ground-based beacons (station-referenced navigation signals), self-contained systems like inertial navigation, and satellite navigation (like GPS).

The BGM-109 Tomahawk Land Attack Missile (TLAM) is an American long-range, all-weather, jet-powered, subsonic cruise missile that is used by the United States Navy, Royal Australian Navy, Royal Netherlands Navy and Royal Navy in ship and submarine-based land-attack operations.

Developed at the Applied Physics Laboratory of Johns Hopkins University under James H. Walker near Laurel, Maryland, the Tomahawk emerged in the 1970s as a modular cruise missile first manufactured by General Dynamics. Early tests of the missile took place between 1983 and 1993, during which time 23 cruise missiles were tested over northern Canada under the "Canada–U.S. Test and Evaluation Program". The goal of the program was to simulate the climate and terrain similar to that of the northern Soviet Union, and to allow the North American Aerospace Defence Command (NORAD) to develop an anti-cruise capability. The Tomahawk aimed to fulfill the need for a medium- to long-range, low-altitude missile with diverse capabilities. Its modular design allows for compatibility with a range of warheads, including high-explosive, submunitions, and bunker-busters. The Tomahawk can use a variety of guidance systems, including GPS, inertial navigation, and terrain contour matching. Over a dozen variants and upgraded versions have been developed since the original design, including air-, sub-, and ground-launched configurations with both conventional and nuclear armaments. The Tomahawk's manufacturing history has seen several transitions. General Dynamics served as the sole supplier in the 1970s. From 1992 until 1994, McDonnell Douglas was the sole supplier of Tomahawks, producing Block II and Block III versions and remanufacturing many Tomahawks to Block III specifications. In 1994, Hughes Aircraft, having purchased General Dynamics' missile division in 1992, outbid McDonnell Douglas to become the sole supplier of Tomahawks. A joint venture between Hughes and Raytheon manufactured the missile from 1995 until Raytheon's acquisition of Hughes in 1997, solidifying their position as the sole supplier. In 2016, the US Department of Defense purchased 149 Tomahawk Block IV missiles for $202.3 million. As of 2024, Raytheon remains the sole manufacturer of non-nuclear, sea-launched Tomahawk variants.

Spacecraft flight dynamics is the application of mechanical dynamics to model how the external forces acting on a space vehicle or spacecraft determine its flight path. These forces are primarily of three types: propulsive force provided by the vehicle's engines; gravitational force exerted by the Earth and other celestial bodies; and aerodynamic lift and drag (when flying in the atmosphere of the Earth or other body, such as Mars or Venus).

The principles of flight dynamics are used to model a vehicle's powered flight during launch from the Earth; a spacecraft's orbital flight; maneuvers to change orbit; translunar and interplanetary flight; launch from and landing on a celestial body, with or without an atmosphere; entry through the atmosphere of the Earth or other celestial body; and attitude control. They are generally programmed into a vehicle's inertial navigation systems, and monitored on the ground by a member of the flight controller team known in NASA as the flight dynamics officer, or in the European Space Agency as the spacecraft navigator.

An inertial platform, also known as a gyroscopic platform or stabilized platform, is a system using gyroscopes to maintain a platform in a fixed orientation in space despite the movement of the vehicle that it is attached to. These can then be used to stabilize gunsights in tanks, anti-aircraft artillery on ships, and as the basis for older mechanically based inertial navigation systems (see Inertial measurement unit).