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ABS (Antilock Braking System): Computer, sensors and solenoid valves which together monitor wheel speed and modulate braking force if wheel lockup is sensed during braking. This helps the driver retain control of the vehicle during heavy braking on slippery roads.

Able-Bodied Seaman: A member of the deck crew who is able to perform all the duties of an experienced seaman; certificated by examination; must have three years sea service.

Above Ground Level: Distance of the aircraft above the ground.

Above Sea Level: Distance of the aircraft above mean sea level.

Acceptance Flight: A flight made to accept a contractor-produced aircraft, or one on which a contractor or Army depot has performed maintenance or contract modification before return to the operational inventory It can also be a flight made by the receiving unit upon transfer of aircraft between components and/or units. Active Duty Guard/Reserve (AGR) Guard members and Reservists on full-time active duty for periods of 180 days or more to provide full-time support to the Reserve Components.

Act Of God: An extraordinary and unexpected natural event, such as a hurricane, tornado, earthquake or even the sudden death of a person. An act of God may be a defense against liability for injuries or damages. Under the law of contracts, an act of God often serves as a valid excuse if one of the parties to the contract is unable to fulfill his or her duties.

Adhesion: The grip of the driving wheels of a locomotive obtained on the rail, particularly important when starting. The weight on the driving wheels is particularly helpful in this respect.

Adhesive Factor: The ratio of maximum tractive effort, expressed in pounds, to the adhesive weight, also in pounds, of a locomotive. It will usually be about 25% of the adhesive weight for a locomotive with two or four cylinders. For a locomotive with three cylinders, the adhesive factor might be reduced to 3.5 to 1.

Adhesive Weight: The adhesive weight is that part of the locomotive weight carried on the driving wheels which can therefore contribute towards adhesion.

Administrative Law Judge: A representative of a government commission or agency vested with power to administer oaths, examine witnesses, take testimony, and conduct hearings of cases submitted to, or initiated by, that agency.

Admission, Steam: In steam engine operation, the period during which the steam valve exposes the steam port to allow live steam to enter the cylinder. The admission period is restricted to a percentage of the piston stroke.

Affidavit: A written statement under oath.

AFV (Alternative Fueled Vehicle): Vehicle powered by a fuel other than gasoline or diesel.

Agreement: Mutual assent between two or more parties; normally leads to a contract; may be verbal or written.

Air Brake: Standard train brake originating in the US using compressed air in which the control is actuated from a driver’s brake valve. A fall in brake pipe air pressure causes a brake application on each vehicle whilst a restoration of pressure causes the brake to release. A triple valve on each vehicle monitors the pressure in the brake pipe. When pressure falls, the distributor allows air from an auxiliary reservoir on the vehicle to pass to the brake cylinders to apply the brake. When pressure rises, the triple valve releases the air from the brake cylinder and recharges the auxiliary reservoir for the next application, using air from the brake pipe as it recharges.

Air Ride Suspension: Suspension which supports the load on air-filled rubber bags rather than steel springs. Compressed air is supplied by the same engine-driven air compressor and reservoir tanks which provide air to the air brake system.

Air Traffic Incident Report: Report on incidents that adversely affect the FAA air traffic service facilities in providing safe, orderly, and expeditious movement of air traffic. This report is usually prepared by FAA on FAA Form 8020-11.

Airplane: An engine-driven fixed-wing aircraft heavier than air that is supported in flight by the dynamic reaction of the air against its wings.

Alleged Violations: Those infractions of applicable FAA, (ICAO), and host country flight regulations that create an unsafe condition or result in an incident or accident.

Answer: Pleading filed by the defendant that responds to a complaint, petition, or motion.

Appeal: A request to the higher court for review of the lower court’s decision and to request a reversal of the judgment.

Arbitration: The procedure by which a dispute may be resolved by a person who is not a judge. Arbitration is often used to limit legal costs to both parties.

Arbitrator: A person who conducts an arbitration.

Articulated Locomotive: A locomotive where two engines (sets of cylinders, valve gear and wheels) were provided under the same frame but pivoted to allow transition through curves in spite of the long wheelbase. Garratt and Mallet were two types of articulated locomotives. Much favoured in Africa, India and the US but not common in Europe and the UK. Some locomotives built to Fairlie's patent also had two engines but not all were articulated.

ASAT (Anti-Satellite): ASAT missions are related to the development of vehicles used to destroy orbiting satellites. This category includes the ASAT interceptors themselves, as well as vehicles placed into orbit as test targets.

Assumption Of Risk: A doctrine that states if the plaintiff has knowingly accepted the danger of doing something, recovery from the defendant in an action brought for negligence will be barred.

Atlantic Type Locomotive: Name given to the 4-4-2 type of locomotive, originally derived either from the locomotives of the Philadelphia Railroad which ran between Camden and Atlantic City NJ or from the group of this type built for the Atlantic Coast Railroad. The type was first introduced in the US in 1888 for the Lehigh Valley RR and in UK on the GNR in 1898 to a design by H.A. Ivatt.

ATV (All Terrain Vehicles): Vehicle designed for any type of terrain.

Automatic Train Stop System: A system actuated by wayside inductors, so arranged that its operation will automatically result in the application of the brakes until the train has been brought to a stop.

Aviation Law: The branch of law that covers aspects of air transportation, including passenger air travel, air freight shipping, airspace rights of way, and aircraft operation and maintenance. By its very nature, aviation law involves interplay of international law, federal statutes and regulations, and state and federal tort law. While most tort law is regulated at the state level, in the event of an airline crash or other aviation-related incident, the Federal Aviation Administration and Federal Aviation Administration and National Transportation Safety Board regulations take precedence over state law, making aviation law different from other personal injury law.

Aviation Officer: An Army or DA civilian aviator who commands an aviation unit or is a member of a commander's staff and advises or supervises Army aviation functions.

AVL (Automated Vehicle Location): Class of technologies designed to locate vehicles for fleet management purposes and for stolen vehicle recovery. Infrastructure can be land-based radio towers or satellites.

Axle: Structural component to which wheels, brakes and suspension are attached.