An aerial ladder is a type of ladder designed to extend, without support, to reach high places. This type of ladder is most commonly installed on fire trucks for the purpose of firefighting and rescue. Aerial ladders were first invented in the late 19th century in response to the need for longer ladders to help firefighters reach the upper stories of increasingly tall buildings. The first aerial ladders were made from wood and raised by a system of hand cranks. Modern aerial ladders are made from strong, light materials, like aircraft grade aluminum, and can be quickly raised by means of hydraulics or electric motors.
Most ladders of this type are constructed by combining two or more sections of reinforced ladder in such a way that they nest within each other when retracted. They are much more strongly constructed than a standard ladder, and the sections will often have a box-like profile when viewed from the side, with diagonal cross bracing that may resemble bridge or roof trusses. An aerial ladder is designed to be self-supporting until it reaches its target, and some are capable of remaining free standing in space even with the additional weight of one or more firefighters.
Modern firefighting trucks and vehicles are by far the most common carriers of aerial ladders. These devices are important aids for fighting fires and rescuing people trapped by fires as well as for other rescue operations involving buildings that are more than one or two stories above ground level. Ladder trucks have developed specifically to make use of this invaluable firefighting and rescue tool.
The main use of an aerial ladder is to allow firefighters and other rescue personnel access to high places. Many improvements to the basic idea have expanded its usefulness and effectiveness. An aerial ladder may be outfitted with a platform or bucket on the end, to give firefighters or rescue personnel a stable place from which to perform their duties while high in the air.
Some aerial ladders are equipped with automated systems for water delivery so that firefighters do not have to carry hoses to the top of the ladder. Some may have a fire hose nozzle mounted on a swiveling turret allowing a firefighter to quickly and efficiently aim a stream where it will do the most good. A small integral water tank may be present on some aerial ladders to provide a supply of water when another source, such as a fire hydrant, is not available.