A micro air vehicle is a remote-controlled, unmanned aircraft vehicle (UAV) significantly smaller than typical UAVs. For instance, the Predator drone, considered a standard UAV as of 2008, is about 8.22 m (27 ft) in length. Micro air vehicles are much smaller, as much as a foot or so in diameter, but preferably smaller, 6 inches in diameter or less. Micro air vehicles promise to revolutionize warfare, and many operate on the same general principles of flight as birds or insects do, being of similar size.
Micro air vehicles are currently in the development stage -- there aren't really any micro air vehicles that are deployed on the battlefield and used regularly, except for some small reconnaissance airplanes. Most people working on micro air vehicles are doing so for the military, usually the US military. The goal is to create craft less than six inches in diameter which can hover, navigate through tight urban environments, and have the capability of perching, all while sending data to a ground team. This would be invaluable to military operations, where up-to-the-minute recon information can be a matter of life or death.
Although not discussed as frequently, micro air vehicles, when actually developed enough that they can actually be deployed, are likely to be used for combat as well. This use would be similar to the tracked SWORDS robotic system which can be mounted with a machine gun and instructed to fire on enemy combatants. Micro air vehicles mounted with a small handgun or dart system would be even more lethal, as they would be smaller, less noticeable, and let's not forget, have the ability to fly.
Outside of the military, micro air vehicles could have applications in entertainment, security, and logistics. Imagine an array of 5,000 micro air vehicles, each equipped with luminous lights, hovering in the sky and dancing in a complex pattern. Such a display might even eclipse the age-old awe of fireworks. In security, the applications would be similar to those in the military -- surveillance. There could be ethically thorny issues regarding the use of automatic robots being used to kill intruders. The US military has stated that it always plans to keep a human in the loop when it comes to making decisions about killing other human beings.