Electro-optical guided bomb
Among the earliest attempts at precision-guided munitions, an electro-optical guided bomb is under man-in-the-loop control. It contains a television or imaging infrared viewer, aerodynamic control surfaces and a two-way link that allows the operator to steer it into the target.
Early television guidance was used as early as the Second World War, but the technology did not provide either sufficiently informative viewing, or adequate control, for any real degree of precision. The first practical precision versions, such as the GBU-8, were developed during the Vietnam War.
The U.S. AZON was a conventional bomb that had been equipped with aerodynamic control surfaces, and could be steered, by radio from a human operator, left and right in azimuth, hence the name. An improved version, RAZON, could be adjusted in range (i.e., range and azimuth). Guidance and control were totally manual, based on what the weapon operator could see in the television link, and using switches to adjust fins to shift the name — it was not "flown" with a control stick as is an aircraft.
A Vietnam-era weapon, the GBU-8, used television viewing to lock the weapon's seeker onto the target, but the weapons officer had no control over it once it was released. This was much less effective than full man-in-the-loop, and was superseded by laser-guided bombs of the PAVEWAY I series.
Electro-optical guidance has become a niche technology for aircraft bombs. It often has problems with visibiity, such as smoke, rain or haze. The target must have reasonable contrast with its background. In many applications, laser-guided bombs have been more practical, but they do require an observer to keep a laser designator aimed at the target.
An electro-optical weapon can be especially useful when there is no ground or "buddy" target reconnaissance, so the operator can fly it into a target whose position is not well known. The GBU-15 and the powered derivative AGM-130 are useful for attacking bunkers and caves not under observation.
- Greg Goebel, [4.0 World War II Glide Bombs (2)]