In 1945, the armed forces needed 100 B-19s and an average of 650 bombs to destroy a single ground target. Today, they can do it with one plane and one or two bombs.
Yet after more than 50 years of development, “precision bombing” is still subject to mistakes — electronic, mechanical, human — that can exact a deadly toll and can have far-reaching political consequences.
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The imperfection of the system was painfully on display again Tuesday, as the Pentagon disclosed that several bombs had gone astray over the weekend in its military campaign in Afghanistan.
Experts say that despite the sophistication of modern weaponry, such accidents can happen for several reasons.
A bomb can fall off its aircraft rack prematurely. A loose tail fin can send it veering miles off course. The morning dew can briefly blind its laser-guidance system. Or a tired, stressed air crew member might punch the wrong numbers into a satellite-guidance system.
After years of effort and billions of dollars in investment, today’s bombing system “is a lot better, a lot safer” than in previous conflicts, said retired Adm. Stephen Baker, a former Navy pilot and weapons tester.
But, he added, “It’s not perfect.”
The U.S. effort to develop precision-bombing techniques became visible with the “smart bombs” of the Vietnam War era, and came fully into its own in the 1999 war against Yugoslavia.
In the Balkan war, only 20 of the 23,000 munitions used went awry and inflicted “collateral damage,” according to the Pentagon’s tally. Yet those incidents brought worldwide attention — especially when a bomb fell on the Chinese Embassy in Belgrade, killing three people — and repeatedly threatened to sunder the fragile European coalition that backed the NATO war effort. The bombing of the embassy resulted from an erroneous U.S. map, an example of how faulty intelligence can lead to such mistakes.
When the war was over, the Pentagon again intensified its effort to make its bombing techniques more precise.
Increasingly, the mixture of munitions used by U.S. forces has centered on bombs that use precise laser-guidance systems and those that rely on satellite-guidance gear. The satellite-guided bombs can be used more effectively than others in bad weather.
Laser-guided bombs are the most precise because they follow a thin beam to a point on the ground. Yet they can be thrown off by rain, clouds or even heavy fog or dust.
Such bombs often are used by tactical fighter jets that aim a laser beam on a target as the aircraft fly at 500 m.p.h. at low or medium altitude.
The systems also can be knocked off if the aircraft hits turbulence.
On other occasions, smoke from the explosion of one bomb will drift in front of a second target, interrupting the laser beam and throwing off the bomb, said Baker, now an analyst with the Center for Defense Information think tank in Washington.
The military has spent billions of dollars over the years trying to automate target systems in ways that would make them less subject to glitches.
In the Vietnam War, targeting information was passed among controllers and pilots and headquarters in a system that was labor intensive and subject to occasional errors.
Now the process has been computerized. Yet humans must perform several tasks.
They can make mistakes, as occurred in mid-October when a U.S. service member apparently transposed two digits in targeting data. The mistake sent a 2,000-pound bomb crashing into a row of homes in Kabul, killing at least four people.
Errors also can occur during the complicated process of converting maps into numerical targeting data.