Smart Weapons Need to Be Smarter

In January, an Iranian gunner, using Russian equipment, fired surface-to-air missiles (SAMs) at a Ukrainian passenger airliner, killing 176 people. When the airliner was shot down near Tehran, tensions were high. Iran had struck an American base in response to the U.S. killing of the Iranian military leader Qassem Soleimani. Nervous Iranian anti-aircraft crews expected retaliation, and the gunner in question likely thought he was shooting down a military target.

The incident marked the fourth time a radar-guided SAM destroyed a civilian airliner by mistake. Such accidents have already killed 842 people, and as SAMs proliferate, further tragedies may be in store. These so-called smart weapons aren’t smart enough. But with some relatively straightforward changes, the fourth accidental shoot-down of a passenger jet could also be the last.

Almost all civilian aircraft have transponders that broadcast a signal showing altitude and speed. Just