What was the 'People Sniffer'?

Short answer

It was the field name for a series of "personnel detectors" used by the US Army in the Vietnam War to locate enemy soldiers in hidden positions. They detected chemical compounds emitted only by humans, such as those in urine and sweat. They were developed by General Electric.

Published: November 1, 2026 · Updated: November 1, 2026 · Edited by Above Ten Thousand · Editorial policy

Huey UH-1 helicopter in Greenup, KY, USJud McCranie (CC BY SA), vía commons

A personnel detector

"People sniffer" was the field name for a series of "personnel detectors" fielded by the United States Army during the Vietnam War. They were personnel detectors used by the US armed forces in that conflict. Their purpose was to detect enemy soldiers in concealed positions, common in the jungle combat conditions of Vietnam. The technology was developed by General Electric for the Army Chemical Corps.

How it sniffed

The people sniffers' detection method relied on chemical compounds emitted only by human beings, such as those found in urine and sweat. The XM-2 consisted of a backpack-mounted sensor with an air intake tube at the end of a rifle.

From backpack to helicopter

The XM-2 proved problematic, because it often detected the soldier carrying it instead of the enemy. The XM-3, an airborne personnel detector, was the second version of the people sniffers and was mounted on a helicopter. That airborne version became standard equipment and was used almost daily on LOH-6, OH-58 and UH-1 helicopters. People sniffers, in general, were excessively sensitive and often detected civilians or animals excreting bodily waste. The detectors responded randomly to ammonia indicators, which made them a highly subjective instrument.