World: The Great Helicopter Mystery

• Share

The news that South Vietnamese officials flashed from I Corps last week was nothing less than astonishing: swarms of North Vietnamese helicopters had been sighted in the Demilitarized Zone, they claimed, and more than a dozen had been brought down by allied fire. Thus began the Great Helicopter Mystery.

Beginning two weeks ago and lasting for several nights, allied counter-mortar radar along the eastern edge of the DMZ, where the zone is bordered by the South China Sea, had indeed showed blips that looked like slow-moving, low-flying aircraft—like helicopters. American artillerymen had also reported sighting a series of strange moving lights near the Ben Hai River, the dividing line between North and South Viet Nam. Artillery and aircraft promptly opened fire on the targets and the blips disappeared.

No visual sightings of helicopters were made, and reconnaissance planes found no wreckage. But at about the same time as the U.S. response, several strange things happened. A U.S. Navy patrol boat was sunk off the DMZ by unidentified fire, the nearby Australian destroyer H.M.S. Hobart was holed in at least 200 places by what turned out to be three U.S. air-to-air Sparrow missiles, and three other vessels, including the cruiser U.S.S. Boston, reported that they had been fired on.

Opinion as to what had happened seesawed. Some officers thought it "highly probable" that a misreading of radar signals—images that looked like slow-moving helicopters but were really friendly vessels patrolling offshore—caused the allies to fire on their own ships. At week's end, while a special board of inquiry tried to fathom the mystery, U.S. officials in Saigon allowed that North Vietnamese helicopters might indeed have been in action in the DMZ. Whether or not they have come that far south, big Russian-built helicopters are now a standard part of North Viet Nam's much-improved weaponry.