DMZ 'enemy helicopters' and HMAS Hobart
In June 1968 US forces near Vietnam's Demilitarised Zone reported mysterious low, slow lights taken for North Vietnamese helicopters; in the confusion US jets attacked their own ships.
1968 CE · 17.15, 107.25 · status: disputed
The account
On the night of 16–17 June 1968, US Air Force jets responding to such contacts fired on the Australian destroyer HMAS Hobart, killing two sailors, and damaged USS Boston; a US swift boat was also sunk. The 'helicopter' sightings were never fully resolved and are sometimes cited in UFO literature.
The sceptical view
Investigations concluded the attacks were friendly fire, and many contacts were probably radar artefacts, misidentified aircraft or flares. The deaths were a real tragedy, not a mystery of origin.
The researched reading
A deadly chain of misidentification under combat pressure, with radar unable to separate ships from helicopters. The UFO reading adds little; a few unexplained lights remain in anecdotal accounts.
| Explanation | Weight | Why |
|---|---|---|
| Something known, misidentified | 50% | The US Navy inquiry found the "helicopters" attacked that night were friendly ships and boats: Seventh Air Force F-4 crews could not tell the radar returns of small surface vessels from slow, low aircraft, and fired on PCF-19, Point Dume, HMAS Hobart and USS Boston. Many earlier "helicopter" lights were flares, aircraft or misread radar. |
| Secret human technology | 13% | Some contacts may really have been North Vietnamese helicopters or other aircraft operating at night; some writers also suggest secret allied flights. |
| A known natural phenomenon | 10% | Anomalous propagation over the warm Gulf of Tonkin produces false or displaced radar targets, and coastal temperature inversions in summer are common. |
| Perception, memory or mind | 10% | Combat stress and expectation of an air threat turned ambiguous blips and lights into "enemy helicopters", and the pressure to act fed the friendly-fire chain. |
| Genuinely anomalous | 7% | A residue of low, slow lights seen from the ground was never fully resolved, but the instrument data that exist are well explained by friendly-fire misidentification. |
| Undetermined | 5% | The share a generic explanation had beyond what has been shown for this case: it fits many cases like this one, but has not been demonstrated for this one. |
| A poorly understood natural phenomenon | 4% | Some floating lights reported along the Ben Hai river are not individually explained; poorly understood luminous phenomena are a small possibility. |
| A hoax or fabrication | 1% | The deaths and damage are fully documented; there is no sign of invention, only later UFO framing. |
Official position: US and Australian inquiries concluded the attacks were friendly fire by USAF aircraft mistaking surface vessels for helicopters.