Genuine aviation mysteries are rarer than popular accounts suggest. Most disappearances that get called unexplained turn out, on examination, to have a defensible explanation that is simply less interesting than the alternatives. These ten are the ones where the question is still genuinely open.
1. Malaysia Airlines MH370 (2014)
A Boeing 777 with 239 aboard turned back, flew for nearly seven hours, and has never been located. Satellite handshakes and recovered debris constrain where it went. Nothing establishes why.
2. Amelia Earhart (1937)
Vanished searching for a two-kilometre island in the Pacific. Crash-and-sink fits the evidence best, but no wreckage has ever been identified, and two competing theories persist on inconclusive material.
3. D.B. Cooper (1971)
The only unidentified hijacker in American aviation history. He jumped from a 727 over Washington State with $200,000 and was never found. A partial recovery of the ransom in 1980 explains less than it complicates.
4. Flying Tiger Line 739 (1962)
A Super Constellation carrying 107 people disappeared over the western Pacific. A tanker crew reported a bright light and falling objects. No wreckage was found in water among the deepest on Earth.
5. Star Tiger and Star Ariel (1948, 1949)
Two Avro Tudors from the same small airline vanished in the same region within twelve months, without distress calls or debris. Two losses of one troubled type suggests a technical cause nobody could prove.
6. Varig 967 (1979)
A Boeing 707 freighter disappeared thirty minutes out of Tokyo with six crew and 153 paintings aboard. One of the very few large jets ever lost without trace.
7. Frederick Valentich (1978)
A young pilot described an object above his Cessna to a controller, then disappeared over Bass Strait. The transcript is official and the closing sound has never been explained. Spatial disorientation covers much of it, not all.
8. Glenn Miller (1944)
A single-engine transport lost over the Channel in icing conditions. The likeliest answer is mundane, but competing accounts persist and no wreckage has been found.
9. Flight 19 (1945)
Five Navy Avengers and a rescue flying boat lost off Florida. The radio transcripts make the navigational error reasonably clear; what was never resolved is where they went into the water.
10. BOAC Flight 781 crew questions and the early Comet losses
The technical cause was solved brilliantly. What remains debated is institutional: how a fleet was returned to service after the first break-up on hypotheses that turned out to be wrong.
What they have in common
Almost all of them involve deep water, and almost all of them predate the technology that would have resolved them. An aircraft lost over land is usually found. An aircraft lost over an ocean four kilometres deep, before the era of autonomous underwater search, generally is not.
The other common thread is the absence of a recorder. Every case here either predates flight recorders or lost them with the aircraft. The reason modern accidents are almost always explained is not that modern aircraft fail more comprehensibly. It is that they carry two orange boxes that survive.