On 10 March 1956 a six-engined American bomber descended through a solid deck of cloud over the Mediterranean to meet a tanker. It never arrived.

No wreckage was found. No bodies were found. And neither were the two containers of nuclear weapon material it was carrying.

Seventy years later, nobody knows where Inkspot 59 is.

What the Air Force actually admits

The Pentagon’s own account of the accident is remarkable mainly for how little it contains. The published narrative summary of nuclear weapon accidents describes the sequence in a handful of flat sentences.

That is the whole event. An aircraft entered cloud and did not come out of it, and the United States Air Force has never been able to say anything more definite.

Why a bomber was carrying bomb cores in the first place

This is the part that sounds alarming and is actually the reassuring bit.

In the mid-1950s American nuclear weapons were routinely transported in two pieces. The fissile pit — the core — travelled separately from the rest of the weapon, sealed in its own carrying case. Assembly required both halves and a deliberate act by people authorised to perform it.

So Inkspot 59 was not flying with two bombs. It was flying with two cores and no bombs to put them in, and without the surrounding high-explosive implosion system a pit cannot produce a nuclear yield under any circumstances. The DoD narrative says so explicitly.

What remains on the seabed, if it is on a seabed, is a quantity of weapons-grade material in a corroding container. That is an environmental and proliferation question rather than an explosion risk, and it is one of several such packages the Cold War left scattered around the world’s oceans.

The 1956 disappearance of the B-47 and what is known about where it went.

The aeroplane, and why cloud mattered

The B-47 was a genuinely radical machine: America’s first swept-wing jet bomber, six engines slung under a thin, flexible, highly swept wing, and a crew of just three — pilot, co-pilot who also operated the tail turret by remote control, and an observer who navigated and aimed the bombs.

It was also demanding. The B-47 flew a narrow speed band, its thin wing was sensitive to turbulence and loading, and in the 1950s formation flying inside solid cloud was done on instruments, by radio, with no collision-avoidance beyond discipline and prayer.

A flight of four letting down together through an overcast towards a tanker is precisely the scenario in which a small navigational error becomes a very large one. Nothing has ever confirmed a mid-air collision, but the setting invites the thought.

Where it might be

The search area was never pinned down. Contemporary accounts place the presumed loss somewhere between Port Say, an Algerian coastal village near the Moroccan frontier, and a stretch of sea west of Oran. A French press report at the time claimed an in-flight explosion northeast of Saïdia; no debris was ever produced to support it.

French troops searched the coast. Spanish and British warships searched the water. American aircraft searched everything else. Between them they found nothing at all — no oil slick, no floating debris, no life raft, no carrying case.

That total absence is itself unusual. Aircraft that hit water generally leave something. An aeroplane that leaves nothing has either come down in very deep water in one piece, or come apart somewhere nobody thought to look.

Three men went missing on a routine deployment flight and were never found. The cargo they were carrying is still out there too, and it has been out there for seventy years.

The B-47 Stratojet and the aircraft that went missing with it.

The B-47 and the nuclear accidents of 1956.

Sources: U.S. Department of Defense, Narrative Summaries of Accidents Involving U.S. Nuclear Weapons 1950-1980; Center for Defense Information; Shaun Gregory, The Hidden Cost of Deterrence; Aviation Safety Network; the Broken Arrow Project, University of Southern California; USAF serial number records.