How many nuclear weapons have been lost- and not located or recovered-- from aircraft in crashes or other mishaps?


Short answer, quite a lot but total unclear (and not just for secrecy reasons) - most are due to the US practice of keeping a force of nuclear bombers airborne continuously and/or routinely going on alert to test readyness, at a time when aviation technology was advancing ahead of reliability (see B-36 'six turning four burning'').

General incident lists here and here. It is challenging to get a clear count of 'lost and not located' for several reasons. In the early era of nuclear equipped bombers it was common for the casing, electronics and conventional explosive 'bomb' to be carried on separate aircraft from the plutonium cores/capsules, or for cores to be in a separate stowage during normal operation. This means that there were several 'nuclear bombs' jettisoned or involved in crashes that were just very very expensive conventional bombs during the incident - many were not 'recovered' because they were mostly high explosive and either deliberately detonated or caught fire. Some of these bombs contained Uranium tampers (Uranium used for density rather than for atomic properties) further complicating the definition of 'lost', finally there are weapons that burned and contaminated the soil (so weapon is lost, material is not).

1956 - B-47 lost in transit to Morocco - carrying two cores but no bombs

1957 - Air to Air missile test - questionable since it was an intended detonation but notable for photo of five people at ground zero

1958 - weapon jettisoned after mid air collision - unclear if core fitted

1958 - B-47 in Morocco burns on ground, contaminated soil returned to US.

1958 - B-47 catches fire on ground in UK while bomb loaded - radioactivity detected by UK teams but US claim no capsule fitted.

1960 - BOMARC missile destroyed by fire - technically not 'lost' since the contaminated area is known and some material recovered during cleanup

1961 - B-52 crash, parts of weapons recovered from marshland but not all.

1965- Mk43 equipped A-4 rolls off carrier deck and not recovered

1966 - B-52 crashes in Spain, two weapons exploded/burned on land, two sank in water. Intact weapons recovered and soil returned to US.

1968 - B-52 crashes and burns in Greenland - soil returned to US for re-processing so not technically 'lost'.

Notably absent from this list is everybody other than the US. UK and France had far fewer weapons, so tended to keep them safe on the ground/prioritize missile delivery though UK did do 'alert' operation so not impossible that a still unreported event happened with the V-bombers. Russia is a more opaque question, but placing more priority on ICBMs over bombers and desire for central control means that far fewer aircraft flew with complete weapons and those that did would have tended to be over land so is statistically possible no USSR/Russian aircraft crashed/were lost while nuclear equipped in a way that prevented recovery. It is unclear if China ever widely deployed nuclear bombs and also tends to operate over land.

If planing to go looking for one, the half life of Plutonium used in weapons is 14 years, so all the weapons in this list (and unknown ones of this era) would no longer be capable of a full nuclear detonation if recovered today. Recovery would still be highly dangerous due toxic materials and unstable explosives.


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