Bomb shuts down London City Airport

Originally published at:


we simply don’t know where they are

I see a business opportunity.


London City Airport:
Opened 1987; 31 years ago

500kg bomb:
Dropped ~1941; 77 years ago

Those airport squatters will have to move.


The Germans dropped it, make them pick it up.


But then Britain will have to collect all the unexploded bombs they dropped on Germany.


Abundance of caution and all that – I get it. But in practical terms, what are the odds that one of these things actually does explode, 70-some-odd years later?

And, if I may be permitted a follow-up question, at what age (100 years? 200? 1000?) will this stuff become (reasonably) benign? Let’s define “benign” as the point where, upon finding this, the cops just say “yeah, that’s an old one, you’re gonna have to dig it out yourself, don’t worry, it’s not very likely to go off.”


Obviously there should be a deposit on those things, especially landmines, to encourage recycling.


Yeah, I have a similar question in mind: Does this stuff ever just spontaneously(/during accidental manipulation) go off?

As in: Breaking news! There is now a huge crater where a city block used to be and we do not know why, yet.


In France, the Departement du Deminage employs over a hundred people full time to collect and detonate unexploded ordinance from the two world wars. See Donovan Webster’s Aftermath: The Remnants of War. Considering the risks and the low rate of return, not to mention the worker’s compensation costs (20% of the demineurs get injured or killed every year), I doubt any private entity would be interested in taking on the job.

eta: it is estimated that it will take 700 years to completely clear France of unexploded WWI ordinance at the current rate of clearance. see also:


I’m not an expert but I’ve read a number of articles on this subject over the years. Old munitions are rather unpredictable. Some become inert over time but many do not. Bombs with delay action fuses are particularly dangerous when disturbed because the motion activates the fuse. So, these bomb removal experts treat each and every removal as if it has the potential to explode.


Underwater Cow, a sequel to Unexploded Cow?


I don´t know how this is news. There are countless tons of unexploded british and american bombs all over Germany. Just last september I and over 60,000 other citicens of Frankfurt had to evacuate because they found a 1.8 ton british blockbuster at a construction site just a few blocks from my flat. A blockbuster is called that way because the explosion is strong enough to leven a whole street block. The idea was that a blockbuster explodes a few hundred meters above the city so that the blast wave can destroy roofs and windows so that following bombers carrieing incendiary bombs have a easier job sending the whole area ablaze. Lovely.


Reminds me of this classic British show:


There goes the myth of German engineering…

Are they sure it was a bomb? Did they look inside?


It happens sometimes. There were fatal accidents with WWII bombs near the town where my parents live (in north-eastern Poland). Some accidents were caused by people trying to disassemble the bomb by themselves (it was a popular past time hobby 20 years ago).
Finding unexploded bombs is still so frequent there, that it doesn’t even make the news.


Not an expert, but AFAIK, if the metal casing remains semi intact, the explosives inside remain potentially dangerous. If the metal casing corrodes completely away, then eventually the explosives inside would degrade and decompose. The metal casing tends to be pretty robust, though, so it takes a very long time to rust through enough to let water and bacteria get at the insides.

I say potentially dangerous because high explosives don’t go off by themselves, you need a detonator. By definition, these unexploded shells have something wrong with their detonators, otherwise they would have blown up as intended when fired/dropped. That something wrong could be major (in which case it’s not going to go boom no matter what) or minor (in which case rough handling or a static spark could be enough to make it go boom). Source: Aftermath: The Remnants of War by Donovan Webster.

Knowing how touchy the detonator is, is the tricky part. The real problem is that defective detonators are unpredictable. Webster relates the story of a blacksmith shoemaker who used an unexploded shell as an anvil for years and years in perfect safety, and then one day, boom. To be safe, you have to treat each and every bomb like it might go off.

eta: I misremembered the shoemaker anecdote.


A few years ago, when I lived in Munich I learned quite a bit about time-delayed fusing bombs, as one was found just below a popular bar which was being razed to make way for a new building. The idea of those bombs was that it would explode one or several hours after the bomb raid, i.e., when rescue work was going on, like clearing cellar entrances from rubble etc., such that it would kill the rescue teams…

We are really quite lucky to live in a time and place where these kind of contraptions are not being deployed on us. Others are not that lucky.


15 percent or more of shells fired by all sides in WW1 failed to detonate.

Partly due to badly designed fuzes. For example, Britain did not have a high explosive artillery shell when the war started, (British military doctrine adopted in the Boer war was to rely on shrapnel shells only, this did not work well against barb wire or trenches). So for the first couple years of the war they relied on a HE shell designed in less than 10 days.

Partly due to most shells being produced by companies and workers with no experience in munitions. Something like one billion artillery shells were fired in the Great War, far more than the prewar munitions industry could possibly produce. Quality control suffered greatly in the rush to keep artillery divisions supplied with ammunition.



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