What is a Controlled Explosion?

By Aatif Sulleyman on at

Today’s uplifting bit of news comes courtesy of Scotland Yard, which has issued the mother of state-the-obvious guidance for anyone who might happen to find themselves stuck in the middle of a terrorist attack in London. “Run as far away as possible,” said Scotland Yard Assistant Commissioner Mark Rowley to the Evening Standard, not actually being sarcastic at all.

“And when you can’t run any further, hide, and then tell – call the police because we’ve got the people, the resources, the firearms to deal with it. It’s very straightforward.”

Indeed. So while summer’s failed to arrive this year, it’s still worth at least trying to get yourself into some sort of fighting -- or flighting, rather -- shape. You wouldn’t want to be the slowest athlete in THE RACE FOR LIFE now, would you?

All of that got us thinking other cheery thoughts, like would you ever admit to tripping someone up to save yourself? And how effective are human shields?

Rather than those though, we’re going to briefly discuss controlled explosions, and what the term actually means. Suspect packages seem to be found on a weekly basis in the UK now, but how do the experts safely dispose of actual bombs? We’re all familiar with the term, but what does it actually mean?

Non-Technical Nonsense?

We got in touch with Sidney Alford, an authority on all things explosive, to find out more.

“As you have presumably deduced, I have been acquainted with explosions and explosives for many years and thus know quite a lot about them,” he told us. “The expression ‘controlled explosion’ has nevertheless given me food for thought for the past 10 years or so.

“I come across it almost exclusively in non-technical articles written by journalists who reserve the expression for explosions made by the military and navies of friendly countries and, more specifically still, to those people who are attempting to render safe what they know or believe to be a munition – most often a bomb of some sort.”

Goodies and Baddies

Yeah, that sounds right. But how could an explosion ever be ‘controlled’? Does someone with indestructible hands clap them around the bomb as it goes off and absorb all of the impact?

“It has little or nothing to do with the success or failure of the operation,” continued Alford. “Indeed, the only defining controlled feature about it is the time at which the ‘good’ operator chooses to press the button to bring about what might turn out to be a devastating failure, uncontrolled by any reasonable definition.

“Were the bomb disposal operator to arrive at the scene too late to change anything and the terrorist’s bomb detonates, the remarkably successful but evil outcome is not, in a journalist’s sense, a controlled explosion but generates a string of such adjectives as ‘wicked’, ‘evil’ and ‘hateful’ not to be honoured with the description ‘controlled’.

“Thus a controlled explosion is one which generates a bang when a goody presses his own button.”

Not Like the Movies

That makes sense. However, bomb disposal teams surely don’t just fiddle around with the electronics, cut a brightly coloured wire and hope for the best. Do they?

“The processes used by such professional operators usually involve the placing of an explosive charge which is part of their tool kit in contact with, or adjacent to, the object to be disrupted,” said Alford. “They may, alternatively, discharge an explosively propelled missile or substance aimed at the object to be destroyed.

“The sought-after result may be the complete destruction of an explosive target or the infliction of enough damage to render it relatively harmless, possibly preserving potentially valuable forensic evidence in so doing.”

A Warning

As Alford Technologies’ Clive Gale explained, Explosive Ordnance Disposal (EOD) techniques are too varied to be listed individually.

“In general terms, the most common objective is to disrupt the device before it can function as designed,” he told me. “The term ‘controlled explosion’ is one often used to inform/warn the local authorities that EOD action is about to be taken and it will involve a bang. This warns people to stay undercover and also warns them that the bang may be bigger than hoped for.”

The Pigstick

Unlike what we see in the movies, bomb disposal experts will not make contact with a munition unless absolutely necessary. The aim is always to resolve the situation remotely. EOD personnel tend to rely on a remote-controlled vehicle called the Wheelbarrow, which can be loaded with cameras, microphones and sensors designed to identify the nature of an explosive through sight, sound or even smell.

Though specific methods are highly classified -- for obvious reasons -- a method detailed in this piece on The Guardian involves a piece of gear called the Pigstick. It too can be attached to the Wheelbarrow and used to fire high-powered jets of water at a bomb, disrupting the circuitry and disabling it with a low risk of detonation.

"Water would be shot out of a cannon at very high velocity," an unnamed expert told the publication. "It penetrates into the object, splatters everywhere and literally takes it apart. Hopefully the timing devices, the motion sensors and whatever may be in the set-up will not have time to make contact and ignite the explosion."

So there you have it. The term ‘controlled explosion’ is essentially a bit of reassuring-sounding fluff designed to keep folks like us calm in potentially hairy situations. Perfect ammunition for your next boozy pub debate.

Image: Defence Images, John Baucher via Flickr