LAPD bomb truck fireworks explosion: what went wrong?

There is no storage unit behind the cabin. The only thing behind the cabin is the spherical chamber used for the explosions. The rest of the bed is empty.

That’s clearly not true. It’s not a double cab: in the pictures, the area behind the front cabin is a box storage unit.

Maybe some equipment storage but they aren’t packing explosives in there.

The truck was a Peterbilt, apparently close to a 389 (which is what a 3D model is based on.)


Seems to me that there would have been much less collateral damage if they had just left the hatch open. You have to give an explosion somewhere to go.

Next time, they should just bring a backhoe, have it dig a really deep hole, and set off the explosives inside.

That should work great with an explosive designed to fly way up into the air before exploding.

If the explosive event is small enough, you can contain it, and that’s what these total-containment vessels are designed to do. This is critical for dealing with dirty bombs and/or biohazard bombs. Here’s a tour of a bomb disposal rig in Scranton, PA:

Note also that the hatch is on the side rather than the top, for easy access by disposal technicians; if you leave it open for the detonation, a big blast may propel the vehicle (or just the vessel) forward and/or generate a destructive blast wave (possibly with bomb fragments) directed down the road away from the truck.


I’ve done similar shots, on softer targets, using saline IV bags. And I’ve surgically removed a deadbolt from a locked door using a Bic pen body packed with 2" of C-4. It’s fun to get creative with breaching charges.

I didn’t even scorch that door.

I think that’s what happened. If you look at this picture of the destroyed truck, the chamber (without the flange) is visible hidden below :

Also the lid was discovered a few blocks away.

I think that the hatch was improperly fastened, and the anchors holding the sphere to the truck had rusted / deteriorated. The hatch was blown away and the sphere spun/moved back in the truck.

No, the point of the containment chamber is to absorb the impulse of the explosion and retain the products, such that to observers they just hear a loud dull thud. The impulse of the explosion is absorbed into the thick walls of the chamber. There are larger containment chambers that are made of what is essentially cross-wound wire rope which do permit a controlled escape of the gas products (essentially, a suppressor for explosives) but this was clearly a solid spherical chamber rated for a net explosive weight of some modest amount of of explosive (probably 10 or 15 lbs TNTeq) that was clearly exceeded.

Again, this was in the middle of a residential neighborhood, located in a giant urban sprawl. There is no place to dig a “really deep hole”, and even if authorities decided to dig a hole in the middle of the street it would still put all of the underground infrastructure, e.g. water, sewer, natural gas, at risk. Things don’t just go away when you bury them in the ground despite the common belief that this is so.

That’s certainly possible (although I doubt it was rust; Los Angeles is a desert city and unless the truck were parked down on the beach it is rare to see vehicles really rusted out); I didn’t realize the chamber was still mostly intact. As @Tripler notes above, you need to inspect and maintain all critical tools. But it is also still plausible that the technicians just underestimated the yield of the devices they put into the chamber. Either way, you definitely want to double and triple check your work when dealing with explosives and energetics because you can’t just reset and recycle.


That doesn’t always work well either. Five deaths in Hawaii.

Watched through your linked video, half way through. Saw them soaking fireworks / blackpowder in diesel not water.

If you’d watched it to the end you’d find, at least at the time the video was made (2013) there is no set procedure for safely destroying seized fireworks. It wasn’t the diesel oil, per se, that caused the explosion; it was dragging everything in out of the rain. Water would not have helped.

I don’t suppoae it was an ACME bomb disposal unit? Were there any coyotes involved?.

Some clarity - overloaded.Chief: Bomb squad caused Los Angeles fireworks explosion
“…The bomb technicians — without using a scale, as is allowed by Los Angeles police procedures to avoid additional handling of the unstable devices — estimated the weight of the homemade explosives and a counter-charge to be about 16.5 pounds (7.5 kilograms) in a standard flash powder measurement. That measurement is not the same as an item’s physical weight and is instead calculated as a TNT equivalent because explosives have different concentrations and therefore have varying “explosive weights.”

They arrived at 16.5 pounds by estimating that the smaller explosives — there were 280 of them — each weighed about a half an ounce (14 grams) in that standard measurement. The bomb technicians estimated that the 44 larger explosives — which were about the size of a soda can with a fuse — had about 1.5 ounces (42.5 grams) worth of flash powder.

Federal authorities who weighed the remains after the blast calculated that the weight was actually more than 42 pounds (19 kilograms) in the standard measurement. The smaller explosives were actually 1.37 ounces (38.9 grams) and the larger ones were about 5 ounces (142 grams).“The detonation chamber’s maximum capacity is 15 pounds (6.8 kilograms) for multiple uses or 25 pounds (11 kilograms) for a single use, Moore said. The LAPD has not publicly identified the manufacturer of the detonation…”

That’s a big underestimate.

They put in twice the recommended amount and it went to pieces? In Medicine or Engineering that’s a small margin of error.

Looks to me like it exceeded specifications. It was rated at 11 kg for a single use, and they achieved a single use with a whopping 19 kg :slight_smile: .

Will a detonator (for HEX) also ‘set off’ packed powder charges as described here? Assume no other HEX materiel. A cache of fireworks.

That’s still better than Oregon’s exploding whale.

I believe the increase is a square of the explosives weight. That’s what got Hal Needham in trouble when he was developing the car flipping cannon.

“We built a cannon 16 inches in diameter with inch-and-a-half-thick walls—because I knew what was going to happen inside that cannon—and welded it to the back floorboard behind the driver’s seat with the muzzle pointed toward the ground,” Needham explained to Ben Stewart of Popular Mechanics. That cannon was loaded with a three-foot section of telephone pole and a black-powder charge. “The idea was to throw the car in a broadside skid and hit that cannon.”

But after a static test had proven the formula inadequate for the task, the crew upped the powder charge—by far too much—for a rolling test with Needham driving. When Needham triggered the cannon at 55 mph, he soon found himself flying upside down at an altitude of 30 feet. He broke six ribs, his back, and punctured a lung. “The lesson I learned on this one,” he told Stewart, is that “powder squares itself in power.”