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I just heard of something scary from a local law enforcement officer, but I have doubts about it being true. He stated that a new crime method has been seen where one perpetrator starts to "dance" near the drive'rs window when a car is at a red light, capturing the attention of the driver. The second criminal strikes the front bumper of the car with a 5-lb sledge hammer, activating the air bag. The first criminal then smashes the driver's window and drags the confused driver out of the car for whatever mayhem they have in mind for the driver. My question is: would a 5-lb or other hand held hammer striking the bumper really be enough force to activate the airbag?
 

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Wow, just wow.

There has to be certain speed perimeters before airbags activate. Even then, it has to be a pretty significant impact to set off an airbag sensor. Finally, if the speed perimeters were met, you would have to be very lucky to hit the front with a hammer just in the right spot to hit an airbag sensor.

That Officer must not worth traffic crashes that much. He must also be one that believes a slim jim could set off a side airbag. I also suspect he is "that guy" on the department that everyone just rolls their eyes at.
 

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That sounds nutty. I would think you would have to have something more than a 5 lb sledge perfectly aimed to set off the airbags. They are specifically designed not to go off at low speed when you have a fender bender. Thats 3k-5k pound of car hitting something else that may or may not be moving. I just find it hard to believe.
 

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The airbag module calculates a lot of vehicle data before popping an airbag. A sledge hit on the front bumper of a stopped car won't do it.
OTOH...
 

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The answer is - it depends. And it's highly unlikely.

The airbag sensor is typically located on a structural member behind the front bumper and grill. It is designed to activate the airbag if it detects sudden deceleration. Usually this occurs if the frontal impact is strong enough to collapse the bumper and result in direct contact to the vehicle's structural frame. The airbag sensor can be triggered fairly easily if hit DIRECTLY with a hammer IN THE RIGHT SPOT AND DIRECTION.

It is very unlikely that a hammer blow to the bumper, grill or hood will produce enough acceleration to the sensor itself to activate the airbag. The perpetrator would need to know exactly where the airbag sensor is located in your particular vehicle, and hit your vehicle hard enough to contact the sensor.
 

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The answer is - it depends. And it's highly unlikely.

The airbag sensor is typically located on a structural member behind the front bumper and grill. It is designed to activate the airbag if it detects sudden deceleration. Usually this occurs if the frontal impact is strong enough to collapse the bumper and result in direct contact to the vehicle's structural frame. The airbag sensor can be triggered fairly easily if hit DIRECTLY with a hammer IN THE RIGHT SPOT AND DIRECTION.

It is very unlikely that a hammer blow to the bumper, grill or hood will produce enough acceleration to the sensor itself to activate the airbag. The perpetrator would need to know exactly where the airbag sensor is located in your particular vehicle, and hit your vehicle hard enough to contact the sensor.
You still have the problem of the car being below the minimum speed. A quick google search shows the car has to be going about 14 mph before the airbags can deploy (if there are the right circumstances).
 

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The old woman in the video is staged, I don't think that is for real, nor do I think such a blow would cause the airbags to deploy. If they did deploy that easily, you would be seeing it happening on a daily basis in a large city. Come to think of it, I have never seen an airbag deploy anywhere, and I have seen new cars bump into things, including my own cars!
 

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The front airbag sub-sensors, which are essentially electronic strain sensors, are sensitive to sudden stopping (deceleration) G-force. (They do not have to be directly involved in the collapse of frontal material.) This requires the sensor to be moving in the forward direction to begin with.

Hitting the bumper of a stopped car will cause the bumper cover to indent, and perhaps crush the foam absorber in behind, but the car's main frame rail that the sensor is mounted on will likely remain still. Even if the brakes are off at the time and the car could roll, a sledge hammer strike to the bumper isn't going to cause the car to suddenly lurch backwards at a speed that would develop significant G-force. Moreover, if it did, it would be in the wrong direction!

And, to top it off, the control module requires a second input to verify the situation before deploying the airbag; in this case, there's a separate g-force sensor inside the car.
 

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The old lady video is most definitely staged, and it irritates me every time some moron sends it to me in an email because they believe its real.

Theoretically you could set off an airbag with an impact whilst not moving, but its very unlikely. I believe for it to happen the system has to see the engine running, and may involve other factors that indicate to the SRS module that the vehicle is occupied. You could be hit whilst stationary by a moving vehicle, but you wouldn't want a costly airbag deployment if someone hit your parked car. Thus, the design rationale. However, if a 5lb sledge applied fairly randomly could set off an airbag, lots of people parking their car and hitting a parking curb would be setting off airbags.
 

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LOL - your friend is full of BS!

Air bag systems use combined data to trigger the bags and which bags. Not to mention chances are you have a higher chance of getting hit by a Bus driving to work than some team of wackjobs dancing and toting sledgehammers just to get their rocks off during commute hour.
 

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RE-POST: URBAN LEGEND. Though I do like the part about dancing. Maybe if all those guys begging at city stoplights danced they'd get more money. lol (or tasteless?)
 

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You still have the problem of the car being below the minimum speed. A quick google search shows the car has to be going about 14 mph before the airbags can deploy (if there are the right circumstances).
Exact speed for airbag deployment varies depending on the collision physics involved. The airbag engineering data is proprietary and is a closely guarded secret by auto makers.
A stopped vehicle can have a deployment if it is struck by another vehicle with sufficient energy.
 

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From page 1-55 of the 2013 Outback owners manual under situations when the front airbags may deploy:
A head-on collision against a thick concrete wall at a vehicle speed of 12 to 19 mph (20 to 30 km/h) or higher activates only the driver’s SRS frontal airbag or both driver’s and front passenger’s SRS frontal airbags.
On page 1-57, you will see examples of when the airbag will NOT deploy. One of those examples is a telephone or sign pole.

So, the Outback needs to be going at least 12-19 mph and hit something like a brick wall before they airbags will deploy. Also, if the airbags won't deploy from hitting a light pole, a hit on the bumper from a hammer probably won't do it either.

Myth busted.

Edited to add link to owners manual: http://techinfo.subaru.com/proxy/68511/pdf/ownerManual/068511_2013_Legacy/A2490BE-BSTISJuly10_8.pdf
 

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My step daughter was driving a friend's late 90s Honda Accord (when she didn't yet have her license) and ran it up on a curb in a parking lot. She had gone wide in a turn being a dork and hit the sidewalk.

Both front bags deployed and there was no visible damage to the front end of the car and certainly no caved in bumper.

This is first hand observation and not "I know a guy".
 

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My step daughter was driving a friend's late 90s Honda Accord (when she didn't yet have her license) and ran it up on a curb in a parking lot. She had gone wide in a turn being a dork and hit the sidewalk.

Both front bags deployed and there was no visible damage to the front end of the car and certainly no caved in bumper.

This is first hand observation and not "I know a guy".
I imagine there was some sort of undercarriage damage if she hit the curb that hard.

From page 1-56 in the above link I posted:
...SRS frontal airbags may be activated when the vehicle sustains a hard impact in the undercarriage area from the road surface (such as when the vehicle plunges into a deep ditch, is severely impacted or knocked hard against an obstacle on the road such as a curb).
A sudden hit to a cross member or front axle from a cement curb would jolt the airbag sensor pretty good but front car bumpers are nothing more then a soft plastic shell which usually has a styrofoam-like core for cushioning. A hammer blow to the bumper would just damage the plastic and foam. The rest of the car probably wouldn't even feel anything (unlike a hit from a curb).
 

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Some of these issues could be due to defective parts, also. VW had some issues with side curtain airbags going off if you went over a pothole. No damage to the car... Just wonky sensors.

I doubt every carmaker handles it the same way, but I understand that they have dropped the minimum speed for airbags so that they will go off even if you are stationary. This helps in cases where you are sitting still and another car hits you... Or if you are in a frontal collision in an intersection, then another car t-bones you.

Still, the OP's story sounds like urban legend. Kind of like all the AIDS tainted needles in change slots, or razor blades in Halloween apples.
 

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Still, the OP's story sounds like urban legend. Kind of like all the AIDS tainted needles in change slots, or razor blades in Halloween apples.
Or this one snopes.com: Gang Initiation I've had half a dozen well meaning friends forward this email to me. If you are suspicious about a dodgy story go to www.snopes.com I've submitted this "airbag" story there. Let's see what they say.
 

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My step daughter was driving a friend's late 90s Honda Accord (when she didn't yet have her license) and ran it up on a curb in a parking lot. She had gone wide in a turn being a dork and hit the sidewalk.

Both front bags deployed and there was no visible damage to the front end of the car and certainly no caved in bumper.

This is first hand observation and not "I know a guy".
Bag sensors detect inertia for deployment. Actual physical contact with the front bumper isn't necessary to pop them.
 
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