Introduction: Why are airbags needed and how do they save lives?

Airbags (airbag) is one of the key passive safety systems in modern cars, which reduces the risk of injury in road accidents 30–50% depending on the type of collision. Despite its apparent simplicity (the bag unfolds and that’s it), this is a complex mechanism where every millisecond matters. In this article, we will look at how an airbag works from the inside: from triggering sensors to inflating the bag within 0.03–0.05 seconds - faster than you can blink.

Have you ever wondered why the airbags don't deploy with every impact? Or why in some accidents they do not open at all? The answer lies in control unit (ECU) algorithms that analyze not only the force of the impact, but also its direction, the speed of body deformation and even the position of passengers. We will show real videos of deployment, explain how to check the system yourself, and reveal myths - for example, that airbags can deploy under heavy braking (spoiler: no).

Airbag design: what does the system consist of?

System airbag is not just a bag hidden in the steering wheel or panel. It includes several key components, each of which has its own role:

  • 🔧 Shock sensors — determine the force and direction of the collision. In modern cars there can be up to 10–12 pieces (front, side, in doors, under seats).
  • 📶 Control unit (ECU) — the “brain” of the system, which makes a decision about operation in a split second. Analyzes data from sensors and activates squibs.
  • 💥 Squibs (gas generators) - explosive devices that release gas when triggered (usually nitrogen or argon) to inflate the pillow.
  • 🛡️ Pillow bag — made of nylon with silicone coating so as not to tear when opened. In some models (for example, Toyota Camry 2020+) multi-layer fabric is used.
  • 🔄 Diagnostic system — constantly checks the integrity of the circuits. If it detects an error (for example, a broken wire), the indicator lights up on the instrument panel SRS/Airbag.

Fun Fact: The first airbags (1970s-1980s) used compressed gas in cylinders, but modern systems operate on the basis pyrotechnic reaction. For example, in pillows Bosch or Autoliv when triggered, the tablet ignites sodium azide (NaN₃), which instantly decomposes into nitrogen and sodium. The latter is neutralized with special additives so that there is no risk of fire.

📊 How often do you check the operation of the airbags in your car?
Never
Once a year
Only when the SRS light is on
After every accident

How an Airbag Deploys: Step-by-Step Process

The entire actuation cycle takes less than 100 milliseconds. Let's break it down step by step:

  1. Impact detection (0–2 ms): sensors detect sudden deceleration (for example, in a head-on collision at speed 30–40 km/h). Critical value - deceleration 3–5g (depending on the car model).
  2. Data Analysis (2–10 ms): block ECU checks whether there is a false alarm (for example, from hitting a curb). In modern machines (for example, Volvo XC90) even the position of the seats and seat belts is taken into account.
  3. Activating the squib (10–15 ms): an electrical impulse is sent to the gas generator. The temperature inside reaches 300–600°C, but the bag does not burn thanks to the heat-resistant coating.
  4. Inflating the pillow (15–30 ms): gas fills the bag at a speed 200–300 km/h. At this moment a characteristic clap is heard.
  5. deflating (30–100 ms): gas is released through holes in the bag so as not to block the view or suffocate the passenger.

Important: pillows do not operate when tipped over (there are curtain airbags for this) and do not always open during a side impact - it all depends on the crumple zone. For example, in Ford Focus 3 The side airbags only deploy if the impact hits the door area at a speed higher than 25 km/h.

Why don't airbags deploy in a minor accident?

Even with visible deformation of the bumper, the system may not be activated if:

- The impact speed was below the threshold (typically < 20–25 km/h for front airbags).

- The impact fell in a “soft” zone (for example, a plastic bumper absorbed the energy).

- Sensors detected non-critical deceleration (for example, when hitting a snowdrift).

Types of airbags: what they are and where they are installed

Depending on the car model, the number of airbags may vary from 2–4 (budget cars) up to 10–12 (premium segment). Let's look at the main types:

Pillow type Installation location Purpose Examples of cars with such a pillow
Front (driver's) Steering wheel Head and chest protection in case of frontal impact All cars from the 1990s
Front (passenger) Glove box (dashboard) Front passenger protection Lada Vesta, Hyundai Solaris
Lateral Front seat backs Side impact torso protection Kia Rio, Skoda Octavia
Curtain airbag Ceiling (above doors) Head protection in the event of a side impact or rollover Toyota RAV4, Mazda CX-5
Knee Under the steering wheel or dashboard Prevents leg injuries Mercedes E-Class, BMW 5 Series

In the latest models (for example, Tesla Model 3 or Volvo XC60) appear center cushions between the front seats - they prevent passengers from colliding with each other in a side impact. And in Mercedes S-Class pillows are used multi-stage operation: first inflate by 70%, and if the blow is stronger - up to 100%.

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If your car has side airbags in the rear seats (for example, Audi Q7), do not hang covers or blankets on them - this may interfere with operation.

When airbags will NOT deploy: common reasons

Many drivers mistakenly think that airbags deploy in any accident. In fact, there are several scenarios when the system remains inactive:

  • 🚗 Speed too low: Most systems are configured to respond to an impact at a speed from 20–25 km/h. At lower speeds, the risk of injury is lower than from the airbag itself.
  • 🔋 Disabled system: if the dashboard lights up SRS, the airbags may not deploy. Causes: broken wiring, faulty sensor or reset fuse.
  • 🛠️ Improper repair: after an accident, some “masters” simply replace the airbag without resetting the error ECU. As a result, the system thinks that the airbag has already deployed and blocks reactivation.
  • 👶 Deactivated passenger airbag: in many cars (for example, Renault Duster) it can be turned off with the key if a child is riding in the front seat.
  • 💺 Unfastened seat belt: on some models (eg Ford Mustang) airbags deploy with less force if the passenger is not wearing a seatbelt to avoid causing additional injury.
⚠️ Attention: If you bought a used car after an accident, be sure to check the history of the airbags! Fraudsters often install fakes (for example, inflatable bags without squibs) or simply “reset” the light bulb SRSwithout restoring the system. You can check this with a diagnostic scanner (for example, Launch X431) or by marks on the steering wheel/dashboard - after operation, characteristic marks remain.

How to check airbags yourself

System diagnostics airbag can be divided into visual inspection and electronics check. Let's start with the first one:

- Condition of the steering wheel and dashboard: are there any cracks or signs of repair (a sign of airbag deployment).

- Light bulb SRS/Airbag on the dashboard: should go out 3-5 seconds after starting the engine.

- Cushion mountings: there should be no play in the front seats (under the trim).

- Fuses: Locate the fuse in the block SRS (usually 10–15A) and check its integrity.

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For in-depth diagnostics you will need OBD-II scanner (for example, ELM327 or professional Autel MaxiCOM). Connect it to the connector (usually under the steering wheel) and follow these steps:

  1. Select the section in the scanner menu SRS/Airbag.
  2. Count your mistakes. Type codes B1000 or B1015 indicate a sensor malfunction, B1869 - for problems with the passenger airbag.
  3. If there are no errors, but the light is on, check the wiring (wires under the seats often fray).
  4. After troubleshooting be sure to clear errors through the scanner!

Important: Do not try to check the pillows "manually" (for example, by applying voltage to the squib). This may lead to uncontrolled operation and serious injury. Even specialists in car service centers use special stands and protection.

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If after an accident the airbags do not work, but the light SRS does not light up, this does not always mean that the system is working properly. Perhaps the sensors “did not see” the impact due to damage to the body. In this case, a complete diagnosis at a service station is required.

Airbag deployment video: what you can see

There are a lot of crash test videos on YouTube where you can clearly see how the airbags work. Please note the following points:

  • 🎥 Opening speed: in slow motion you can see how the bag is inflated by 0.03 seconds (for example, in tests Euro NCAP).
  • 💨 Cloud of dust: when triggered, talc or starch is released (used to lubricate the bag), which many people mistake for smoke.
  • 🔊 Sound: The pop when triggered is not an explosion, but a sudden release of gas. In the cabin the noise level reaches 140–160 dB (like a pistol shot).
  • 🚗 Mannequin behavior: in a properly working system, the passenger’s head does not hit the steering wheel or glass, but “sinks” into the pillow.

Examples of useful videos to study:

- "Slow Motion Airbag Deployment" (channel SmarterEveryDay) - shows details of the process at 10,000 fps.

- "Euro NCAP Crash Tests" - comparison of the performance of airbags in different cars (for example, Skoda Kodiaq vs Dacia Sandero).

- "Airbag Fraud Exposure" (channel ChrisFix) - how scammers fake deployed airbags.

⚠️ Attention: If you are looking for videos of real accidents (such as dash cam videos), remember: airbags do not deploy in all accidents! For example, in the event of a collision with a pedestrian or a collision in a parking lot, they may not be activated. Do not use such videos as a standard - rely on the data of your car manufacturer.

What to do after the airbags deploy

If the airbags in your car are deployed, follow the following algorithm:

  1. Assess the condition of the driver and passengers. Pillows may cause burns (from hot gas) or temporary disorientation due to the cotton.
  2. Turn off the engine and turn on the hazard lights. After activation the system SRS may be unstable.
  3. Don't touch the pillow bag - it is coated with chemicals (talc, reaction residues) that can cause skin irritation.
  4. Contact service. Even if everything looks intact, you need:
    • Replacement of deployed airbags and squibs.
    • Diagnostics of sensors (they could be damaged by impact).
    • Resetting errors in a block ECU.

The cost of replacing pillows varies:

- Driver/passenger: 15 000–40 000 ₽ (depending on model).

- Lateral: 8 000–20 000 ₽.

- Curtain: 20 000–50 000 ₽.

In a premium car (for example, BMW 7 Series) the price can reach up to 100 000 ₽ per set.

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If you are in an accident and the airbags do not deploy, but the car can be restored, keep all receipts for repairs. When selling a car, you will have to prove that the system SRS was restored professionally.

FAQ: Frequently asked questions about airbags

Is it possible to drive with a light on? SRS?

Technically possible, but extremely dangerous. A lit indicator means that the system is faulty and may not work in an emergency. Causes: broken wiring, faulty sensor or reset fuse. In some cars (for example, Honda CR-V) when the light is on ECU blocks airbag deployment.

How many times can one airbag deploy?

One time. Once triggered, the squib is destroyed and the cushion has to be replaced. It cannot be restored - it is a disposable device. Exception: some test cushions (for example, in training cars) are equipped with reusable gas cylinders, but this is not the case in production cars.

Is it true that airbags can deploy under heavy braking?

No, it's a myth. Sensors SRS react to sudden change in speed (deceleration), and not by pressing the brake pedal. For example, during emergency braking with 100 km/h up to 0 after 3 seconds the airbags will not deploy because the deceleration will be smooth. But the impact on the concrete wall 15 km/h can activate the system.

Is it possible to turn off airbags?

In most cars you can only turn off passenger airbag (for example, for transporting a child seat). There is a special switch for this (usually in the glove compartment or on the dashboard). Disable the driver's airbag without intervention. ECU You can’t - it’s prohibited by safety standards. Exception: some sports cars (for example, Porsche 911 GT3) allow you to deactivate the system for racing.

What happens if the airbag deploys without an accident?

It's called false positive. Consequences:

- A sharp bang and a cloud of dust in the cabin.

- Risk of injury (eg burns from hot gas or being hit by a bag).

- The need to completely replace the pillow and diagnose ECU.

Causes: short circuit, damaged sensors or firmware error. In some models (for example, Nissan Qashqai 2010–2013) there were massive recalls due to defective sensors.