What is crash detection and how does it work?

From smartphones to smartwatches and family safety apps, crash detection technology is quietly becoming a vital part of modern driving. But how exactly does it work? What sensors are involved, and how reliable is it when every second counts?

We’ll break it down in simple terms, explain how it helps families stay safe, and offer tips on making the most of it, especially if your teen is just starting to drive.

What is crash detection?

Crash detection is a safety feature that automatically senses when a car accident has occurred and can notify emergency contacts or emergency services. You’ll find it on certain smartphones, smartwatches, and family safety apps, like Greenlight, the #1 family finance and safety app*.

In the event of a detected crash, your device may:

• Sound an alarm

• Display an alert with an option to call 911

• Automatically contact emergency services if there’s no response

• Share your real-time location with selected contacts

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It’s designed to help during those moments when you might be unconscious, injured, or simply too shaken up to call for help.

How does crash detection actually work?

The feature relies on several built-in sensors and data sources working together. Here’s a look at what powers it:

Accelerometers and gyroscopes

These measure sudden changes in speed and orientation. If your device detects a rapid deceleration (as in a collision), it flags the incident.

Microphones

Some systems listen for the distinctive sounds of a crash, like metal-on-metal impact or airbags deploying.

GPS

Your location helps confirm a sudden stop, unexpected movement, or deviation from typical driving routes. It also provides critical data to emergency responders.

Barometer

A change in air pressure can signal that airbags were deployed or that a window was shattered, which adds another layer of confirmation.

Machine learning and algorithms

These systems combine all the inputs mentioned above to make a determination. Over time, they "learn" what constitutes a real crash versus a false alarm, helping reduce unnecessary emergency calls.

Who uses crash detection?

Crash detection is increasingly found in:

• Smartphones and smartwatches with advanced motion sensors

• Vehicle telematics systems (built-in or aftermarket)

• Family safety and location-sharing apps

The technology is evolving quickly, and many modern devices now include this feature automatically. Some require opting in or enabling permissions, so it’s worth checking your settings.

Is crash detection reliable?

While no system is perfect, crash detection is generally effective in recognizing serious car accidents. However, it can occasionally trigger false alarms. Some common false triggers include:

• Dropping your device

• Sudden braking without an accident

• Participating in intense activities like skiing or mountain biking

Most systems account for this by displaying an alert and giving users a short time window (often 20 to 30 seconds) to cancel the emergency call. If there’s no response, the system proceeds to contact help.

To make the most of crash detection:

• Keep your device charged and accessible while driving

• Enable permissions for motion, location, and emergency access

• Set up your emergency contacts in advance

Why crash detection matters for families

For families with teen drivers or senior loved ones**, crash detection offers added peace of mind. It acts as a backup in those critical moments when someone might not be able to call for help themselves.

If your child is learning to drive or commuting solo, knowing that an emergency call can be made automatically can help relieve stress. It’s not a replacement for safe driving habits, but it is a helpful safety net.

That’s where Greenlight comes in. Greenlight goes beyond financial tools by offering built-in family safety features, including crash detection*. When a crash is detected, Greenlight can send automatic alerts to parents or guardians with real-time location updates*. Combined with driving behavior insights and trip history*, it helps families stay connected on the road, without the need for constant check-ins.

Keep your teen driver safe! Protect them with Greenlight’s money and safety app. From crash detection to emergency alerts, we have your back. Try Greenlight, one month, risk-free.†

This blog post is provided "as is" and should not be relied upon as a substitute for professional advice. Some content in this post may have been created using artificial intelligence; however, every blog post is reviewed by at least two human editors.

*Requires mobile data or a WiFi connection, and access to sensory and motion data from cell phone to utilize safety features including family location sharing and driving alerts and reports. Messaging and data rates and other terms may apply.

**Loved ones refers to covered family members as defined in the policy i.e. supported adults for which you control or assist with their finances.