Cairn makes it easy to find cell coverage in the outdoors and keep your loved ones up to date on your plans and progress. If you’re overdue, we give your safety contacts recommendations on how and when to contact search and rescue. You can also use Cairn to download maps and trail information, including trail distance, elevation gain and travel ETA.

Will Cairn work if I lose cell reception?

Yes! Cairn is designed to work offline, but it really helps if you download the map for the area you'll be exploring before you lose reception. Our safety notification feature only works if you set it up before you're out of range. But rest easy knowing that your safety contacts will be alerted if you're overdue, regardless of your phone's status.  

my loved one is overdue, what should I do?

Try to contact them by phone, and reach out to any other contacts on your notification message. If you are worried for their safety, we recommend you contact authorities. In most cases search and rescue teams prefer getting notified as early as possible. Search and rescue teams have stressed to us how important this is.  

Is Cairn Free?

Yes! It's free to download and use. In addition, we have a Premium membership that allows you to use all the latest features and services. Currently we offer free access to the premium features for your first 30 days. At the end of the trial period there is no need to cancel anything; simply sign up for Premium membership if you'd like to continue using those features, Premium features include:

  • Sharing your real-time location with your safety contacts

  • Downloading maps from anywhere in the world for offline use

  • Recording and saving your trail & trip stats (iOS only)

  • Accessing driving directions to the trailhead

If you do subscribe, you can cancel your Premium membership through your phone's Settings app. After the trial period you will still be able to see cell coverage on maps and view trail info such as distance, elevation, and estimated time of arrival.

Does cairn drain my battery?

Cairn does use some battery if you've sent out a safety notification, but we are working on decreasing consumption all the time. We have found that putting your phone into low battery mode offers significant battery savings. However, on some devices this may decrease the number of spots where your location is collected and shared with your safety contacts. On multi-day trips we recommend carrying a small battery pack (we do!). Tracking the stats for your trip is more battery intensive, and we recommend using the stat tracking feature only when you are moving. (Stat-tracking is an iOS-only feature.)


Yes, you can tap on a point to see which carriers have coverage (or not) at that point. Although we have millions of data points worldwide, we don't have data for every carrier (or every spot, for that matter) as this data is crowdsourced by other adventurers who use Cairn. 

Can I make emergency calls via other carriers?

Yes! You may be able to make an emergency call (to 911, for example) even if your carrier doesn't have coverage. Your phone just needs to operate on the same frequency band as a carrier that does have coverage. Always try to call 911 in an emergency, even if it doesn't look like you'll get through.


The Android version is currently in the beta-testing phase! If you'd like to be notified when we release it or take part in our beta test, just pop your email address into this form.


Yes! For those of you with an Apple Watch, you can send an I'm OK message with just two taps on your watch. You can also end your Cairn and see a snapshot of your location relative to your destination.

What happens when I put my phone in airplane mode?

Unfortunately we can't tell the difference between airplane mode and no service. So any data you collect when in airplane mode will be recorded as no coverage. However, we know that using airplane mode in the backcountry saves your battery. And so we take this into account in our coverage aggregation algorithm for an area. Please use airplane mode as you normally would, but know that it will be recorded as no coverage. 


Absolutely. And the rest of the ten essentials as well! Cairn is just another tool to throw in your cache of safety gear. We are not advocating that you use your phone at every opportunity, and we get that you probably want some peace and quiet when you're out. But the vast majority of modern day wilderness rescue operations are initiated by mobile phones.


Phone batteries don't like the cold and your phone will shut itself off even if it still has charge. Some people keep their phones in their inside jacket pockets, or slip in a hand-warmer to keep their phone batteries warm.

HOW can i help gather more data for the coverage map of the wilderness?

The best way is to get more people using Cairn. You can invite people via Twitter or Facebook using our handy links. If you're a member of a Facebook or Yahoo outdoor group, please share this website there. We can use all the help spreading the word that we can get. 

My question isn’t answered here. Now What?

Please email us at We’re anxious to help.