Since the popularization of smartphones by way of the iPhone in 2007, outdoor use of smartphones has increased. As a passionate hiker and IT guy, I want to give a little primer on how to use a smartphone to simplify our (outdoor) lives and what to consider.
My perspective is that of a hiker doing day and long distance trails in very common but also very remote areas, in the mountains or flatlands.
This article contains some recommendations on how to prepare and how to use the phone when being out there, divided in what to do before the trip, at the start of the trip, and during the trip.
It is advisable to not only rely on general map sources like open street maps or google maps, but research if there are other applications. These are often country- or even region-dependent.
When visiting a foreign country, it is advisable to not only rely on general map sources like openstreetmaps or google maps, but research if there are other applications. E.g., for Switzerland there is swisstopo, for Norway there is ut.no, etc. Consider that some map applications do not allow offline use and therefore become practically useless for certain areas.
When the favourite maps are not available as an app, you often have the possibility to download them in PDF format. In the worst case, make screenshots of the relevant regions and save them on the phone.
The issue of depending on an extremely complex and sensitive piece of hardware can be mitigated by being aware what alternatives are there and to what level it is required, anyway. One should not be mislead about the robustness by personal experiences ("I dropped my phone five times already and nothing happened") or marketing (military-grade protection).
A helpful rule of thumb is that devices are most prone to fail at the beginning of their lifetime, followed by some time of reliability. With increased age the chance of failure increases again. I.e., neither take a phone you just bought last week, nor the five year old one which was already dropped five times on the floor.
In general, be always prepared for the smartphone to fail and do not depend entirely on it for important tasks:
Always prepare that you might drop your phone, as being exhausted or in difficult terrain complicates phone handling.
Consider that outdoor surfaces are different than man-made ones. Those are generally right-angled; urban life rarely poses a danger to phones with a case since corners and edges always hit ground first. Outdoors, irregular surfaces like gravel and rocks make a drop on the screen more likely. A solid screen protector is the most useful impact protection after having a case.
Check the smartphone's dust and water protection by consulting the manufacturer's specification and research what this specification (MIL or IP with attached number) actually means. If there is no protection, consider taking a sealable plastic bag for transport or a specialized bag which can be used with touchscreens.
Rivers, deep lakes and abysses, unreachable gaps between stones, make irrecoverable loss of a smartphone a considerable risk (yes, I already dropped a tablet into a lake and never got it back). Attach a cord to the phone and re-consider your behavior when and where you handle a smartphone.
Battery behavior can be weird, in particular when the battery is old. It is common to have the battery being shown to be at 20%, but then suddenly drop dead. Or the other case, show 1%, but remain there for hours. The level is just an approximation based on the battery's voltage and learned behavior.
The best way to understand this behavior and to let the phone re-calibrate the battery level it shows is to let the phone run dead once or twice.
The same holds for powerbanks, if you take one with you. Use it for charging your phone for some time to let it run dry and know its actual capacity.
A rough check whether you will be able to connect to the cell network at all is to check a coverage map. You will find those often on the websites of the big mobile network providers, like e.g., Swisscom and Sunrise.
Weather forecasts are incredibly helpful on multi-day tours. Often local weather forecast services exist that are more reliable and precise than the generic global ones, like yt.no for Norway or MeteoSuisse for Switzerland.
Some applications automatically (and without user control) store data temporarily, i.e., caching them. An example is the UT.no app. One cannot download certain map tiles, but when looking at them, the app will automatically store them. Once one figured out this pattern, one can download the required maps by zooming in to the max level to cache and use them offline. One has to always be careful though, since you never know how much an application will cache. At some point it might start deleting older map tiles, especially between restarts of the app or the phone.
Being offline means, well, that you cannot access any online data. ;-) Some map apps allow you to download map data so you can use it offline (OsmAnd, swisstopo). But also entertainment is a nice to have. Magazines can be downloaded as PDFs, browsers support saving websites offline, videos and podcasts can be stored offline on the phone as well.
Often phones have hidden features you do not know but which might come in handy. E.g., some phones can wirelessly charge other phones, which might be helpful when you encounter somebody with a dead phone and no fitting cable. Vice versa when your phone has wireless charging. However be aware that wireless charging is less efficient than wired charging.
Especially in huts with other people, expect all kinds of different USB ports and no fitting cable. There are cheap adaptors with all common connectors and virtually no weight for about 1CHF.
Prepare your smartphone in the same way as you apply sunscreen shortly before starting a hike.
Especially on short multi-day trips one can easily survive with one battery charge when the phone is not much in use. With the now mentioned energy saving measures, my phone would not use more than 10% of battery in a day.
A mobile phone is constantly in exchange with the base stations of the cell network to be available to incoming calls and to transmit data. Communication with the cell network is the main energy drain of an idle phone!
With a weak signal, the phone requires more energy for the transmission of data so it is still received by a farther away cell tower (including just being connected to the network). This is the e.g. the case in rural regions and a sparse distribution of cell towers; or in a train or bus at high speeds; or deep in a building or gorge with walls to attenuate the signal.
The strongest way to prevent this is to go into flight mode. This means nobody can call you and you will not receive messages and you should be aware of the safety implications, as noted in emergencies.
Less strict is to switch off data. In this case, no data is sent, but you will still be receiving calls and sms.
If you do not want to switch off data, at least switch off wifi and bluetooth.
A smartphone is full of applications performing actions in the background. This is messengers like signal or whatsapp constantly checking for new messages, or the music player searching for new music. All these tasks consume power.
The energy saving mode will among other measures (decreasing display brightness, etc.) stop background processes from running.
Applications in the foreground ("visible on th escreen") are not blocked by energy saving mode and generally can perform energy-intense tasks. Close all foreground applications when possible (e.g., for navigation, it does not work). This can be done in the app overview/app switcher.
Communication with external devices like headphones, sport watches, cameras requires power. Keep the use of these devices as low as possible to save energy.
As detailed in Get a cell network signal, there are certain points where the cell network is likely available. If you want to have network access, consider these points by looking at the map to find the places where it is most likely.
Getting a cell network signal is mandatory for communication (phone calls, sms, internet).
The best case is a direct line of sight between the phone and a base station in clear weather. Deriving from this scenario will decrease the signal strength and therefore range and might lead to the phone disconnecting (i.e., no cell network being available).
Therefore, to get the best coverage:
Consider also that bad weather will decrease signal strength since humidity and rain attenuate. But in summary, topography is the main consideration; high points and civilization in sight are good, gorges and uninhabited valleys the worst cases.
In contrast to the cell network, satellite navigation (GNSS) works by seeing as many satellites as possibles. GNSS is based on receiving the signal of multiple satellites in positions which should be as diverse as possible. Therefore, the direct line of sight statement becomes the statement that you should see a big amount of sky to increase the amount of satellites, the span of their positions, and for how long they are seen.
Anything decreasing the amount of sky your smartphone sees, will decrease the signal strength. This includes yourself bending over the phone, the roof of the hut you are in, the coating of the window you are looking out of, rain and clouds covering the sky, or the mountain or tree trunk next to you.
A bad GNSS signal will not necessarily lead to a complete fail of the localization, but precision might be reduced; often intransparent to the user. Even under good conditions, depending on the smartphone model and the received signal, the position might be off by several tens of meters! Take this into account when the smartphone tells you that you are on a trail you do not see, as it might actually be twenty meters above you...
The main concept with modern phone messaging (threema, signal, whatsapp, etc.) is opportunistic communication: The communication happens whenever there is an opportunity.
When the smartphone is online, messages transmit in near real-time. But when the phone is offline (due to having no cell network or being in flight mode), one can still look at messages and send new ones. These will only be sent once the smartphone will go online again, and only at that point will messages from others written in the meantime be seen.
Internalize this pattern to communicate optimally. You can e.g. write messages to your friends in flight mode in a warm hut, and send them out once you are on a cold and windy peak where you switch off flight mode for a short time, receive their messages, and update the weather forecast. Since also connection might go on and off and is generally more stable when the phone stays fixed, just leaving it at a window for ten or twenty minutes might help in establishing communication.
But when you have not been online for a while, remember that you only see old data. The weather forecast for tomorrow might be inappropriate since it was only generated three days ago, and the last message you see from a friend is not the last one, just the last one you received.
Since you might have a weak signal, you might only have poor bandwidth. Some applications do not work at all under these circumstances, others might be unusably slow. Android phones have a data saving mode. to deactivate background data usage, shutting off all the apps transmitting data in the background. In this mode, messengers will not receive new messages unless you open them and have them on the screen, but you will also have the full bandwidth available to whatever your foreground application is.
If you are in a rush or in a foreign country where you need to save data volume, you can use the data saving mode. Otherwise, I recommend to leave it off due to the unwanted side effects of several apps not receiving data anymore unless explicitly opened.
The probably most important part in this article comes last so that you have read the previous parts already and can make more sense and appropriate decisions. The use of a phone in emergencies cannot be understated to call for help, look up information, locating yourself or others. In an emergency, but also when you encounter a dangerous situation, think about the situation and how to apply the aforementioned patterns.
Store the phone in an appropriate location and change it when necessary. In difficult situations, store it close to the body and easy to reach and make sure it cannot be lost. E.g., when crossing a river, it is not very helpful when the phone is in the backpack and swims away together with it...
Consider that smartphones, even when protected against humidity, cannot be operated via their touchscreens when wet. In heavy rain, it might be impossible to store the phone in a dry place and the hands will also always be soaked. So prepare to not be able to use your phone under bad weather conditions.
One major consideration when using the phone for communication (phone calls, internet) is whether cell network is actually available, as detailed in Get a cell network signal. In an emergency you might not be able to do a phone call and you might have to leave your position to be able to go online.
If you followed the previous recommendation to go into flight mode for extended battery life, switch off flight-mode in dangerous situations. For one, registration to the network takes a while. On the other hand, if you are unconscious or otherwise disabled, you might not even be able to make a call.
However, the phone can still help in being located. Search and rescue organizations use mobile IMSI catchers to locate people: These devices act as base stations; your phone will register to them when they are in reach. Even without a cell network, your phone can register to a passing-by airplane or helicopter and therefore help locating you.
At the time of writing, June 2023, some companies integrate satellite services for emergency communication in their high-end smartphones. These phones enable you to place emergency calls even when out of reach of the network. Still consider visibility of the sky as an important factor, as mentioned in Get a GNSS (GPS) signal
A smartphone is a great help and reduction of weight compared to earlier times when one had to carry several heavier devices for the same functionalities. As a replacement for an emergency flashlight, a camera, a handheld GPS or a map, a weather forecaster, it is a great help. This article was written in June 2023 and reflects the technical knowledge at that time.