Let's not hope so but it could happen. You are walking somewhere en all of a sudden you are getting dizzy, your legs seems to swoosh underneath you and you can not get anywhere. That is the time it is nice you can call someone who is close to you, or someone who knows of your situation.
Unfortunately I myself had that experience. Once in a while I have moments that I can not speak or move. Know whit this app I can just swipe once and tap a button on the Today screen and my girlfriend gets called and she knows exactly what needs to be done.
Very convenient for me it is not much trouble to call my girlfriend and I always know that help is nearby. And because this is a handy tool for me I can imagine that it can also help others.
In the app it is possible to select a phone number from your existing contacts. So be sure that the one you want to call is one of your contacts.
To get the full advantage of the app place the Today widget on your Today screen and place this widget on the top of your screen. That way you don't even have to unlock your phone to call your aid.
I truly hope that you never have to use the app but it is a reassuring thought that you can!