A lot of people seem to be down on this, citing GPS and other traditional numeric systems.<p>But I think this is much better for police specifically. For reasons that are not about data or systems so much as physical practicality.<p>Consider circumstances like these: A panicked hairdresser lost in the forest. An old person with progressing dementia; forgot where they were. A kidnapped child trapped in a room or locked in a car. Anyone in a burning building who can smell smoke. Try any of these situations when the cellphone is at 5%, or when the call keeps dropping, or when you can barely hear because it's so loud, or barely see, or you're drunk, your hand is broken, you're on drugs, you're dehydrated, you're hypothermic, you're bleeding, you're surrounded by buzzing insects...<p>Now think about the physical practicalities of a numbers system like GPS. To use any numerical system, you're talking about <i>memorizing</i> a string of eight or ten digits off one app and then reading them into a phone call. Yes, it may be possible to go on speaker and minimize the call app (if nobody is hunting you) but lots of people can't figure that out on their best day, much less in life-threatening situations. You have to be able to memorize it when you're afraid of death or shivering in the cold outside. Maybe the call gets disconnected and you have to go back, oh shit I closed the app, what was the number, oh I mixed up some numbers near the end, oh my god....<p>Almost anyone can remember three words without trying. A child can do it and my grandma can do it. Even if you get disconnected, it won't be hard to remember the words even minutes later. You can't miss a number, you can't transpose the numbers by accident because if you make a mistake it'll be obvious since the words aren't adjacent in the grid (for this reason). It's incredibly practical for the physical and mental constraints of a police situation, and that's why they use it.