I was skimming the Codist blog when I read the following
One of my favorite data errors was when the latitude would be randomly in the 1000s even though the longitude was correct. MapKit would toss a fit so since I can’t know what the right value is, I just use 42 which puts the pin at the wrong location but at least it’s not crashing.
I just started laughing. Been there, done that, want it on a t-shirt. When collecting positional data from other sources, sometimes you just get bad data in. And in this case, 42 is the Ultimate Answer.
A while back I had written a data collection service that was collecting vehicle positions from onboard GPS device. Every now and then, the locations became random. This app was running in the continental US, any latitude/longitude values outside that range for that area were just ignored. In my case, any wrong location was unusable data.