>Until just a few years ago, the satellite communication system used by jetliners didn't include data on an aircraft's location in the pings, the electronic equivalent of handshakes used to establish initial contact.
I have a personal rule to date-time stamp all data collected from experiments. I'd add GPS if my experiments weren't all stationary. The extra bit of meta-data is a lifesaver if I do something dumb and have to reconstruct what I was doing when I collected the data, for instance correlating the data with my notes or other information that I gather.
