If the phone's off, that's going to be less useful. And the tower-tracking location granularity's much lower than GPS Though I don't know what the reporting intervals are. Some smartphones (or their apps) were reporting location data every 10 seconds, with accuracy measured within a few feet.
Can't find that article at the moment, though another reports that location information is logged "at least several times an hour":
Here: "In a six-month period — from Aug 31, 2009, to Feb. 28, 2010, Deutsche Telekom had recorded and saved his longitude and latitude coordinates more than 35,000 times."
Except in certain situations when you're probably pretty lucky to have it on.
I had a friend who ran off the side of a mountain in Colorado. He called 911, but had no idea where he was (he was from the Midwest). Within about 40 minutes, they had triangulated his location and had a tow truck and emergency vehicles routed to get him out.
Without his phone and the ability to locate him, he was pretty sure he wouldn't have made.
If he's called 911 then ipso facto 1) his phone is on and 2) all location features are activated (on pretty much any phone of recent memory), as dialing 911 enables just this.
The fact that the exception proves useful doesn't mean my phone should transmit and the telco provider, app manufacturers, and others record, possibly indefinitely my location data every few seconds.
If you haven't read Maciej Cegłowski "The Internet with a Human Face", do. It's quite simply one of the best and most completely cogent arguments against the advertising-supported services model I've seen ever and anywhere. He's "idlewords" here on HN.
While it is obvious that turning off the phone helps, it's good that you make that point as I cannot remove the battery from my smartphone, a problem most "dumb" phones don't have.
Can't find that article at the moment, though another reports that location information is logged "at least several times an hour":
http://online.wsj.com/news/articles/SB1000142405274870398370...
Here: "In a six-month period — from Aug 31, 2009, to Feb. 28, 2010, Deutsche Telekom had recorded and saved his longitude and latitude coordinates more than 35,000 times."
http://www.nytimes.com/2011/03/26/business/media/26privacy.h...
That's every 7.5 minutes.
I only wish I knew who I was hiding from ;-)