[bickfordb]

Seems like you would get an excellent picture of everyone's location habits with a small number of flights per city per month.

If this is legal, why can't they just subpoena carriers for the tower census data?

[mike_hearn]

They could try, but they might not get it, and the carriers wouldn't like it - better to ask forgiveness than permission, right? I think it says this in the article.

[couchand]

Not as reliable.