Originally Posted by teh603
Ultimately, the airlines are too cheap to take the obvious answer, as are the airports themselves. Most towers (at least as of 2003, when I read some articles on this issue) are still using 1950s equipment instead of modern, more efficient GPS systems.
The question you have to ask yourself is why? There are probably dozens of reasons why they are sticking to the older systems and a handful of reasons to modernize. It is a lot easier to build new infrastructure (e.g. in the 1950s when air transportation was expanding) than it is to replace operating infrastructure.