Highways in the Sky Reply

On cool and clear afternoons in the San Francisco Bay Area, I often see jet contrails going north to south. I imagine passengers jets from East Asia or cargo jets from Anchorage, Alaska flying to Los Angeles (LAX). While it would be logical to assume these lines trace straight line paths between airports, aircraft fly slightly crooked paths through a series of predetermined way points. These airways are analogous to a highway system crossing the continent by linking major cities along the way.

Like the U.S. Interstate Highway System, air traffic control systems are based on 50-year old technologies, in the case of air traffic control, ground-based radars and voice communications over radio.