Last week a computer glitch required air traffic controllers to get flight plans by fax and type them into computers by hand. No lives were at risk and the problem itself was confined to the Northeast, but a lot of passengers were delayed and the incident dramatized how a 21st century system operates on 1960's technology. When cars and cell phones connect to global positioning satellites, why does air traffic control still depend on ground-based radar and radio? When $35 billion has already been spent, why is the Next Generation system so far behind? And, what's in store for this week of heavy holiday travel?