The New York Times has an article describing the urgent need for a GPS backup.  While this affects all users of GPS, it is a big concern for aircraft pilots who rely on GPS for safe navigation.  The FAA’s ground based navigation aids provide GPS backup, but the equipment is getting more costly and difficult to maintain.  

NY Times Headline:

The system is essential but also vulnerable. We need a backup.

The article quotes Todd Humphreys, an associate professor of aerospace engineering at the University of Texas in Austin, stating  “If we don’t get good backups on line, then GPS is just a soft rib of ours, and we could be punched here very quickly,” If GPS was knocked out, he said, you’d notice. Think widespread power outages, financial markets seizing up and the transportation system grinding to a halt. Grocers would be unable to stock their shelves, and Amazon would go dark. Emergency responders wouldn’t be able to find you, and forget about using your cellphone.