When you need to get someone’s attention over great distances in air, on land or sea, the fastest way to communicate is with light. Light signals have evolved over centuries from lamps and lenses to sophisticated lasers that act as warning systems, signal intent, and establish perimeters.
That’s why the U.S. Air Force, after the attacks of September 11th, 2001, rapidly implemented a laser light system to protect the nation’s airspace by flashing colored lights into a pilot’s cockpit to warn about restricted areas.
It’s known as the Enhanced Regional Situational Awareness (ERSA) system, and after 10 years in the field the lasers needed refurbishment. But they couldn’t be out of order anywhere for any length of time.