Each probe can pick up GPS signals and signals from eLoran, an enhanced version of Loran, the ground-based terrestrial radio-navigation system first used by the American and British navies during the second world war.

ECONOMIST: GPS jamming

Enhanced-vision technology relies on infrared to produce a real-time view of the ground, sensitive enough to pick up a deer or a person from 1, 380 feet up in foggy conditions.

FORBES: Magazine Article

In the days and weeks before each Honor Flight, an army of ground volunteers coordinates every detail of each trip -- from the buses that pick them up to the meals they eat.

CNN: STORY HIGHLIGHTS