Now UPS is testing a technology designed to close that gap and, possibly, bring sweeping new efficiencies to the entire air traffic control system without compromising safety.
Droppings that looked like panda scat were collected and brought back for testing, and the results confirmed that after a gap of 20 years, pandas have begun their return to the valley.
This plane, which AeroVironment hopes to start testing by next spring, is designed to fill a surveillance gap that military and intelligent services are desperate to address, so-called persistent surveillance.