One of the great perks of flying privately is right there in the name: privacy. But the ability to stay away from prying eyes only applies inside the cabin. Social media accounts that broadcast flight patterns of noteworthy names—including Tom Cruise, Kim Kardashian and LVMH chairman Bernauld Arnault, as well as numerous sanctioned Russian oligarchs—have racked up millions of followers combined, with the Twitter handle @elonjet gaining national attention after Musk himself suspended the account. The spotlight it shines is equal parts geeky hobby, gawker-level curiosity and data-driven emissions-shaming—and Arnault, at least, eventually got sick of the glare, selling his Bombardier Global last fall and switching to charter flights with private passenger manifests.

And it’s not just business magnates, celebrities and politicians who are vulnerable. Anyone using a private jet is sharing information transmitted through the plane’s black box. For safety reasons, Automatic Dependent Surveillance–Broadcast (ADS-B) technology transmits GPS coordinates, altitude, ground speed and other data to air-traffic controllers and surrounding aircraft—but it also gives rise to dangers ranging from corporate espionage to violence.

“It’s akin to driving on the interstate and having anybody pick up your license plate to see who’s in the car and where you’re going,” says Doug Carr, senior vice president of safety, security, sustainability and…