January 2021: FAA pilot reports have revealed that military tests are interfering with airline flights. The military is presumably generating GPS interference to test their latest positioning technology, but the interference is reaching beyond the test sites and jamming passenger aircraft that routinely rely on GPS for navigation and landing. Although pilots are trained for such scenarios, the loss of GPS is so rare that it can still cause disorientation and confusion in the cockpit. In this article from IEEE Spectrum, Dr. Humphreys explains: 

"I don’t blame pilots for getting a little addicted to GPS. When something works well 99.99 percent of the time, humans don’t do well in being vigilant for that 0.01 percent of the time that it doesn’t."