Navy pilots report mid-air encounters with UFOs up and down East Coast

NEW YORK -- An investigation is underway after five Navy pilots have come forward to report strange unidentified flying objects spotted in the sky.

The pilots say they have had multiple mid-air encounters with high-flying, fast-moving objects that defy human capabilities.

The New York Times spoke with the pilots, who say they've all encountered UFOs during training missions up and down the east coast and noted the objects were "accelerating to hypersonic speed, making sudden stops and instantaneous turns, something beyond the physical limits of a human crew."

"Clearly this is nothing that we're used to seeing out there," former Navy pilot Ryan Graves said. "So we submitted a safety report, saying that there was an unidentified object in our working space, and we don't know what to do."

It comes on the eve of a new History Channel series called "Unidentified: Inside America's UFO Investigation," which chronicles a year-long investigation that includes former military intelligence officials speaking out on numerous reported encounters.

"We trust the American people to know that there are certain countries that have nuclear warheads," one expert says in the documentary. "And yet, we don't trust the American people to know that there's something in our airspace, and we don't know what it is."

The Navy responded to ABC News with a statement saying that in recent years, there's been "a number of reports of unauthorized and/or unidentified aircraft" in our airspace and that they've implemented new steps to report further possible incidents.

No one at Department of Defense is saying that any of these incidents involve the extraterrestrial, and many experts insist that "earthly explanations" can generally explain most of them.