The Ota Air Base Incident (1982)
On November 2, 1982, Lieutenant Júlio Miguel Guerra, a Portuguese Air Force flight instructor, was piloting a Chipmunk trainer near Ota Air Base, north of Lisbon, when a metallic two-hemisphere disc, marked by a gridded central band, began circling his aircraft for nearly thirty minutes at over 1,500 meters altitude. Two other pilots flying separately reported the same observation.
Witnesses
3 Portuguese Air Force pilots
Why it endures
One of the largest military investigations ever conducted into a UFO case in Portugal, with three independent pilot testimonies and unconditional access granted to civilian investigators by the Air Force Chief of Staff.
Official version (contested)
The Portuguese Air Force never identified the object; the file remains one of the rare cases worldwide where complete military records were made available to independent investigators.