Burning on Fort Itaipu Sentinels
 The incident
At 2:00am, two sentinels of the fort noticed an intense brightness in the sky, described by the them as a 30-meter wide circular UFO, descending at high speed towards the fort. At about 300 m (1000 feet) above the fort, it stopped.
The UFO then started to emit a strong humming, and an intense heat wave hit the sentinels, even though there wasn't any visible flame or light. The sentinels were overcome and their clothes caught fire. Both were armed with sub machine guns, but they didn't shoot the UFO, nor did they raise the alarm. One of them fainted; the other took cover under a cannon. Their screams alerted the other troops, and the power went out. The fort's entire electrical service was affected: the lights, the electronics which controlled the gun turrets and elevators, and the communications system. The emergency circuits were switched on, but they failed as well.
A minute later, the lights and power came back on and the heat wave ceased. The soldiers ran to their stations, and some were able to see the UFO climbing vertically and then moving away from the fort at a rapid rate.
The burned and shocked sentinels were taken inside the fort and received medical attention, suffering from first and second-degree burns in 10% of their bodies. A few days later the two were taken by a military plane to Rio de Janeiro, where they were treated at the Central Hospital. They were kept in isolation by military security.
The fort's commander sent a message to the head quarters of the Brazilian Army. As the United States had more knowledge about UFOs, Brazilian authorities asked the American embassy for help on the investigations. Brazilian Army and United States Air Force personnel, along with investigators of the Brazilian Air Force, flew to the fort to interview the soldiers.
After listening to the sentinels' descriptions of the UFO and of the situation, the investigators discussed why the sentinels were attacked. To date, the Fort Itaipu incident still remains without any official explanation. An official of the USAF, searching for the reason which lead the UFO to attack the sentinels, reminded of a report by Project Sign in which members expressed their beliefs about an advanced race that has been observing Earth. He expressed his opinions on the case:
"Such civilization could see that in Earth we now have atomic bombs and that we are quickly improving our rockets. Given the past history of mankind - frequent wars showing a belligerent human race - they must have become alarmated. We should, therefore, expect, specially at this times, to receive such visits. According to this, the main objective of the aliens would be to watch our space improvements, fearing we could become a threat to other planets. If this hypothesis is exact, it could be expanded to link the launching of the Sputniks with the attack to the Fort Itaipu. However, this sounded absurd for all investigators. It would mean that the aliens would be worried about our firsts steps in space, and by small space ships so primitive that would look like a canoe if compared to a transatlantic liner. It would also mean that those burnings had the purpose of demonstrate the superior weapons they could use against the aggressive explorers coming from the Earth. However, we were still far from the piloted space flight, even to the Moon. According to the human logic, we would not be able to threaten a superior space ship - not now nor later."
 See also
- Lorenzen, Coral E. (1966). Flying Saucers: The Startling Evidence of the Invasion From Outer Space. New York. pp. 156–157.
- Carpenter, Major Donald G.; Lt. Colonel Edward R. Therkelson. "Introductory Space Science - Volume Ii". Department of Physics of the USAF. Retrieved 27 October 2012.
- Fort Itaipu UFO Incident rr0. In French
- E. Keyhoe, Donald (1977). A Verdade sobre os Discos-Voadores. São Paulo. p. 29.
- Fort Itaipu UFO Incident - Revista Vigília (Portuguese)