Estados Unidos / Mar de Filipinas.USS Hassayampa · radar and lights over the Philippine Sea (1965)

In May 1965, the USS Hassayampa, a US Navy fleet oiler supplying the Seventh Fleet, was sailing west across the Philippine Sea, some thousand kilometres east of Luzon. On 5 May at 11:45 GMT —around 20:45 ship's time—, at position 20°54′ N, 135°30′ E, the officer of the deck and all bridge personnel saw two objects pass from east to west at extremely high speed. They were of first magnitude and kept the same position relative to each other. About thirty-five minutes later, the same or identical objects passed again, this time from west to east and again very fast. They were seen with the naked eye, but radar did not pick them up and their altitude could not be determined.

The second episode, the next day, was the important one. On 6 May at 09:10 GMT —around 18:10 local—, at position 20°22′ N, 135°50′ E, the signalman on watch reported what he thought was an aircraft. Through binoculars three objects were seen close together, one of first magnitude and two of second, approaching the ship at high speed. At 09:14 GMT, the SPS-6C air-search radar detected four moving targets, at ranges up to 22 miles, and held them for up to six minutes. According to the message, on reaching the ship the objects spread into a circular formation directly overhead and stayed there for about three minutes, a manoeuvre observed both visually and on radar; the brightest, which hovered off the starboard quarter, gave the largest return. The objects changed course several times, were tracked at speeds "in excess of three thousand knots" and did not answer the IFF identification-friend-or-foe challenge. They then moved off to the south-east at high speed. It was seen by the commanding officer, all bridge personnel and "numerous hands topside".

The Hassayampa's message, addressed to the Seventh Fleet command and to the 13th Air Force at Clark Air Base (Philippines), copied to the Chief of Naval Operations and the Pacific Fleet command, added a third paragraph: between 5 and 7 May, from 18:00 to 20:00, other objects were seen with all the characteristics of a satellite, and the crew stressed the "marked difference in speed and manoeuvrability" between those assumed satellites and the objects of the first two episodes. The message was distributed to the Joint Chiefs of Staff, the CIA, the Defense Intelligence Agency and the National Military Command Center, among others.

On 14 May, Captain David G. Robinson of the Defense Intelligence Agency in Washington asked Major Hector Quintanilla, head of Project Blue Book, for an informal evaluation. Blue Book computed the passes of the Echo I and Echo II balloon satellites, the most visible of the era, and found that neither passed over the area at those times. On 28 May it replied that the most likely cause was an aircraft, but that the data were "too incomplete and conflicting for analysis": the reported duration and speed were incompatible with each other, and the range and visual characteristics seen through binoculars did not agree with the report either. The official record card classifies the three episodes separately: insufficient data, likely aircraft and probable satellites (other than the Echoes). "Without additional data," it concluded, "all we can do is speculate."

It is one of the best-documented naval cases of the 1960s: a Navy ship, two days running, with dozens of military witnesses, a radar contact matching what was seen and an official message that reached the Joint Chiefs of Staff and the CIA. It also has something unusual: the crew itself distinguished the satellites it saw every evening from what troubled it, and said so in writing. That rules out the easiest explanation for fast lights in the evening sky, and Blue Book ruled it out too with its Echo calculations.

But the weakness of the case lies in the same document, and Blue Book pointed it out well. A target at more than three thousand knots covers 22 miles in under half a minute, so it cannot be held for six minutes on a radar with that range; and objects that look like first- and second-magnitude stars through binoculars do not square with a radar return a few miles away. Something in the report was mismeasured or mistransmitted. The 6 May episode, moreover, happened around 18:10 local, at twilight, when high objects still catch sunlight and high-flying aircraft can shine like stars; the SPS-6C, an air-search set of the period, was not reliable for measuring the speed of targets that change course. A group of military aircraft —friendly ones not answering IFF because it was not switched on, or another country's reconnaissance aircraft— explains the return and the formation well, though not the reported speed.

The case also shows how the system worked in 1965. The message from an oiler reached the Defense Intelligence Agency, which did not analyse it itself but asked Blue Book for an informal opinion by telephone, and Blue Book answered with a routing note. Nobody interviewed the witnesses or asked for the radar logs. That is why the case weighs mainly on indeterminacy and on the mundane explanation, with weight for friendly or foreign military aircraft, and a remainder for the non-human because of the combination of witnesses, radar and manoeuvres that the report describes and nobody investigated in depth.