On 26 September 1973, two Spanish Air Force pilots on a night-training flight near Valencia reported a powerful light apparently approaching their Mirage. They began their descent early to gain vertical separation, then thought the light was descending alongside them. A controller reported a brief radar echo only later in the sequence. The released file ultimately favours a probable observation of Venus, while preserving the earlier reports and a different explanation considered in 1973.
This is a separate incident from the better-known Manises diversion of November 1979. Its evidence is unusually useful for comparison: a next-day pilot report, a next-day controller report, a formal inquiry and a reassessment twenty years later. Reading them in order reveals where apparently straightforward phrases such as radar confirmation can overstate what the documents actually say.
The source and its two investigation dates
The Biblioteca Virtual de Defensa catalogue identifies file 730926 as the Valencia observation of 26 September 1973. The digital copy has fifteen pages. Its opening assessment belongs to the 1993 declassification review, followed by the 1973 reports and inquiry, and then astronomical calculations and a map. The order of the PDF is therefore different from the order in which the incident was investigated.
The catalogue records declassification under JEMA 5782 on 23 September 1993. That administrative date establishes the release decision, not a second sighting or a finding that the light was an extraordinary aircraft. The original reports retain their earlier dates. Names of the pilots and investigator are omitted in the released copy; they are described here by their roles rather than reconstructed from outside speculation.
What the Mirage crew reported
The complete released dossier includes a captain’s report dated 27 September 1973 on physical PDF page 5. The crew were flying a dual-control Mirage III-DE of Ala 11 on a training mission. Their stated initial position was on the Valencia TACAN 127-degree radial, forty nautical miles away, at 20,000 feet, at 19:24 Z. Z is the universal-time notation used in the report; it is retained here without converting it into an assumed local clock time.
The instructor first noticed a bright, strange light to the left. During the later inquiry, the pilots explained that the other captain had been flying by instruments and had not initially been looking outside. After his attention was directed to it, both agreed about what they saw. The observation was made with the unaided eye on a clear night when stars were visible.
They judged the light to be at roughly their altitude on a converging course. To separate vertically, they began the approach descent at forty nautical miles rather than waiting until the prescribed thirty-five. They then thought the light descended as they did, holding a similar heading and an apparent lateral distance of about four nautical miles. This distance was their visual estimate of a light, not a radar measurement of a resolved craft.
The crew described an initially brilliant white appearance that prevented them from determining a shape. The tone became reddish, and they reported apparent rapid movement westward as the aircraft reached roughly 7,000 feet. They heard no sound from it. These details describe a luminous appearance and perceived movement; the report does not supply a photograph or a separately measured trajectory for the object.
The radar report is narrower than confirmation
Physical page 6 contains the controller’s report, also dated 27 September. It says the aircraft reported an unidentified object following its manoeuvres, but no radar echo was initially visible. When the aircraft later reported that the object was turning towards the coast, the controller saw what he called a parasitic echo move in that direction and disappear almost immediately. The report does not describe a sustained tracked target throughout the encounter.
The pilots’ account says the controller told them about such an echo, which they associated with the light’s departure. The controller’s own statement is the better source for the sequence on the screen. It records an initial absence followed by a brief return. Treating the combined accounts as continuous visual-and-radar tracking would remove an important limitation present in the original evidence.
The paperwork also preserves a clock discrepancy. The controller writes 20:30 without specifying a time standard, whereas the crew gives 19:24 Z for its earlier initial observation. His report describes a later approach position, around twenty nautical miles and a roughly 135-degree radial. These entries should not be silently adjusted into a perfectly synchronised log. Different points during the approach may explain some positional differences, but the file does not provide a complete timed reconstruction.
What the 1973 inquiry considered
The correspondence on physical pages 7–10 shows the reports moving through the command structure during October and November. The inquiry then records questions to both pilots, air-traffic information and other checks. Its conclusions considered a bright celestial object seen by other pilots on nearby nights, or the landing lights of a commercial aircraft. Those were proposed explanations, rather than an identification made by the crew during the sighting.
The traffic information concerned a Comet travelling from Alicante towards Manchester. At about 19:12 Z it was offshore near Gandía, cleared towards Sagunto at 24,000 feet and estimating Sagunto at 19:19 Z. The investigator suggested that its landing lights might have been switched on to warn the military aircraft of its position. The inquiry also mentions an alert about possible deviations by aircraft from USS Franklin D. Roosevelt; it does not identify a particular carrier aircraft as the observed light.
The same inquiry reports that other night-flying pilots had seen a conspicuous point near the horizon in that direction. Their speculation about a solar-system object is evidence of another line of inquiry, not a precise astronomical identification. The 1973 conclusions leave alternatives open. The later review makes a more definite choice between them.
Why the 1993 reviewer rejected the airliner
The assessment on physical pages 2–3 argues against the Comet explanation using its expected position. If it was due at Sagunto at 19:19 Z, the reviewer reasons, by the 19:24 Z sighting it should have been to the right of the Mirage’s approach path. The pilots repeatedly put the light on their left. The review therefore rejects the airliner hypothesis instead of merely repeating the original investigator’s suggestion.
It also revisits the brief radar return. Because there was no initial echo and the later parasitic return disappeared immediately, the reviewer considers it probably just a spurious echo. He observes that the operators might not have attached importance to it without the pilots’ report. This is an interpretation of the controller’s account; the released material does not include a continuous radar recording from which UKPX could independently reconstruct the return.
The Venus calculation and its limits
The review supplies an astronomical alternative. Its attached AstroCalc Premier output on physical page 14 uses 26 September 1973 at 19:24 GMT and a ground reference of 39.48 degrees north, 0.37 degrees west. It gives Venus an azimuth of about 245.75 degrees, altitude about 0.86 degrees, brightness magnitude about −4.14 and a setting time of 19:28 GMT. These are the file’s calculated values, not a new calculation performed for this article.
The final map plots the inbound approach and places Venus to its left. It distinguishes a magnetic aircraft heading of 307 degrees from a geographical heading of about 301.5 degrees. Neither should be confused with the 127-degree radial used to describe the aircraft’s initial position. The reviewer regards the planet’s direction as approximately consistent with the pilots’ rather broad left-side description and concludes that Venus is a probable explanation.
There are limits to that assessment. The printed calculation uses a ground reference rather than the precise moving position and altitude of the Mirage, while the pilots’ four-mile estimate assumes a nearby object whose range was never established. The dossier supports a plausible astronomical identification, not a measured reconstruction proving how every apparent motion and colour change arose. Equally, a visual impression of matching descent cannot by itself establish that the light was physically flying alongside the aircraft.
What the record leaves us with
The value of this case lies in the preserved comparisons. The pilots took the light seriously enough to alter their descent; the controller did not initially detect a target; the original inquiry considered more than one ordinary source; and the later review rejected one explanation while strengthening another. The final status is a probable Venus observation in the released military assessment, with the underlying testimony still available for inspection.
The map point marks the public Valencia Airport photograph viewpoint at Manises as operational context. It is not an offshore sighting coordinate or a position assigned to Venus. The incident took place during an airborne approach, and the source’s estimated positions should not be turned into a false exact encounter pin.
Source credit: Fuente: Biblioteca Central del Ejército del Aire y del Espacio / Biblioteca Virtual de Defensa. The complete fifteen-page released copy was read; the pilot and controller reports, calculation and map were also checked visually. This original English paraphrase and comparison adapts the licensed digital material under CC BY 4.0. No AstroCalc software image is reproduced. Related reading: Manises, 1979 and UFO / UAP. Checked 5 November 2026.