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On the morning of June 21, 1976, 20-year-old student pilot Rafael Pacheco Pérez took off from Mexico City International Airport in a Cessna 150 for what was supposed to be a routine 25-minute solo training flight. Less than two minutes after departure, the aircraft vanished from radar. Exactly one hour later, Pérez contacted air traffic control from Acapulco—over 400 kilometers away—reporting confusion and no memory of the journey. The incident, which involved an unexplained transmission and a fuel tank that remained nearly full, has never been officially resolved. What follows is a detailed reconstruction of the event, drawing on official records, witness statements, and subsequent investigations.
Pérez was enrolled at the Escuela de Aviación de México, a civilian flight school operating from a hangar on the eastern side of the airport. Founded in 1962 by a group of former military pilots, the school catered primarily to middle-class students aspiring to careers with Aeroméxico or Mexicana Airlines. Its curriculum followed the standard DGAC syllabus: 40 hours of ground school, 50 hours of dual flight, and progressive solo exercises. The hangar itself was a utilitarian structure of corrugated metal and concrete, painted with a faded Mexican flag motif. Inside, chalkboards displayed weather charts, and a small fleet of Piper Cubs and Cessnas lined the apron. Pérez, known to classmates as “Rafa,” was unremarkable in demeanor: polite, methodical, and slightly reserved. He came from a modest family in Colonia Roma; his father worked as a bookkeeper for a textile firm, and his mother took in sewing. Flying was his escape from a predictable future in accounting. He had accumulated 52 flight hours, all under dual instruction with Captain Luis Morales, a 15-year veteran of the Mexican Air Force who had transitioned to civilian instruction after retiring from active duty. Morales described Pérez as “cautious but competent,” noting in the logbook that he handled crosswind landings well and maintained altitude within 50 feet. The first solo was a milestone every student anticipated with a mix of pride and anxiety. The planned route was straightforward: depart runway 5R, climb to 
3,000 feet, fly east over the former lakebed of Texcoco—a vast, cracked expanse of white salt flats that had once been a lake in Aztec times—circle the municipality of Chimalhuacán with its cluster of low brick houses and cornfields, and return to the airport. The loop covered roughly 40 kilometers and was designed to build confidence in navigation by visual references. The Cessna carried 12 gallons of 100LL aviation fuel, sufficient for about 90 minutes of flight at 75% power plus a standard 30-minute reserve, which was more than enough for the short exercise. The aircraft had undergone a 50-hour inspection two days prior, with no discrepancies noted. Weather conditions were favorable: clear skies, visibility exceeding 10 kilometers, and light northerly winds of less than 10 knots. The 7:00 a.m. METAR from Mexico City reported scattered clouds at 25,000 feet, temperature 18°C, dew point 12°C. No turbulence or wind shear was forecast. The airport was operating normally, with commercial jets on the main runways and training traffic confined to the eastern sector. At 8:15 a.m., tower controller Ana Luz García, a 28-year-old with four years of experience, issued takeoff clearance in routine fashion: “Cessna Zulu-Oscar-Xray, runway five-right, cleared for takeoff, wind zero-one-zero at eight.” Pérez acknowledged crisply: “Cleared five-right, Zulu-Oscar-Xray.” Radar tracked the aircraft climbing through 900 feet, approximately three miles east of the airport, before the secondary surveillance radar return disappeared at 8:17 a.m. The primary skin-paint echo also faded shortly after. No distress call was received, and the transponder ceased transmitting Mode C altitude. The sudden loss of contact was not immediately alarming, as small aircraft occasionally dropped off secondary radar due to low altitude, terrain masking by the nearby Sierra de Guadalupe, or temporary transponder failure, but standard procedure required confirmation of visual contact or radio check-in within five minutes.
Flight instructor Captain Luis Morales noticed the absence of the aircraft during its expected return window. He had been monitoring the frequency from the school’s operations room—a cramped space with a VHF radio, a coffee-stained desk, and a wall map marked with training corridors. At 8:25 a.m., he stepped outside to scan the horizon with binoculars. The eastern sky was empty. By 8:30 a.m., with no sign of the Cessna and no response to repeated radio calls, he alerted the tower. Controller García initiated the airport’s lost-aircraft protocol. A search was underway involving ground units from the airport fire brigade driving along the lakebed access roads and an aerial patrol by a Bell 206 helicopter from the rescue service. The lakebed area was searched thoroughly, as it was a common site for emergency landings during training; instructors often practiced forced-landing drills there. Teams on foot checked drainage ditches and abandoned shacks. Local residents—mostly farmers and salt harvesters—were questioned, but none reported unusual sights or sounds. The helicopter pilot flew grid patterns up to 20 kilometers east, but fuel constraints limited the search to 45 minutes.
At 9:15 a.m.—58 minutes after the last radar contact—a commercial pilot flying a Mexicana Airlines DC-9 en route from Guadalajara to Acapulco informed Mexico City Approach that a small aircraft was circling overhead and attempting to raise controllers on the local frequency The DC-9 was at flight level 240, and the captain, José Ramírez, provided the Cessna’s approximate position about 10 nautical miles north of Acapulco’s VOR. Acapulco tower, located on a hill overlooking the bay, established contact with the pilot, who identified himself as Rafael Pacheco Pérez, Student #82 from the Mexico City aviation school. Pérez sounded disoriented and repeatedly asked for his position and landing instructions. He reported that his last memory was climbing out of Mexico City, followed by a sudden heaviness in his eyelids, and then “waking up” over water with mountains to his left. Controllers noted that his voice initially carried a normal tone but briefly changed to a lower, flatter register during a 30-second segment of the transmission. In that segment, an unidentified speaker stated in Spanish, with no regional accent detectable: “We are using the pilot only as a microphone. You are not alone in the universe, and there are other races that we are keeping away from you, but we are watching you.”
The transmission ended abruptly with a click, and Pérez’s voice returned to normal. He expressed confusion and fear, stating he had no memory of speaking those words and that the aircraft’s fuel gauge showed nearly full tanks—specifically, the left tank at 6 gallons and the right at 5, totaling 11 gallons. He was instructed to enter a left downwind for runway 28 and was given vectors to final approach. Pérez landed without incident at Acapulco’s General Juan N. Álvarez International Airport at 9:25 a.m. The touchdown was smooth, and he taxied to the general aviation ramp under his 
own power. Aeroméxico maintenance personnel, alerted by the tower, met the aircraft immediately. Lead mechanic Arturo Sánchez drained a sample from each tank sump and confirmed no water or contamination. A dipstick measurement showed 11.2 gallons remaining. The aircraft logbook showed 12.0 gallons at takeoff, verified by the refueler’s signature. No structural damage was found: no dents, no paint transfer, no propeller strikes. The engine ran smoothly during a 5-minute ground test at 1,700 RPM, and all instruments were normal. The elapsed time from engine start to shutdown was 1.2 hours, yet fuel consumption should have been approximately 9 gallons for the distance and time.
Pérez was taken to the airport clinic and then transferred to the IMSS hospital in downtown Acapulco for examination. Blood tests showed no alcohol, barbiturates, amphetamines, or carbon monoxide exposure. A urine screen was negative for common drugs. A chest X-ray and ECG were normal. A physician noted an elevated heart rate of 110 beats per minute and mild dehydration but no injuries or neurological deficits. Psychologically, he appeared shaken and repeated that he remembered only a sudden drowsiness shortly after takeoff—described as “like warm sand in my eyes”—followed by “waking up” over the Pacific coast with the sun higher than expected. He was kept under observation for 48 hours, during which he slept fitfully but showed no signs of delirium. A consulting psychiatrist, Dr. Elena Ortiz, noted in her report: “Patient is oriented ×3, affect anxious but appropriate. No thought disorder. Memory gap of approximately 60 minutes, consistent with dissociative episode or external influence, though no chemical evidence supports the latter.” He was released on June 23 with a recommendation for follow-up in Mexico City.
Mexican aviation authorities classified the incident as a “serious incident” under general civil aeronautical regulations but released minimal public information. A one-paragraph notice appeared in the Diario Oficial on June 25, stating only that a training aircraft had experienced “navigational difficulties” and landed safely in Acapulco. No full transcript of the radio exchange was archived officially, though partial recordings circulated unofficially in the late 1970s through airport employees, amateur radio enthusiasts, and a tabloid journalist who purchased a cassette from a baggage handler for 500 pesos. The official investigation concluded with a finding of “undetermined cause” and recommended enhanced radar coverage over the Texcoco corridor. No disciplinary action was taken against the school or instructors.
Pérez never flew again. His student pilot certificate was not revoked, but the medical clearance was withheld pending psychiatric evaluation. He returned to Mexico City by commercial flight on June 24, accompanied by Captain Morales. In a 1982 interview with the newspaper Excélsior, conducted in a quiet café near his home, he described the event as having “stolen my future.” He had planned to join Aeroméxico as a first officer within two years; instead, he enrolled in a business administration course at the Universidad La Salle and worked in insurance sales in Guadalajara for most of his career. He married in 1985, had two children, and avoided publicity. He consistently maintained that he had no memory of the missing hour and no explanation for the transmission. In rare moments with close friends, he expressed bitterness toward the entities—if that’s what they were—for derailing his life without offering answers. A 28-second audio clip, reportedly sold by an airport employee in Acapulco to a local radio station, matches descriptions of the altered voice; the recording begins with Pérez’s normal plea for help, shifts to the monotone statement, and ends with static. Audio analysts from the National Polytechnic Institute in the 1990s noted a pitch drop of approximately 80 Hertz and a slight compression artifact but could not determine whether it resulted from equipment distortion, vocal cord fatigue, or deliberate modulation. Three controllers in Acapulco and the Mexicana DC-9 captain José Ramírez provided consistent handwritten statements to investigators within 24 hours. Captain Morales and controller Ana Luz García confirmed the timeline from the Mexico City end in separate depositions.
Critics suggest Pérez became lost in ground haze over the lakebed, flew south unintentionally along the Valley of Mexico, and experienced hypoxia or spatial disorientation due to fatigue. However, the distance of over 400 kilometers at an average groundspeed exceeding 350 kilometers per hour was far beyond the Cessna 150’s maximum of 200 kilometers per hour. This, combined with the fuel discrepancy and the absence of intermediate radio contacts on any frequency, make this scenario unlikely. Some investigators proposed that Pérez staged the incident for attention or suffered a fugue state triggered by the stress of his first solo, yet the fuel quantity, radar gap, and lack of preparatory evidence – such as hidden fuel or accomplices – remain unexplained under this theory, and no evidence of premeditation was found in his background or finances. Speculation about compass failure due to local magnetic anomalies near Texcoco or radio interference from military exercises has been raised, but the aircraft’s magnetic compass was tested post-flight and showed normal deviation, and there were no indications of restricted airspace activity. UFO researchers cite the case alongside a broader wave of sightings in central Mexico during 1975 to 1977, including the well-documented Teotihuacán lights and multiple military radar tracks; the message resembles contactee narratives of the era—warnings from benevolent overseers—though Pérez never embraced such interpretations and dismissed them as “fantasy.”
The Pacheco Pérez case is infrequently referenced in English-language UFO literature—appearing briefly in works by Jacques Vallée and J. Allen Hynek—but remains well-known in Mexican paranormal circles. Spanish-language podcasts have dedicated episodes to it and local radio programs in Guerrero state occasionally feature call-in segments with listeners claiming similar “lost time” experiences. The original event file is stored at the National Archives in Mexico City in the aviation incidents section but is not digitized; researchers who have requested access under the transparency law report that the documents are intact, bound in a manila folder, and contain no additional technical analysis beyond the initial two-page report and appended statements.
Rafael Pacheco Pérez reportedly passed away on March 14, 2019, at age 63 from complications of diabetes. His obituary in a Guadalajara newspaper made no mention of the 1976 incident. His family declined interviews, stating through a cousin that he had spoken of the incident only once in the last decade, over coffee with his son: “It happened. I don’t know how. I just want it left alone.” The Cessna XB-ZOX was returned to service within a week, logged another 1,200 hours, and was eventually decommissioned and scrapped in 1994 after a hard landing by another student. No physical evidence beyond the paper trail, radar printouts, and partial recording remains accessible to the public. To this day, the Rafael Pacheco Pérez case baffles researchers.
REFERENCES
Dirección General de Aeronáutica Civil. “Informe Preliminar de Incidente Aéreo INC-76-214: Cessna 150 XB-ZOX.” Mexico City: Secretaría de Comunicaciones y Transportes, 1976.