APRO Bulletin, Vol. 24 No. 2 (Aug 1975)
On May 2, 1974, Carlos Antonio de los Santos Montiel, 23, left Mexico
City in his Piper Aztec 24, registered as XB-XAU, for Zihuatenajo,
state of Guerrero. He arrived there in the afternoon and although he
had originally planned to return that day, he decided to stay over and
return on the 3rd. He had dinner at 8 p.m. and retired.
The morning of the third was cloudy with considerable smog, mist and
very poor visibility. Carlos took off, nevertheless, at 10:30, without
having his breakfast. He climbed his little plane to 13,500 feet but
conditions were still bad so he climbed to 14,500 where he found a
clear blue sky and continued on his return trip to Mexico City.
Arriving in the area of Tequesquitengo, Carlos decided to lose altitude
in order to make visual contact with Lake Tequesquitengo and verify his
position, instead of depending on his instruments. When he got down
underneath the cloud cover, ground mist and fog blocked his view of the
Lake. Then things began to happen.
When he looked from the left (he had been gazing through his left side
window) to the front he became aware of something on his right and
glanced in that direction and was shocked to see an object with the
appearance of two plates joined together at the rim with a cupola which
had what seemed to be a little window and an antenna on top. It was
positioned 20 centimeters above the surface of the wing and about 1 1/2
meters from the Piper's cabin. (See drawing by Staff Artist Robert
Gonzales.) A glance back to the left revealed another object of the
same description in the same position above the left wing.
"I was petrified," Carlos told officials later, "after I saw a third
object which seemed about to collide head-on with the windshield. But
it went beneath the aircraft and I heard a strange noise from below as
though it had collided with the underside of the plane."
Carlos then noted that his airspeed had decreased from 140 nautical
miles per hour to 120. He tried to bank to the left, in an attempt to
"bump" the object away from his plane but the controls were frozen and
would not move. He then tried to let down the landing gear, hoping to
get rid of the object under him, but with no results.
APRO's Field Investigator, Fernando J. Tellez Pareja, listened to the
tape-recorded conversation between Santos and the Mexico City
International Airport Control Tower, which Carlos initiated after he
found his controls were frozen:
Carlos: Center Mexico from extra bravo extra alfa union. Mayday!
Mayday! (Ed. Note: "Mayday!" is an international distress signal.)
Mexico City: Come in, extra bravo extra alfa union. (Here the pilot
repeated his call twice — apparently he did not hear Mexico City
answer.) Center Mexico here, come in extra alfa union.
Carlos: Extra alfa union to Center Mexico. My aircraft is out of
control — I have no control over it — I have three unidentified objects
flying around me. I have three unidentified objects flying around me,
one came under my aircraft and hit it. The landing gear is locked in
and the controls won't release them. My position — I am on the Radial
004 from the VOR Tequesquitengo — I am not controlling the plane —
Center Mexico, can you hear me?
Center Mexico: Take note extra alfa union, give me your position and
your situation. We are contacting competent authorities and (here
interrupted by Carlos again)
Carlos: The aircraft is out of control.
At this point, Mexico City International Airport closed its runways to
traffic and prepared for the expected emergency landing. The objects
continued maintaining position on XB-XAU, exerting complete control
over the aircraft.
The "Mayday" or emergency call was received at 12:15 p.m. on Saturday,
May 3. The control tower contacted Ignacio Silva la Mora (Carlo's
uncle), an authority on aircraft, who was put in touch with Carlos via
radio to analyze the problem and help with landing preparations.
When Carlos had reached the Ajusco navigational fix, the UFOs had
elevated the aircraft from 15,000 feet (the altitude while over
Tequesquitengo) to 15,800 and then, one by one, they left. First the
object over his left wing elevated until it was over the cabin, then
above the object on the right wing, and then these two flew off and
were lost to view in the direction of the Popocatepetl and
Iztaccihuatal volcanoes. The controls of the aircraft were immediately
normal and Carlos regained control.
Carlos then attempted to lower the landing gear, circling Mexico City
International Airport eight times, in radio contact to ascertain if he
was successful. Finally, after 40 minutes of circling while he worked
on the control column with a screw driver, he managed to lower the
wheels and landed at 1:34 p.m. on the grassy area between runway 5
right and 5 left where emergency vehicles, including firemen and
ambulance, were waiting.
After landing, Carlos was taken to the Airport Clinic where he was
thoroughly examined and found to be normal and fit. Some individuals
had hinted that he might have been under the influence of drugs or
alcohol but the medical examination laid that speculation to rest.
Two days after the incident, Captain Augusto Ramirez Altamirano (Chief
of Inspectors for the region from the Aeronautical Civil Direction)
said that Carlos would have to undergo a series of tests to determine
if he had really seen the UFOs or if they were an illusion from flying
too high without oxygen.
On May 7, Dr. Luis Amezcua, Chief of the Aviation Medicine Department
of Mexico City International Airport, completed a series of medical
tests (neurological, physical and psychiatric, etc.) and gave his
opinion that Carlos had been suffering from low blood sugar because he
had not eaten from 8 p.m. the night before until after the incident the
next day and inferred that Carlos had hallucinated.
Field Investigator Telles interviewed the witness and gives us the
following insight: Carlos de los Santos is 23, has been a pilot for two
years, has 370 flying hours to his credit, has a private and commercial
pilot's license. He is employed by Pelletier, S. A., a company which
specializes in analysis and study of water. His father is Chief
Mechanic of the Mexicana de Aviacion Airlines. Carlos neither smokes
nor drinks, is not interested in science fiction and has never read a
As far as radar confirmation was concerned, Mr. Julio Cesar Interian
Diaz, the Mexico City International Airport Terminal Radar Controller,
said that the distance from Tequesquitengo to Mexico City is 48
nautical miles and that the blip of Carlos' plane was picked up on
radar when 43 miles out of Mexico City. Carlos' aircraft was the only
one in that sector at that time. The radar registered the separation of
another blip which went in another direction from Carlos' plane,
executing a 270-degree turn in a radius of 3 or 4 miles at a speed of
450-500 nautical miles per hour. Mr. Interian Diaz said that he did not
know of any aircraft which could execute such a maneuver.
Further in-depth investigation is being conducted by an aeronautical
engineer with the help of Field Investigator Fernando Telles. We should
note here that this is Mr. Telles' first important case and he has done
an outstanding job of investigating and reporting.
(Editor's Note: Regarding the theorizing concerning the low blood sugar
reaction: Carlos exhibits none of the symptoms of hypoglycemia (low
blood sugar): sluggishness, irritability, overweight. Had he actually
been a diagnosed hypoglycemic and suffered such a fearful
hallucination, the fear would have triggered a release of adrenalin
into his blood which would have, in turn, triggered a high flow of
insulin, resulting in shock, in which case he would not have been able
to land the airplane.)