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This section provides definitions of the twenty "types" of anomalous sighting reports, indicated by two letters and a number, presenting them in a two-dimensional matrix comprising four groups with five categories within each group. Once a "type" is determined and affixed to a report, it provides for others a quickly understood indicator of the proximity and behavior of a phenomenal event, as well as its level of interaction with the witness(es) and the physical environment. Field Investigators are encouraged to learn and use this readily memorable classification system.

Vallee has proposed four groups with five categories in each group that form a neat, two-dimensional structure (see diagram). The CE group will be mostly familiar, as it has developed from Hynek's famous three categories: Close Encounters of the First, Second and Third Kinds, with a fourth category added to describe the abduction phenomenon and a fifth to denote wounds, scarring, healing or death. For distant flying objects (following Hynek's definition of 500 feet, 150 meters, or more), Vallee suggests classifying them according to the apparent behavior of the object rather than circumstances independent of it, such as daylight or night, into two groups: MA for "maneuvers" and FB for "flyby." The genius of this scheme is in the introduction of the AN group for "anomaly," which allows the classification of the full range and variety of phenomena with which we must deal, such as flashes of light illuminating the sky, detonations or shock-waves from no known source, misplaced masses of earth, persons relocated large distances in a short space of time, sounds, images or artifacts specifically associated with the flying saucer phenomenon in the minds of the reporters (with the agreement of the MUFON investigators) in situations where no flying object was actually seen.

Following are the formal definitions. Field Investigators, analysts, researchers and interested readers of this manual should come to know the definitions and use them in their personal work and communication with others. Let MUFON headquarters know if you find cases clearly within the realm of flying saucer phenomena that cannot be classified within one or more of these "types."


AN1 are anomalies that do not have lasting physical effects, such as amorphous lights or unexplained explosions.

AN2 are anomalies with lasting physical effects, such as some poltergeist phenomena, apports (materialized objects), and areas of flattened grass.

AN3 are anomalies with associated entities. This class could include reports of ghosts, yetis, and other instances of cryptozoology as well as elves and spirits.

AN4 are those anomalous reports in which witnesses experience personal interaction with entities in the reality of the entities themselves. They include near-death experiences, religious miracles and visions, and many cases of out-of-body experiences.

AN5 are cases of anomalous injuries or deaths, such as spontaneous combustion or unexplained wounds or even permanent healing,

FB1 is a simple sighting of a UFO "flying by" in the sky, the category most frequently reported.

FB2 is a flyby accompanied by physical evidence.

FB3 is a flyby of an object accompanied by the observation of beings on board.

FB4 is a flyby where the witness experienced a transformation of his or her reality into the reality of the object or its occupants.

FB5 would be a flyby as a result of which the witnesses would suffer permanent injuries or deaths.

MA1 gathers those UFO observations that involve an object with a discontinuous trajectory (such as a drop, a maneuver, or a loop).

MA2 includes those cases that give rise to physical effects in addition to a discontinuous trajectory.

MA3 contains the cases of objects with discontinuous trajectories when beings are observed on board.

MA4 covers instances of maneuvers accompanied by a sense of transformation of reality for the percipient.

MA5 is a maneuver as a result of which the witnesses suffer permanent injury or death.

CE1 is the class of objects seen on the ground or at a short distance to the observer.

CE2 is the class of close encounters in which physical effects or traces were present.

CE3 is the class of close encounters that involve "entities" or "occupants".

CE4 encompasses the abduction reports in which the witness has not only seen the occupants but claims to have extensively interacted with them inside their craft.

CE5 encompasses cases of Close Encounters in which the witnesses have suffered permanent injuries or other physiological effects, including death.

(from Vallee, Jacques, Confrontations, New York: Ballantine, 1990)