Accounts were found to follow a similar sequence of events: A witness or witnesses would be in an isolated rural area and come across a crashed aerial vehicle. Stopping to investigate, they'd see, from a distance, strange-looking "beings" who were apparent passengers of the vehicle. Soon thereafter, a military convoy with soldiers would arrive and order the civilian witness[es] to leave the area and not tell anyone what they saw. The military personnel would then commence with their recovery of the vehicle and its occupants.
Specific details of the "beings" also had common threads: Several witnesses described thinking the "beings" were "plastic dolls" or "dummies." Other common features were that the "beings" had four fingers or lacked a small finger. They were "hairless" or "bald." Their garb was "one-piece suits... shiny silverfish-gray color."
Additionally, witnesses were often vague about the date of the occurrence, saying "around 1950" or "I don't recall the date." And, similar vehicles were described being present: "wrecker," "six-by-six," and "medium-sized jeep/truck" and "weapons carrier." (pp. 13--14)
The Air Force identified these common elements and attempted to find: events which from a distant appeared unusual; events with no precise date; events occurring in rural New Mexico; events involving vehicles and dummies with four fingers and one-piece suits; events utilizing numerous military personnel and vehicles including wreckers, six-by-sixes, weapons carriers, etc.
Searching records of the near-by bases and researching the vehicles and programs under development and their attendant activities quickly eliminated many candidates as sources for these events based on dissimilar activities or geographic location. Programs involving missiles, drones and aircraft research were thus eliminated.
When it came to high altitude balloon tests, however, similar properties were identified. While on many projects there was no material which could reasonably be mistaken for an alien, several projects did use equipment which could be mistaken for aliens: anthropomorphic dummies. These dummies were used in New Mexico starting in May 1950 and their use was not widely publicized initially. Today, these sorts of dummies are widely recognized, especially when used for crash tests. To the eyes of a civilian witness in the 1950s, a high-altitude balloon recovery with attendant dummies would have seemed very unusual. (p. 17)
The Air Force explored the programs using these dummies and found two which fit the witness descriptions in many respects. The programs High Dive and Excelsior used dummies to test methods of returning pilots or astronauts to earth via parachute from great altitudes. Dropped from heights as great as 98,000 feet, 43 high altitude balloons carrying 67 dummies between June 1954 and February 1959 and were recovered throughout New Mexico as the balloons tended to drift. An additional 30 dummies were dropped by aircraft by White Sands Proving Grounds in 1953, and 150 were dropped by aircraft over Wright-Patterson AFB in Ohio in 1959, a location of other "alien" sightings. It was observed that a number of the recovery locations matched locations from where claims of alien recoveries emerged. (pp. 23--24)
To counter claims of a "cover-up," the report notes that these tests were not secret and were widely publicized by the mid-1950s. Articles in high-circulation publications such as Life and National Geographic appeared, as well as television shows and even a feature film. "On the Threshold of Space" was released in 1956 and features actual anthropomorphic dummies.