Engineering Division
Memorandum Report No. MCFEXD-691-15D
28 April 1949
UNCLASSIFIED
estimate the distance, size or speed of such objects, and it would be
easy to fail to recognize them.
Conclusions
It is concluded by the writer that there are sufficient psychological
explanations for the reports of unidentified flying objects to
provide plausible explanations for reports not otherwise explainable.
These errors in identifying real stimuli result chiefly from inability
to estimate speed, distance and size.
Recommendations
The following recommendations are offered:
1. Test the ability of pilots to estimate the course of a small
lighted balloon while doing aerobatics with it at night. It is suggested
that several pilots try to fly pursuit curves and collision courses
on such targets at night and report accurately their sensations. It
would be desirable, but probably impossible, to keep them from knowing
the nature of the light source.
2. In all future reports of unidentified objects specify the
location of the object with reference to polar coordinates (direction
and degrees above the horizon) rather than asking individuals to estimate
distance. If possible, obtain an estimate of size in terms of the
visual angle subtended by the object.
3. In all future investigations determine the angular position
of the sun with respect to the unidentified object and the observer.
Also determine the approximate time during which the object was in
sight (this information was not available for more than half the
reports).
UNCLASSIFIED
14
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DOWNGRADED AT 12 YEAR INTERVALS: NOT AUTOMATICALLY DECLASSIFIED. DOD DIR 5200.10