The Farnsworth Lantern Test, or FALANT, is a color-blind test, originally developed to identify signal lights at night. The test shows pairs of vertically oriented lights (red, green, yellow). It screens for red-green deficiencies, but not the much rarer blue color deficiency. Many feel it is more realistic measurement of color vision ability correlating with piloting aircraft and watercraft. Some may find they pass the FALANT at a higher rate than other traditional color vision tests. Accepted as an approved color vision test for the FFA medical examination, the Farnsworth Lantern is a good alternative for those with inconsistent results with color vision testing.  It is important to stay updated with the latest approved color vision tests available found here:

https://www.faa.gov/ame_guide/app_process/exam_tech/item52/et

As the Farnsworth Lantern Test is one of the original color vision tests, the unit has become harder to find. At Mt Hood Eye Care, Gresham, Oregon, we have a working model and have aided many pilots with their color vision testing for their FAA medical examination.