I find it interesting that this came up. In reference to FedEx's accident in Tallahassee, FL, the findings determined:
"14. Existing aviation medical certification standards for color vision and use of related screening tests may not ensure detection of color vision deficiencies that can be detrimental to safety; it is possible that in some emergency situations, the speed of color recognition may assume an importance that is not currently reflected in the standards."
"15. One or more of the color vision screening tests currently approved for use in the aviation industry (for example, the Farnsworth Lantern screening test) are not adequate; these tests should be identified and their use discontinued."
"Recommendations: Conduct research to determine the effectiveness of each of the current Federal Aviation Administration-approved color vision test protocols ..."
I wouldn't start the long path of aviation based on taking the Farnsworth Lantern. They'll get rid of it soon and you'll be stuck without a job. My two cents.
Source:
http://www.ntsb.gov/doclib/reports/2004/aar0402.pdf