Second Officer, name, title or functions vary with different airlines.
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Generally, if a crew of 3 pilots, it will be the most junior pilot. The order will be (1) Captain, (2) First Officer. (3) Second Officer. There is no official definition for the title... nor an assigned number of stripes on uniforms.
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Might be 5 stripes and two stars...
The higher the title, and number of stripes, the lower the salary...
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Happy contrails