, you are correct about the "авиа́ции" word but wrong about lyotchik. In russia civil pilots a called "пило́т" (pilót), and military pilots are called "лё́тчик" (lyótchik), it is a military profession not a rank same as pilot not a rank in any military. Word "солда́т" (soldát) means soldier and used same way as in english. Word "моря́к" (moryák) in russian comes from word "море́" (moryé) meaning sea so in general speech it coul be translated as a seaman (even some online translaters do that) or as a sailor, but in military ranks important is the equevalency not the translation, and the equivalent to U.S. rank of seeman would be russian rank of matros, while moryak is general term which could applied to anybody who seves in navy or in a civil fleet.