Or you could just change how the salary is calculated, 100% of the higher salary + 50% of the lower salary, instead of 75% of each. That way you won't have lower paying job skills dragging down the salary of pilots, navigators and engineers.
Raising the Gunner's base salary to 2500 Cr takes care of the problem, at 2000 Cr the dual skilled Pilot/Gunner would make the same as a Pilot-2, so 2500 Cr. Of course this means the Gunner makes more than the Medic so the Medic's salary goes up, and the Steward's too.
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These adjustments result in the following salaries for combined skill crew members:
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