pilot and copilot
until
PAN AM...they made it captain and first officer in deference to nautical terms as there planes were seaplanes (not all).
And it took off. In my manual covering a famous , large manufacturer known for doing a lot of work in washington state, the book says pilot and copilot.
so, don't worry about it.
I did see a dictionary definition once of copilot: a fully qualified pilot ACTING as second in command.