I’m an airline pilot. Can I deduct my union dues?

Not if you are an employee. But your state might allow it if you itemize. 

W-2 employees cannot deduct job-related expenses on a federal return.  Job-related expenses were eliminated as a federal deduction for W-2 employees by the tax laws that changed for 2018 and beyond.  Your state tax laws might be different in AL, AR, CA, HI, MN, NY or PA.

If you live in a state that lets you deduct job-related expenses, the information will flow from your federal return  to the state return, so enter it in Federal>Deductions and Credits>Employment Expenses>Job-Related Expenses

No, at least not on your federal tax return.  The miscellaneous itemized deduction, which included union dues was suspended by Tax Cuts and Jobs Act (TCJA) beginning with the 2018 tax year.  Some states still allow you to deduct union dues on your state tax return, if you itemize deductions.