I would say that for interviews its worth covering them - ask your girlfriend/wife/sister/mother for info. A heavy concealer or stage make up could probably cover them for an interview.
Once you have the job, then I wouldn't even mention it, and if the subject comes up you can say you had them when you were employed. Of course, you must check the company regs in case its strictly forbidden. In general I think for pilots it not really a problem although our cabin crew have to cover any tattoos when working.