This reminded me to ask about a similar question: I am currently interviewing. Assuming I get an in-person interview, that will involve a long flight. I feel like I shouldn't tell my current employer that I'm interviewing until I have an offer, but in order to hide it I presumably will have to take holiday on fairly short notice, have a plausible reason for why I'm taking it, and generally act like I'm not taking a long flight to an interview. There's a chance that I'll have to do this multiple times. (Though ideally I'd take multiple in-person interviews in the same trip.)
I don't particularly like the idea of doing this. It feels deceitful and stressful. How bad an idea would it be to just let my employer know what's going on?
It depends a lot on your company, so I think your inside view will be better than our outside view. I told my employer when I went out to do a tryout with CFAR, and that went well. One reason I told my boss was that, if I were hired, I'd need to scramble to get all my projects annotated well enough to be able to pass of seamlessly, and I didn't want her to be left in the lurch or to make any plans that hinged on having her quant around for the next month. (Hiring sometimes took a while at my old company).
My boss really appreciated my being forthright and it saved me a lot of tsuris. I think it also worked better because it was expected that people in my role (Research Associate) wouldn't stick around forever.
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.