I feel like I've outgrown my current job and want to make a diagonal move into a different sector of my industry. I'm actively looking for jobs and interviewing.
I'm currently a single-point failure on a major project (through no fault of my own) and I both like and respect the project manager. At what point should I disclose to them that I am actively interviewing and likely to leave the company in a short timeframe? This person has no ability to influence my stay/go decision by making a counter-offer, but I don't want to burn any bridges.