When I worked at Bell-Northern Research (and Nortel) they had two tracks for advancement. One was the managerial track where you were promoted from a technical staff to a manager, the other was the independent technical adviser. If you did the latter, you basically became a manager without any staff and you worked with the managers at your level to direct the products. There weren't many in my division, but there were some. I was unofficially one because my department manager left (after the rest of the members left) so I reported directly to the manager the next level up and sat in on the department managers' meetings.