Sorry that I'm late to the discussion, it seems that some great posts have already been made!
My organization has succession management plans as well, although I don't personally handle them. As such, I can't comment too closely on how we do it. (a disadvantage of working in a training related agency; although I work in HR, I don't actually work in _our_ HR. It gets confusing)
I found Matthew's situation to be interesting, in that managing expectations has to be a key part of succession planning. Obviously, the teachers who had quit either found that their new training gave them better opportunities elsewhere, or it is also possible that, given a taste of the more managerial position, they weren't interested in the job.
For this reason I would think that one of the first steps before bringing anyone on-board for a succession management development program should be a thorough screening of career goals and motivations, as well as honest discussion of realistic expectations and possibilities. Many people who have participated in a training program or are aware that they are being groomed to take over a leadership post can develop an over-inflated view of their abilities, and as such may be quick to head elsewhere if they see better opportunities. In many cases this may be a result of not realizing that knowledge and training are not replacements for actual experience, which can only come with practice.
Jackie's point about having to take the easy way out and contact a recruiter is, I think, very common in many organizations. The most likely reason, to me, is that most organizations are treating succession planning as a very formal procedure, and even if an internal training system is being implemented the participants are specifically being identified to fill specific roles.
- For example: Bob gets hit by a bus; Steve is Bob's designated replacement. If Steve is not ready, then the company has to call a recruiter. Steve, meanwhile, realizes that the new hire will likely stay for several years, which limits his chances of advancement until then, so begins to look for a new job. (or hopes the new guy gets hit by a bus as well)
Had the organization been conducting succession planning more flexibly, building up bench strength as Jackie had mentioned, then they could have had 3 or four candidates available for Bob's position, or at least a few who would have been suitable for sharing some of Bob's duties until they had developed the experience to handle it alone. The organization could treat succession management not as a straight-line chart, but rather as a method of developing a pool of candidates ready to assume new responsibilities. Ensuring that participants were aware that the company was actively developing them, even when new positions were not yet available, would decrease their likelihood of leaving if they were overlooked for an opportunity. This would also keep them actively working on their leadership skills, which would benefit the organization as a whole. In this fashion a clear, well designed succession plan could ensure a suitable pool of talent, increase organizational capability and employee engagement, and decrease turnover as well as recruitment costs.
For that all to work top management needs to be involved and plenty of feedback and support needs to be given, not just the HR department or even individual line managers. It's a complex task, but I think it's rewarding even for small or mid-sized organizations.