From Outbound Air –

“Right then, if your teams can carry on the same way tomorrow, then what do I need you for?” Catherine stared sternly in the eyes of her executive team.

Peter looked around to see if someone else might fill the void of silence. It was Mary’s turn. “You are absolutely right. My team can carry on the same way, day after day. And they can make decisions and they can solve problems, as long as those decisions and problems are the same as yesterday. But, here’s the rub. Something is going to change. It might be a weather system, a mechanical delay, or a broken flight connection. Something is going to change and that’s when they will need me.”

“Exactly,” Catherine beamed. “As long as nothing changes, your teams do not need you. They can handle all the routine decisions and problems. But, you know that something will change, something always changes.
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Back to the central question, how do we define the word -manager? What is the role of a manager?