Exactly. Tho' once underway if the pilot wants to put saving fuel as a priority he can lower the CI and stay in ECON-or got to LRC etc. Some airlines put a lot of resources (cost accountants) into calculating CI for sepcific routes, times of day etc. And that repays itself handsomely. Others use rules of thumb. On all the figures I've seen the better the level of analysis of variable and non-variable costs, the better the CI and the better the result.