> When dealing with a large project, whether it is a new plane, a big infrastructure, anything large and unique, you should take any budget with a big pinch of

> When dealing with a large project, whether it is a new plane, a big infrastructure, anything large and unique, you should take any budget with a big pinch of salt, there is no way anyone can predict precisely how a complex project, that involves a lot of research, millions of moving pieces, is going to cost from the outset. You are talking about uncertainty -- e.g. risk. But that should lead you to overestimate as often as you underestimate so that you're average is on target but there is wide variation in individual results. If there is a systemic bias causing you to underestimate costs consistently, then you cannot blame uncertainty for that.