> Eventually the costs become too great to ignore, and companies must upgrade their systems. But that is the moment of maximum danger, for the new software must

> Eventually the costs become too great to ignore, and companies must upgrade their systems. But that is the moment of maximum danger, for the new software must do everything that the half-understood old one does, and more. It is, to repeat a common but apposite analogy, like rebuilding an aircraft in flight. I've always felt this analogy is wrong on many levels. I'm guessing most attempts at rebuilding an aircraft in flight would result in failure and death. While many of the rewrites I've heard if failed, few resulted in the death of a company. Not all rewrites come with the same risks and there are strategies to deal with the risks, such as the so called strangler strategy from Martin Fowler. I feel like discipline, organization, proper budgeting and organizational resolve are strong predictors of success with rewrites. I couldn't say the same for rebuilding an aircraft in flight.