The concurrency is a major reason for massive cost overruns. If you're building production aircraft before the testing and evaluation phase is done with protot

The concurrency is a major reason for massive cost overruns. If you're building production aircraft before the testing and evaluation phase is done with prototypes, every time you find a major issue you have to retrofit dozens or even hundreds of planes. But, like a lot of things with the JSF program, concurrency made it much more difficult to cancel. Sunk costs and all that.