[b_davis_]

that mismatch between risk / requirements and the type of contract is the root of this whole problem.

if it was cost plus, the government would have had an incentive to no push for changes, since they would have been paying for it.

and yes, Boeing should have said no. but, politics.

[jjk166]

Requirement changes on cost plus contracts are endemic. And it's not one way - typically the pipeline is starting to work on the project with requirement A under the assumption it will cost X, find out a decent way through that it's going to cost way more than X, then change to requirements B under the assumption it will only cost Y, repeat two or three times.