Challenger blew up because engineers, giving a warning based on a known defect for the specific conditions of that specific launch, were ignored in that case.
On Military aircraft, in the UK, we deal with that by inserting a Limitation in the RTS, as ours is a Limitation Based Release process. In the case of Challenger, some would say the “limitation” was so restrictive that it was actually a Constraint (again, I use the UK term). If something (in this case a seal or gasket) has a temp spec that is incompatible with conditions one experiences at launch or during flight, then to me that is a design defect that MUST be rectified before approval to fly in ANY conditions. It is indicative of major problems in your design and approval process and a bit of a clue something bad will happen.
This is exactly what happened on a number of the accidents discussed here. The causes or contributory factors, on Nimrod, Chinook, Sea King ASaC, Tornado/Patriot, Hercules and others were predictable, predicted and notified by engineers; and, as you say, ignored. The most damning part is they were ignored by other engineers (and those who pretended to be engineers). Just as you describe on Challenger.
But as Chug has pointed out, Haddon-Cave actively protected those who ignored the above. Much of his report is good stuff – primarily the bits he simply copies from evidence submitted to him but lets the reader infer he uncovered it all himself. But much of his analysis and opinion is very flawed and he proved himself untrustworthy and sycophantic. And then he got his gong.
Good points above about COTS. No, RJ cannot in any way be described as a COTS procurement. And, while ACM Bollom may have been mentioned in the press release, perhaps one should look a little lower and ask if there is any (a) staff and (b) procedural failure commonality between Nimrod and RJ. Neither bothered much about airworthiness, ignoring advice and instructions and abandoning it to try to save time and money. Maybe one day we’ll see the audit report that spells all this out, and perhaps the MAA will come forth with the truth about what action they took, instead of the sanitised version we’re getting now – again, protecting those responsible. That report makes it clear all the RJ problems were known years ago.