Initial assessments of an airline crash are commonly made by professionals and experienced pilots. However it's important to note that their analysis is similar to making a jigsaw puzzle with only a few pieces. An attempt is made to make the larger picture with limited info.

As the real investigation starts, these pieces start to increase. Investigators may find that engines had not flamed out at impact and were spooling normally? Then they will turn their attention to why the cockpit communication indicated that the crew had lost their engines

The FDR will be examined to verify the condition of the engines at impact. This is just an example of how these inquiries work. Slowly and over time the investigators have enough of the jigsaw pieces to assemble a picture which could be totally different than the initial

Assesment. There is nothing unusual in this process. Early assesments are made with very limited preliminary information and data and quite often the final picture could emerge to be very different.