I would imagine they meant that in a relative way
By "nothing unusual", the accident investigators may have meant only that they heard nothing that they wouldn't expect in any other crash of this sort. That may sound callous, that they call the flight crew's crys for help nothing unusual, but some of that is expected. They are looking for something far more unexpected to be considered unusual.
~~~)-Steven----
"I want you to remember that no bastard ever won a war by dying for his country.
He won it by making the other poor dumb bastard die for his country..."
General George S. Patton