Dr Fox, Hansard 13.7.11
"Dr Fox: In fairness, the board of inquiry said that the most likely cause of the crash was pilot error, but it did not attribute blame. The air marshals used their experience and intuition to make a judgment based on the board of inquiry’s findings. Lord Philip and his team found that they were not able to do that based on the level of evidence required to attribute negligence in the way that they did."
This is a good summary of a sad tragedy.