Wilful neglect would surely lead to criminal proceedings but that isn't the answer here.
The accident has been dissected by both the AAIB and the Sheriff Principal yet no reason can be found for the breakdown in CRM and basic piloting in this case.
Is is a Human Factors issue? Almost certainly but all the usual suspects have been looked at so what is the answer?
The word negligent is hardly subjective as the different dictionary definitions show.
I stand by my original post of negligence (not wilful or intentional) because for whatever reason they failed to do what they were supposed to do despite training, checks and a great deal of experience (especially rom the commander).
Was the commander the issue? Was it a personality clash? Was it too much deference to experience?
If people don't tell the truth then we won't know - pretending they weren't negligent and that there is a mysterious and as yet unknown human factor at work is the decision of the really closed mind.