ow significant is the risk (likelihood of occurrence times how bad it is when it occurs)
How effective is any given mitigation strategy at reducing the risk?
How much does the mitigation strategy cost? Not only in raw dollars, but also in terms of other risks it introduces?
There are basically two types of risk
Demonstrated Risk / This is where accidents or incidences are occurring and that safety hole needs to be plugged
Perceived Risk / where there is as yet or insignificant demonstrated risk but where the authorities feel there could be a threat.
Perceived risk was shown in the Volcanic ash eruption.No aircraft had ever been brought down by ash in the history of aviation although a few were close but huge chunks of airspace were closed with inaccurate ash flow charts
Bird strikes had demonstrated risk but large chunks of airspace were not closed in the migration season.
in this case there is an element of both demonstrated on the fact that this tragic crash has happened but also perceived as the general public in the same way they did in the ash drama need reassurance! In this case that a mad pilot isn't in the front of their aircraft alone free to do his worst
for me the biggest issue in this dreadful crash was the door that door system has now been shown to be a demonstrated risk but in the opposite way that it was intended and the the reason it was originally fitted that way! as with all demonstrated risk that risk needs to be reduced so no ability to lock a flight crew member out of the flight deck! how you do that ??
No one has mentioned how that poor Captain must have felt realising that he had been duped, what was going on and the fact that he could do nothing about it because a locked door stood between him and saving the aircraft and its passengers