Terrible day.
A few thoughts.
The BBC and CNN keep on about the amount of organisation required by the scum, but surely only a dozen or so were needed - 2 per a/c plus one at each airport to smuggle arms on board.
My experiences of US security lead my to believe that whilst passenger gate security is good, apron security is poor. I retired less than a year ago, but I had learnt enough about Boston security to avoid it if I chose.
Did the Pittsburg crew realise what was happening and make the ultimate sacrifice?