Mwashi..
It would appear that Lockerbie meant nothing to the USA security system.
I flew from Atlanta to orlando about a year ago. I arived early, checked my baggage and was then informed that I could go on an earlier flight.
When I commented that my bag had already been checked for the later flight I was told that it would automatically go onto the first available flight - and if I went on the one I was scheduled to get, the bag would be in Orlando waiting for me when I got there.
When I quizzed the staff about unacompanied baggage the response was "You must be from either Europe or Saudi Arabia - you guys care about that sort of stuff".
They went on to explain that they really do not see it as a threat and that the majority of flights has unacommpanied baggage on board.