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-- In London a member of a ground crew put explosives aboard.
. -- On Flight 103, a passenger knowingly or unknowingly carried the explosives and perished.
Most experts give high marks to overall airport procedures at Heathrow, where officials have for years contended with the possibility of Irish Republican Army terrorism, and at Frankfurt. Others point out that no airport is completely safe. "Baggage control is pretty good at both Frankfurt and London, but tarmac security remains a weak spot everywhere," says an industry official. "A bomb with a timing device could have been put into the forward baggage hold." According to Pan Am officials, security was tightened after the airline received the FAA advisory, but they refused to say what was done.
Terrorist technology is outpacing the ability of authorities to guarantee security. The powerful plastic explosive Semtex, a gummy substance that is generally rolled into thin sheets, is difficult for both dogs and machines to detect. So are the relatively new "woven plastic" explosives, which resemble swatches of fabric and could conceivably be carried in a shopping bag.
While the acrid smoke still hung over Lockerbie, British Prime Minister Margaret Thatcher visited the scene, as did Prince Andrew, the Duke of York. The sight was extraordinary in the daylight: the cockpit resting near a church cemetery, Christmas presents never to be delivered scattered on the ground, sheep grazing in one field and policemen looking for bodies in the next. "One has never seen or thought to see anything like this," said Thatcher, visibly moved by the horror.
Investigators assumed that some clues to the fate of Flight 103 would be contained within the plane's two flight recorders, both of which were recovered from the wreckage. But on Friday they could find nothing abnormal on the voice tape save for a "faint unquantified noise" an instant before Flight 103 lost contact. They were hoping, however, that within a few days they would have further clues as to whether the Christmas tragedy at Lockerbie carried with it a murderous message of political symbolism.