In the decade through 2002, armed robbers staged at least 10 major heists on the tarmacs of European airports, and robbers who didn't pull guns executed many more thefts of cash, diamonds and other valuable cargo from high-security areas, according to airport-security specialists.

WSJ: Gunmen Waylay Jet, Swipe Diamond Trove

People handling airfreight are aware of valuable consignments because every cargo shipment carries a waybill, which is similar to a passenger's boarding pass.

WSJ: Gunmen Waylay Jet, Swipe Diamond Trove

The San Pedro's cargo was far more valuable.

BBC: Wreck diving in Bermuda