A Boeing 727 has disappeared from Angola. Was it insurance fraud? Has a cartel of diamond smugglers got it? Or could it be in the hands of al-Qaeda? William Langley reports. The old Boeing had done its duty well. It had served 26 loyal years in the colours of American Airlines, but its best days were long gone, and as the sun rose over West Africa on May 25 this year it sat forlornly on the greasy concrete apron of Luanda International Airport in Angola, apparently leased to Air Angola. It hadn't flown for 14 months, and its sorry state...