Pakistan, June 17 -- US Air Force B-52 Stratofortress bomber crashed on takeoff on Monday at Edwards Air Force Base in Southern California's Mojave Desert, bursting into flames and killing all eight crew members aboard, Air Force officials said. The eight-engine, jet-powered aircraft, built to carry a wide array of nuclear and conventional bombs, was on a routine test mission when it crashed on the runway at Edwards just after leaving the ground, Air Force Colonel James Hayes said at a press conference hours later. A towering pall of black smoke billowing from the crash site was visible for miles immediately after the accident. He said the "mixed crew" aboard the aircraft consisted of government civilians, government contractors and unifo...