The MC-130 transport that crashed on take off in Afghanistan in June was overloaded. This was the conclusion of an investigation of the accident. Two pilots and a Special Forces medic died in the crash, while seven other passengers survived. The MC-130 is a modified C-130 used by Special Forces and commandos. The aircraft can fly in any weather and be refueled in the air. But tactical transports like this have to be careful what they carry and where they store it. It's easy to overload a C-130, because of it's large, square cargo space. The loadmaster not only has to keep the weight low enough so the aircraft can safely take off, but also make sure that the weight is distributed properly to keep the center of gravity where the pilot expects it to be. Put too much weight in the wrong place, and the pilot can lose control once the aircraft is off the ground. Another danger, particularly in a place like Afghanistan, is heat and altitude. When an aircraft is taking off from a "hot and high" airfield, not as much weight can be carried (because the wings don't lift as much weight in hotter and thinner air). Often the pilots can work around improper loading. But if too many things go wrong at once, the aircraft crashes.