Too much weight?
Only a factor on takeoff, after 9 hours of flying, the plane is light.
Debbie Wilkes (an eyewitness): I was traveling along (Highway) 401. Approaching west end of runway, watching storm unfold, moving very slowly, saw a fork of lightening strike down and hit something; there was a thick billowing smoke. We then noticed what had been hit was a plane. People pulling over to the side of the highway -- 2 or 3 cars. Pouring rain. People running out of their cars, assuming trying to get over the fence to help. Those on the slow lane trying to pull over and help. I did not see any flames engulf the airplane; I only saw smoke."
5:27PM ET