Think of it this way: the engine on large widebodies can generate 60 - 70,000 lb. of thrust. If an object were to encounter the exhaust blast at close range, it would be feeling a large fraction of that 60,000 lb. force. It could easily overturn a large truck.
I know of a guy who drove his personal car about 100 yds. behind such an engine - it rolled him over completely, fortunately without injury, but the car was a mess.
