Having a problem towing a car on a trailer?

Crossing the straps is an aircraft thing. In the Air Force we had to secure the load to a certain G-Force in any direction. There is an actual formula used to determine the capacity of the tie down device in any direction. If the tie down devices (chains or straps) are straight from to back, then under the formula they are giving you no lateral security for the load (even though they really are). So the tie down devices need to be at an angle. The person who mentioned crossing the straps was talking about on a helicopter. Since a vehicle may be nearly as wide as the helicopter, crossing the tie downs was likely the only way to get enough lateral support for the load. I was on a large cargo plane in the air force, so we rarely had to cross the tie downs because our tie down points were normally far wider than the vehicle being secured.