[naves]

Because there is not up or down for the wing when its cutting through a fluid. It is not that we have seen planes flying intercontinental flights upside down.

And those upside down events do not happen at 10 feet above ground. There is plenty of fluid (air) above and below the aircraft and power (fighters jet engines are the most powerful ones on aircrafts) to be able to correct any up-downward force with flaps (basically walls to air)

[marvin]

This is nonsensical. Glider pilots (no engine!) fly aerobatics programs all the time, in planes with curved wings. If the pilot is a bit of a masochist, they could fly upside down for half an hour in still air given enough altitude. The various forms of air resistance will be greater and energy/altitude loss hence higher, but the wing will still be generating lift equal to the weight of the airplane.

[boublepop]

> Because there is not up or down for the wing when its cutting through a fluid.

Except that there obviously is. Unless you ignore gravity.