Angle of attack (and flying upside down)
The wing on a commercial airliner is attached to the fuselage with an angle of about 3° nose up. To lift off an aircraft from the ground, the angle of the wing must be increased in addition, by raising the nose (rotation, of app. 10° - 15°). But even during crouse flight the fuselage is not completely horizontal, but hold to 2-3° nose up, so that at the angle of attack is app. 5 °.
Here I would like to come back to the model flight again, because "every" pilot has tried to fly upside down (or the aerobatics in the "big aviation"). According to the theory of Bernoulli (imagine the nice big "lift" arrows on the wings), an aircraft on the back would crash inevitably and fall down faster than a stone! -reverse lift = force down (lift downward) in addition to the gravity. But everyone knows that this does not happen, …the secret is the angle of attack again (on the back you must push…) and this works well not only with symmetrical profiles!