The plane is airborne because of lift. Lift doesn't account for upward acceleration.
Yes, it does. In general, there are four forces acting on a plane:
- Lift (up): generated mostly by the wings. The fuselage and engine can contribute a small amount to this depending on the shape of the plane and the angle of attack.
- Weight (down): generated by gravity (or Universal Acceleration, if you are a flat-earther)
- Thrust (forward): generated by the engines.
- Drag (backward): generated by air resistance.
For straight and level flight, these four forces must be balanced. Lift=Weight, Thrust=Drag.
If Lift is greater than weight, the plane accelerates upward. If Lift is less than weight, it accelerates downward. If Thrust is greater than drag, then the plane accelerates forward. If Thrust is less than drag, the plane slows down.
In fact, angle of attack accounts for upward, downward or level flight in a plane.
Yes, changing the angle of attack can change the amount of lift generated by the wings, causing the plane to accelerate up or down. Lift is approximately proportional to the angle of attack.
Either way the plane has to be moving forward for lift to work and even forward movement isn't enough to guarantee proper lift if the angle of attack is wrong.
Yes, the wings only generate lift if the plane is moving forward. Lift is approximately proportional to the speed of the plane squared.
Since you've narrowed the difference between Bob and the plane down to wings being the deciding factor, if a plane stops all forward motion why does it fall from the sky? If the angle of attack is incorrect why does it fall from the sky?
Yes, wings aren't the only deciding factor. Bob would also need to be able to generate some thrust, either with an engine or by flapping really hard. I thought this was rather obvious, sorry.
It seems to me that this magical force which is accelerating the plane upward with the earth would be able to act upon anything within its sphere of influence, at least in some fashion. Why will a plane, complete with wings but without forward momentum, fall from the sky if this magical, accelerating force is acting upon it?
There is nothing magical about lift, although it can be pretty complicated when you get into the nitty gritty details.
I guess you were under the assumption that I thought wings by themselves were enough to generate lift. Obviously, the plane must be moving forward at a sufficient speed and have the correct angle of attack for the wings to actually generate lift.
The plane has sufficient airspeed to allow the wings to generate lift. Bob doesn't have wings (for lift) or an engine (for thrust to maintain airspeed to generate lift). Hence, Bob falls when he steps off the plane.