>what would happen if one engine were at 0% and another 100%
Planes are designed to fly fine in that situation - it's what you get if one engine breaks down. Now landing the thing with one engine stuck on 100% would be interesting. I guess you could kill the engine somehow - turn off the fuel or pull the fuses.
Indeed, planes are not designed to be flown in that configuration normally, but they are certainly capable of single-engine flight in emergency situations (where the alternative would be "flying like a ton of bricks"). Exhibit A: http://en.wikipedia.org/wiki/British_Airways_Flight_9
No, actually "capable of flying" means capable of performing all flight maneuvers required for safe flight and landing, including takeoff, go-around and approach/landing.
BA Flight 9 failed all four engines, normally not survivable - but managed to restart all four engines by windmilling. So they recovered in time for landing.
Just curious, where did you find that definition of "capable of flying"? Because under that definition a glider ( unless it is a motorize glider ) is not "capable of flying".
Okay, under that definition, you are correct. Note that the flight later lost engine #2 again (incidentally making the record of five engine failures on a single flight), so it landed with 3 engines operational.
Planes are designed to fly fine in that situation - it's what you get if one engine breaks down. Now landing the thing with one engine stuck on 100% would be interesting. I guess you could kill the engine somehow - turn off the fuel or pull the fuses.