Final answer:
Commercial jets like the Boeing 777 rely on sophisticated computer systems for flight control, so without them, it is uncertain if they can be flown.
Step-by-step explanation:
The ability of an aircraft to be flown after losing all flight control computers is a complex issue that depends on the design of the aircraft and its systems. For modern jetliners like the Boeing 777, which utilize a fly-by-wire system, the loss of all flight control computers would mean the pilots have no electronic means to control the aircraft's control surfaces, like rudders or ailerons.
Historical cases like the Gimli Glider show that skilled pilots have managed to land a powerless jet. Still, the full capabilities without flight computers are largely untested in large commercial aircraft.
History has shown in instances like the Gimli Glider incident, where a Boeing 767 lost all power and became a "dead stick" situation, experienced pilots can perform exceptional feats.
In this case, Captain Robert Pearson glided the plane without engine power to a safe landing. Consequently, while electric flight may still sustain a glider using non-computerized controls, the intricacies of sizeable commercial jets without computer aids are yet to be fully understood due to the reliance on sophisticated computer systems for control.