The question of how a twin-engine widebody like the Boeing 777 maintains controlled flight after losing an engine touches on one of the most rigorously tested and heavily regulated aspects of transport-category aircraft design: engine-out performance and controllability. The short answer to the asymmetric thrust problem is indeed the rudder, but the fuller answer involves a combination of certification requirements, aerodynamic design margins, and crew procedure that together make single-engine flight not just survivable but a routine training and checkride event. Under FAA and EASA certification standards (14 CFR Part 25 and its European equivalent CS-25), every twin-engine transport aircraft must demonstrate adequate directional control following the failure of the critical engine at the most adverse combination of weight, altitude, and speed. This is codified in the concept of VMC (minimum control speed) for smaller aircraft and, for large transport jets like the 777, in takeoff and landing performance calculations that ensure the airplane can maintain a straight flight path using rudder alone, without exceeding a defined bank angle, at any speed above V1 (takeoff decision speed). The 777's rudder, along with its vertical stabilizer, is sized specifically to counter the yawing moment produced by an engine failure at the worst-case scenario: full takeoff thrust on one engine at low speed, aircraft near maximum weight.
The mechanics of countering asymmetric thrust involve more than just stomping on a pedal. When an engine fails, particularly during takeoff or go-around when thrust asymmetry is most extreme, the pilot applies rudder to counteract the yawing moment, and typically a small amount of bank (usually 2-3 degrees) into the operating engine, which uses a component of lift to help offset the sideslip and reduces the rudder deflection needed. This "bank into the good engine" technique is a standard airline training item precisely because pure rudder-only correction can require nearly full deflection during the low-speed, high-thrust phase, and combining bank with rudder distributes the workload aerodynamically rather than relying solely on the tail. As the aircraft accelerates, rudder authority increases with airspeed (dynamic pressure), so less deflection is needed to hold heading, which is why V1, VR, and V2 speeds are all calculated with engine-out controllability in mind. Autothrottle and autopilot systems on modern aircraft like the 777 can also assist by managing thrust and trimming out sustained rudder forces, but during the initial seconds after failure, hand-flown rudder input remains the primary tool, which is why simulator training for engine failures on takeoff (V1 cuts) is one of the most repeated and scrutinized maneuvers in airline recurrent training.
For working pilots, this topic is far from academic. Engine-failure-on-takeoff scenarios are a cornerstone of type-rating and recurrent simulator training precisely because they combine high consequence with relatively low frequency, making them ideal candidates for deliberate practice rather than reliance on line experience. Airline and business jet crews drill V1 cuts, single-engine go-arounds, and single-engine approaches and landings regularly, and manufacturers publish detailed engine-out performance data, including maximum structural crosswind limits and single-engine service ceiling, that dispatchers and crews use for every flight planning cycle involving performance-limited runways. The 777 specifically, as an ETOPS-capable twin, has additional layers of scrutiny around single-engine performance because ETOPS certification requires the aircraft to fly extended distances over water or remote terrain on one engine while maintaining adequate altitude and fuel reserves, which places even greater emphasis on the aerodynamic and structural margins built into the rudder and vertical stabilizer.
More broadly, this question reflects a healthy public curiosity about the engineering redundancy embedded in modern jet transport design, redundancy that has made engine failures, while still serious emergencies, statistically survivable non-events rather than catastrophes. The trend toward twin-engine widebodies replacing three- and four-engine designs (747s and A380s giving way to 777s, 787s, and A350s) has only intensified the engineering and regulatory focus on engine-out performance, since airlines and manufacturers have had to prove, repeatedly and conservatively, that two engines provide sufficient safety margin for long-haul overwater operations. Pilots reading these discussions should recognize them as a reminder that the seemingly simple rudder pedal represents decades of aerodynamic engineering, certification testing, and standardized training built specifically to handle the exact torque and yaw problem the original question raises.