Yes, it's cleared to take off with three and fly with two engines.
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Two of the 90-115 also have more takeoff thrust (~230k lbf) than the original 747-100 (~175-205k lbf). So, in theory, two modern engines can power a 747, but only the original, not the 747-8. Twins have higher thrust requirements, as they have to be able to take off with just one engine, while quads can use three.
The 747 is certified to fly on just three engines, and there was no indication of any damage to the aircraft's other engines. Safety experts and aviation regulators still questioned the decision to operate such a long flight with one engine out.
In theory, having multiple engines should increase safety. If one engine fails, the other can help get you safely back to the ground. But don't let this fool you. Engine failure in a multi-engine airplane can lead to complex situations that require advanced pilot skills.
Built in 1967 to produce the mammoth jet, it remains the world's largest manufacturing plant according to Boeing. But after five decades, customer demand for the 747 eroded as Boeing and Airbus (AIR.PA) developed more fuel efficient two-engine widebody planes.
The Boeing 747-400 experiences the least degradation in performance, making it safer during an engine failure. Fitting an aircraft with four engines also increases power, enabling more passengers, heavier payloads, and increased performance.
One of the unique features of the 747 was its fifth pod. This 'spare' engine mount gave it the ability to lug along an extra engine, something it was capable of doing even on a revenue flight. Of course, the efficiency of the flight would take a hit, but reportedly there were no issues with handling as a result.
For example, with a glide ratio of 15:1, a Boeing 747-200 can glide for 150 kilometres (93 mi; 81 nmi) from a cruising altitude of 10,000 metres (33,000 ft).
Boeing 777-9Boeing's 777-9 is the world's largest and longest twin-engine commercial aircraft. Once it goes into service, the 251-foot-long aircraft will ferry up to 425 passengers on long-haul flights—spanning up to 7,285 nautical miles—around the world.
Boeing 777-9Boeing's 777-9 is the world's largest and longest twin-engine commercial aircraft. Once it goes into service, the 251-foot-long aircraft will ferry up to 425 passengers on long-haul flights—spanning up to 7,285 nautical miles—around the world.
Efficiency. The primary reason why Boeing opted for a twin-engine 777 was due to the unparalleled efficiency it offers. Boeing had already noted the use of the 767 on transatlantic operations after ETOPS certification in 1985, bringing down the last barrier for long-haul twinjet operations.
While the Boeing 747 carries more passengers and has a longer range, the 777X surpasses it in cargo capacity and fuel efficiency. The cost of operating the 777X is lower than the 747 due to newer technologies and larger engines, making it a better long-term investment for airlines.
From the mid-1990s, twin-engine aircraft such as the Boeing 777 and Airbus A330 offered the same payload, the same range and lower operating cost than the triples, and that was the end of the road for the triple-engine giants as passenger aircraft.
The planes are due for delivery in 2024 as part of a $3.9 billion contract. Boeing's 777X, its latest passenger plane model and projected replacement for the 747, is set for delivery in 2025.
The Airbus A380 beats the Boeing 747 in passenger capacity, with the ability to accommodate 250 more passengers in a full economy configuration. The A380 offers more interior space, allowing for the inclusion of bars, showers, lounges, and private suites, making it a popular choice for luxurious first-class offerings.