Boeing had announced that its 777X does not feature a Manoeuvring Characteristics Augmentation System (MCAS), like the one used on the 737 MAX series. Here’s why and what makes the two aircraft fundamentally different.
The Boeing 777X is the latest generation of the manufacturer’s best selling 777 series, which first flew back in 1994. However, the B777X’s entry into service is already behind schedule, following several technical problems.
Structurally, the 777X builds upon the proven design of the original 777. However, it features updated technology, new GE9X engines, and a whole new wing with folding wingtips so that the plane can fit in all current airport gates.
As a whole, the 777X does not have the same amount of modification between the older and recently updated variants. But there was a drastic change between the older 737 variants to the MAX ones.
Why was MCAS Introduced on the 737 MAX?
The MCAS system was developed for the 737 MAX series, citing the considerable modification to the previous 737 aircraft, combined with a strong desire to retain the original certification and only change the looks of the older design. But the 777X does not have similar modifications.
The 737 MAX uses the same fuselage, landing gear, same wing with a new set of winglets and aerodynamics, same tail fin and stabilisers and many other similar features, but larger and heavier engines. Moreover, the engines are mounted farther forward on the wing compared to previous 737 variants.
Rather than redesign the aircraft completely or mandate full simulator training for pilots transitioning from older 737 models, Boeing introduced MCAS as a software-based solution to ensure the MAX “felt” similar to previous 737s. This decision allowed Boeing to market the MAX as requiring only minimal pilot retraining — a key selling point for many airlines.
However, the flaws in this system was found to be the leading cause behind the two deadly crashes that killed 346 people on board, leading to a global grounding of the 737 MAX fleet in March 2019. Since then, Boeing updated the system with improvements and restored the aircraft to service.
Why the 777X Doesn’t Require MCAS?
Unlike the 737, the 777 which was initially designed back in the 90s has always been a fly-by-wire aircraft and has full-time fly-by-wire flight controls, with computers involved in each control input. This means that the task MCAS was meant to apply to the 737 MAX is already built in the 777 aeroplanes as a part of its initial control rules.
Moreover, the 777X maintains a similar engine placement and balance to earlier 777 models. There’s a minor difference in the design of the aircraft and the location of the engine is not even changed
The Boeing 777X has much longer landing gear with plenty of clearance between the wingtips and the engine to fit the new large engines well under the modified wing. This clearance gap pulls the aeroplane in a standard, neutral manner, which does not require additional electromechanical support like the MCAS to make it feel usual to the pilots.
Therefore, having no drastic differences between the latest Boeing 777X and initial 777s, there is no need to create an artificial feel through software like the 737 MAX.
What’s Next for the 777X?
As of early 2025, the Boeing 777X program remains in the final stages of certification, with the first delivery now expected to take place in 2026, following years of delays. Originally slated for entry into service in 2020, the program has faced multiple setbacks, including issues with the GE9X engines, fuselage pressurization testing failures, and more stringent certification requirements following the 737 MAX crisis.
Lufthansa is set to be the launch customer of the Boeing 777-9 variant. Moreover, Emirates, the largest operator of the 777 family, has remained committed to the aircraft but has expressed frustration over delays, even converting some orders to smaller models like the 787. Other major customers include Qatar Airways, Lufthansa, ANA, and Singapore Airlines.
The 777X directly competes with the Airbus A350-1000, which seats about 360 passengers. Both aircraft competed for head to head to win orders from Qantas for its Project Sunrise flights. Eventually, Qantas opted for the Airbus A350 over the 777X, citing delays in the programme.
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