COMMERCIAL HEAVIES: A350-1000 vs BOEING 777X
Comparing the A350-1000 and 777X, the respective high-capacity long-haul twin jets from Airbus and Boeing
Going head to head at the top end of the commercial aircraft market are the Airbus A350- 1000 and Boeing 777X. With A380 production set to end in 2021 and the lack of orders for the 747-8 Intercontinental, these aircraft are now very much the manufacturers’ flagships, the largest-capacity and longest-range passenger airliners they produce. What is the latest with these aircraft? What are their features? How do they stack up against each other?
777X tests, A350-1000 fleet expands
At the time of writing in July 2019, Boeing had just started taxiing tests at Everett of Boeing 777-9 N779XW (c/n 64240), the first of two that will be used for 777-9 flight testing. The 777-9 is the first of the two variants in the 777X family; the other is the 777-8.
In June, N779XW was on the taxiways and runway at Everett for the first time undertaking slow taxiing and braking tests. The tests followed the rollout of the aircraft for company employees in March, a quieter event than initially planned after a public reveal of the aircraft was cancelled in the aftermath of the Ethiopian Airlines 737 MAX disaster and that aircraft’s subsequent grounding.
Boeing told AIR International: “Boeing is conducting a series of ground tests as part of the continued development and testing schedule. These ground tests run the aircraft through specific conditions simulating flight. The purpose is to test and verify aircraft systems and flight controls. The recent taxi test was the first time that the aircraft moved on its own power.
“Teams are focusing on the final systems, propulsion and aircraft-level tests necessary to confirm the safety of the aircraft prior to flight, per our normal development process.”
The 777-9’s first flight is delayed. It was initially planned to fly the aircraft in the first quarter of 2019 ready for a 2020 service entry flight testing and certification. The first flight date then slipped because of the discovery of premature wear in a component in the front compressor of the aircraft’s GE Aviation GE9X turbofan.
Speaking at the UBS Global Industries and Transportation Conference in New York recently, Boeing Chief Financial Officer Greg Smith said: “The long pole in the tent right now is the GE engine. There are some challenges. GE is working through its own testing. We’re having to do some retesting and we’re doing that together.”
Boeing is still maintaining a target of flying the 777-9 this year and delivering the first customer example to the initial operator, Emirates, in 2020 following flight and certification testing. Smith said: “Obviously we’re staying very close to that and we’ll keep you up to date if that changes, but that’s still the current assumption.”
In the wake of the 737 MAX grounding there are Congress and Senate reviews under way into the Federal Aviation Administration’s (FAA) procedures for certifying new commercial aircraft. Any consequences from these reviews therefore could conceivably impact the 777-9’s certification and the eventual service entry date.
As Boeing prepares to fly the 777-9, Airbus’ competing product in this area of the twinaisle widebody market, the A350-1000, is already in service. The A350-1000 started commercial flights on February 24, 2018, on launch customer Qatar Airways’ Doha- London Heathrow route.
At the time of writing in July 2019, 22 A350-1000s had been delivered, comprising nine with Qatar Airways, 12 with Cathay Pacific and one with Etihad. British Airways and Virgin Atlantic will be the next operators. Their first aircraft, BA’s G-XWBA (msn 326) and Virgin’s G-VLUX (msn 274) named Red Velvet, both recently left the Toulouse paint shop. The BA aircraft conducted its first flight on July 2, 2019.
What are the A350-1000’s key features?
The A350-1000 is the larger of the two current A350 family variants, at 73.78m (239ft 5in) in length compared to its sister aircraft, the 66.8m-long (219ft 2in) A350-900, thanks to five more fuselage frames between Door 1 and Door 2 forward of the wing and six more frames between Door 3 and Door 4 aft of the wing. Both A350 variants have the same 64.75m (212ft 4in) wingspan, but the A350- 1000 is slightly taller than its stablemate, at 17.08m (56ft) compared to the A350-900’s 17.05m (55ft 11in) height.
The extra length means an A350-1000 is able to carry 350 to 410 passengers (although 369 seats is the typical two-class layout) compared to the A350-900’s 300–350 seats and 44 LD-3 containers underfloor as revenue cargo, up from 36 in its sister aircraft.
The A350-1000’s standard maximum takeoff weight (MTOW) is 316,000kg (696,661lb), after flight testing (the A350-1000 first flew on November 24, 2016, and was certified by the European Aviation Safety Agency and FAA on November 21, 2017) showed there was enough margin to improve MTOW.
During the recent Paris Air Show, a further MTOW increase to 319,000kg (703,234lb) and a range increase to 8,700 nautical miles (16,100km) was announced, which Airbus says will enable the aircraft to undertake more than 18 hours of non-stop flying with a maximum passenger payload.
In line with Airbus’ policy to introduce various payload/range performance choices via new weight variants for the aircraft after service entry to give customers diff erent options over the missions the aircraft can fly, the company’s Characteristics for Airport Planning document shows nine diff erent weight variants for the A350-1000.
The biggest diff erence between the A350- 1000 and A350-900 is the more powerful Rolls-Royce Trent XWB turbofan. The A350- 1000 is equipped with Trent XWB-97s off ering 97,000lb (431.5kN) take-off thrust compared to the 84,200lb (374.5kN) thrust of the Trent XWB-84 on the A350-900.
Another diff erence is the A350-1000 has a trailing-edge extension of 400mm (15.7in), which increases the larger variant’s wing area by 4% to extend the high-lift devices and ailerons to optimise lift and cruise performance.
There are shared part numbers between the A350-1000 and A350-900 to maximise commonality and assist with spares management and maintenance. However, the A350-1000’s greater length and higher MTOW means there are adaptations. The main landing gear is a six-wheel bogie (the A350-900’s is four-wheel), the nose landing gear had to be reinforced due to heavier towing loads and the flaps are diff erent due to higher aerodynamic loads. The venting system also had to be adapted to cope with the higher fuel quantity: the A350-1000 has a useable fuel capacity of 156,000 litres (41,212 US gal) compared to 138,000 litres (36,456 US gal) on the A350-900.
The A350-1000 features extensive use of advanced materials. Airbus says 53% of the A350-1000 is carbon fibre reinforced plastic (CFRP) composites, including most of the fuselage, the central wingbox and other key parts of the wings, the aircraft’s keel beam and tailcone, fuselage frames, doublers, stringers and doors.
Using composite materials eliminates the typical features of a traditional metallic structure such as fasteners, joints and overlaps, which cuts weight and leads to reduced fuel burn and easier maintenance.
The A350-1000 structure also features 14% titanium (which is used for high-load fuselage frames, engine pylons, landing gear and door surrounds), 19% aluminium and aluminium lithium, 5% steel and 8% other materials.
Up to July 5, 2019, Airbus had A350-1000 orders from Air Carabies (three), Air Lease Corporation (ten), Asiana (nine), British Airways (18), Cathay Pacific (20) Etihad Airways (20), Japan Airlines (13), LATAM (eight), Qatar Airways (42), Starlux (12), an undisclosed operator (one) and Virgin Atlantic Airways (eight).
What are the 777X’s key features?
The Boeing 777X family consists of two variants: the baseline 777-9 and the shorterfuselage 777-8. Key diff erences between these aircraft and the earlier Triple Seven variants are their engines and wings. The GE9X turbofans on the 777-9 and 777-8 have a 134in (3.4m) fan diameter, the largest fan ever developed for a commercial aircraft jet engine.
The 777X’s wings have folding tips that extend and retract to maintain the 777’s gate compatibility and maximise aspect ratio. Boeing’s preference on wing design is to maximise span – it says this creates a more efficient wing – but aircraft with wingspans between 52 and 65m (170ft 6in and 213ft 2in) are classified by International Civil Aviation Organization as Code E aircraft; those with 65-80m (213ft 2in-262ft 4in) wingspans, such as the 747-8 and A380, are in a separate category, Code F.
The 777X’s 235ft 5in (71.7m) wingspan in flight would therefore put the 777Xs into Code F rather than Code E, where the currentproduction Triple Seven models sit with their 212ft 9in (64.8m) wingspans, precluding 777Xs from using the same gates as today’s aircraft.
Boeing’s solution was to design 7ft-long (2.1m) folding wingtips for the 777X. On the ground, with these outboard sections in an upright position, the 777X will have the same 212ft 9in (64.8m) wingspan as the current 777s, which will maintain Code E compatibility.
Crews will extend and retract the wingtips using a control panel on the flight deck, the pilots extending the tips for flight and retracting them after landing to make the jet Code E-compliant again. The folding wingtip mechanism (FWT) Boeing has designed involves the flight crew manually initiating the command for the FWT to extend and lock to the take-off position prior to the hold-short line next to the take-off runway.
Boeing documentation says the different geometry of each airport means it would not be practical to automate the extension of the FWT. It says the FWT will automatically fold the wingtips after the aircraft has touched down and ground speed is below 50kts (92km/h). The 235ft 5in (71.7m) wingspan of the 777X in flight, although wider than the 777-300ER’s 212ft 9in (64.8m), is not as wide as the A380’s 79.7m (261ft 8in) wingspan and is far shorter than the huge 385ft (117m) span of the single Stratolaunch aircraft flown early in 2019, by some margin the widest wingspan of any commercial aircraft currently flying.
However, at 251ft 9in (76.72m) in length, the 777X is the longest twin-jet airliner ever developed. It is not only 7ft (2.1m) longer than the 777-300ER (thanks to four extra fuselage frames), but also slightly longer than the 250ft 2in-long (76.2m) 747-8 and 13ft 2in (4m) longer than the 72.7m-long (238ft 7in) A380. The 777-9 is the first twin-engine airliner designed to carry more than 400 passengers.
According to Boeing, the jet will have capacity for 414 seats in a standard two-class seat layout, up from the 777-300ER’s 396 twoclass. Scalloped frames have widened the cabin by 2in (50mm) on either side of the fuselage compared to the 777-300ER, which Boeing says will allow ten-abreast seating in a 3-4-3 layout.
The jet will be able to carry 46 LD-3s (26 in the forward hold and 20 in the rear hold), up from 44 LD-3s on the 777-300ER. According to Boeing’s Aircraft Characteristics for Airport Planning document the 777-9’s basic MTOW will be 775,000lb (351,534kg), the same as the 777-300ER. The 777-9 will have 7,525 nautical miles (13,490km) range.
At 251ft 9in (76.72m) in length, the 777-8 variant will be nearly 23ft (7m) shorter than the 777-9. It will have fewer seats than its sister aircraft (365 passengers two-class), but it will be able to fly further, with 8,690 nautical miles (16,090km) range.
As with previous widebody aircraft families, including the older Triple Seven variants, the 777-9 and 777-8 are designed to be complementary, with the 777-9 providing capacity and the 777-8 providing range and capabilities for specialist missions such as hot/ high-altitude, long-range/hot and long-range/ high-payload.
Just like the A350-1000, the 777X makes extensive use of CFRP. Indeed, at 105ft (32m) long, the 777X’s wing spar is the largest single-piece composite part ever developed for an airliner. A purpose-built Composite Wing Center (CWC) at Everett manufactures four CFRP spars and four panels for the 777X, with Boeing Fabrication in St Louis, Missouri, supplying CFRP leading and trailing edges, ribs and folding tips for the wings, which are transported to the CWC to join the spars and panels.
As of July 5, 2019, Boeing had secured 344 orders for the 777X variants consisting of orders from All Nippon Airways (20 aircraft), BA (18), Cathay Pacific (21), Emirates (150), Etihad Airways (25), Lufthansa (20), Qatar Airways (60), Singapore Airlines (20) and unidentified customers (ten).
How do the big twins compare?
As the figures from the manufacturers show the 777-9 is larger than the A350-1000, with a longer fuselage and a wider wingspan. The fan diameter on the Boeing’s GE9Xs is larger than the Trent XWB-97’s and the GE9X provides higher take-off thrust.
It is however aircraft operating economics that really matter to airlines, and the contest between the manufacturers is naturally closely fought, as each company seeks to portray its product in the best light.
The 777-9’s larger size means its 414 seats two-class capacity exceeds the 410-seat maximum for the A350-1000. This of course directly impacts upon one way of looking at economics: per-seat operating costs. With the Triple Seven’s operating cost divided up between more seats, its per-seat costs will inevitably look better. Boeing claims the 777-9 will be 12% more fuel efficient per seat than the A350-1000.
Despite the extensive use of carbon fibre in its huge wing, the 777X is more traditional in its construction than the A350. The fuselage and central wingbox is made of aluminium. The A350-1000 contains a comparatively higher share of CFRP and other advanced materials, which reduces weight. There is a more than 77,000lb (35,000kg) diff erence in ramp weight between the 777X and A350- 1000, and Airbus claims the wings, folding devices and what it calls “super-heavy and costly engines” mean this will make its competitor aircraft’s total maintenance cost 37% higher.
Airbus told AIR International a higher MTOW no longer reflects a more capable, larger or efficient aircraft. The company said: “The 777-9 is a mix-and-match of old technology, new aerostructures and actuators, old early ‘90s metallic fuselage, super heavy engines, etc.”
Using a somewhat unpleasant expression, Airbus added: “In short, this is lipstick to an old lady; an old lady that is obviously limited in her physical movements as she lacks 1,000 nautical miles [1,852km] of flyable range to compete with the A350-1000. This can also translate into 10 tonnes of additional cargo available on the A350-1000 for long-range missions, hence greater airline revenue.” Airbus also claims on a mission of 6,000 nautical miles (11,112km) range, and using the same payload, “an A350-1000 takes-off 45 tonnes lighter than a 777-9…[and] burns ten fewer tonnes of fuel for the mission”.
The company added: “A350-1000 standard MTOW is 44 tonnes lower than 777-9 and its cash operating cost is 16% lower than 777-9, mostly coming from the fuel burn that is 13% lower on the Airbus …Fundamentally, [the] A350 XWB is a new, highly performing, very reliable and comfortable product. The A350- 1000 is a wonderful platform today, and surely will off er further development potential, while the 777-9 is a final and compromised 777.”
Airbus’ strategic view is that a cleansheet design is particularly important in this market area. It said: “Mixing ‘new’ and ‘old’ design features does not actually work, as subsequently required compromises systematically spiral the overall result out of economic interest. For instance, using larger engines may reduce engine-specific fuel burn, but [it] will surely increase the aircraft weight [and] friction drag, and have [a] snowball eff ect on the wings’ structure, centre wingbox structure, etc.
Boeing disagrees of course, saying the 777X will be 10% cheaper to operate than an A350-1000. It also claims its aircraft will generate 12% less carbon dioxide emissions and be 20% more fuel efficient than its European competitor.
According to an analysis by Leeham News and Analysis, long-established analysts of the commercial aviation industry, the 777- 9’s higher seat count gives the aircraft an advantage. Although the A350-1000 off ers a superior operating empty weight, the consultancy says the GE9X being designed slightly later than the Trent XWB-97 gives the 777-9 a 3% lower cost seat/mile cost which, it says, “is valid for long flights”.
Change the metrics and the numbers come out slightly diff erently. Leeham says if seat/mile costs are based on an average sector length of around 3,000 nautical miles (5,556km) the A350-1000’s lower weight narrows the 777-9’s advantage to 2%. The consultancy says: “With the seat/ mile costs at similar load factors within 3% and the aircraft/mile cost of the smaller A350-1000 9.6% better, [it] is a question of the capacity needs of the airline on its route structure,” as to whether an airline picks the A350-1000 or 777-9.
Ultimately, as the CAPA Centre for Aviation consultancy has pointed out, the contest between commercial aircraft – and judgement on which aircraft is ‘better’ – rests with each individual airline’s specific capacity, payload and range requirements. With those requirements inevitably varying between carriers, the 777X will probably be more suited to certain markets and the A350-1000 to others.
CAPA says: “Airlines consider [the 777X-9] to be a better fit for premium, large markets. Compared to the A350-1000, the 777-9 is viewed by airlines to have more range and to be able to carry more passengers (and cargo) at the right cost.
“The A350-1000 falls short on payload for trunk routes and/or those that are ultra-long, [but] airlines foresee a role for the A350-1000 on large volume markets that are not quite as premium as blue-chip ones, and markets that are long haul but do not need the full range of the 777X.”
After the 777-9 is introduced Boeing will work on flying the 777-8 shorter fuselage/ longer-range variant. The company has always said it plans to introduce this variant around 18 months after the 777-9, which based on the current development timeline suggests a service entry date well into 2022 at the earliest.
Of the 777X family’s total 344 orders as of July 2019, however, only 53 (eight jets for Etihad, 35 for Emirates and ten for Qatar Airways) were for the 777-8. As noted in the market overview section of this feature on the heavies, there are only so many requirements for very long range airliners.
Boeing is committed to the 777-8, but speaking at the UBS Global Industrials and Transportation Conference, Chief Financial Officer Greg Smith said Boeing was monitoring, “the demand for 777-8 and see if that still makes sense. And do we want to push that [development timeline] out?”
Alternatively, having an ultra-long-range platform in the product mix might just be ideal. In its Project Sunrise initiative, Qantas Airways has challenged the manufacturers to produce an ultra-long-range high-capacity airliner that is able to fly non-stop from Australia’s east coast to Europe or the eastern seaboard of the United States: routes long seen as a blue riband for commercial aircraft, an ultimate test of an airliner’s capability and onboard comfort.
Qantas is involved in discussions with both Airbus and Boeing about what they could do to meet its requirement. The airline, which already flies the longest-duration nonstop service with its Perth–Heathrow service operated with Boeing 787-9s, wants to introduce aircraft capable of flying Melbourne–London, Melbourne–New York, Sydney–London and Sydney–New York nonstops in around 2022.
Speaking at an Amazon event in Sydney in June 2019, Qantas Chief Executive Officer Alan Joyce was quoted as saying there has been a huge reaction in the manufacturers to the challenge. Joyce commented: “Airbus said it was a bit like the space race, the race to the moon; that’s how they’re treating it in their organisation.”
The Project Sunrise challenge means further evolution of the Airbus and Boeing big twins looks highly probable. For Boeing, responding to the challenge suggests using the longer-haul 777-8, while it is notable how Airbus has recently again updated the A350- 1000’s capability by introducing a further weight variant increasing MTOW and range.
Any future long-range A350-1000 subvariant would probably draw from Airbus’ experience modifying the A350-900 to produce the A350-900ULR (Ultra-Long- Range) subvariant, of which Singapore Airlines operates seven for nonstop ultra-long-haul flights from Singapore to New York JFK.
Separately, Airbus has already explored stretching the A350-1000 to create a new A350 family variant, dubbed the A350-2000 by analysts and media in recent years (and also variously referred to as the A350-1100 or A350-8000), that would more closely match the 777-9’s 414-seat capacity.
Meanwhile, Boeing said in 2016 a stretched 777X variant dubbed the 777-10, seating up to 450 passengers, is technically feasible should customers want it.
An A350-2000 or 777-10 are clearly longerterm possibilities. Boeing is obviously focused on 777-9 testing, certification and service entry and Airbus in 2017 put the A350-2000 on the backburner as it feared cannibalising sales of the A350-1000 (and the A380, at that time then still off ered to the market).
This situation doesn’t mean things will not change in the next few years, however, especially as a challenge like Project Sunrise off ers a stimulus for developing new capabilities.
More broadly, and although it seems odd to regard new twin-engine widebodies so recently introduced to service as ‘ageing’, by the middle of the 2020s airframe and engine technologies on these aircraft will be between one and two decades old.
With a new generation of turbofan engines such as the Rolls-Royce UltraFan set to emerge during the next decade, it is entirely plausible there will be more developments of the big jets, whether that involves the manufacturers adding new members to the product families or adding further capabilities to existing aircraft. AI