Chris Seymour, Flight Ascend Consultancy's head of market analysis, considers the issues around a new twin-aisle family to serve the MoM

Debate about the middle of the market (MoM) has gained traction in recent months, having been a topic of discussion for several years. Some in the industry have begun to label the new small twin-aisle design as the Boeing 797X.

From a timing perspective, both Boeing and Airbus are looking to the 2020s and considering what to do next, as their current development programmes conclude and enter service by 2022. Boeing said late in 2016 that it is evaluating a programme to develop an MoM product for entry into service in 2024 or 2025.

The interest stems from a market where single-aisle seating capacities and range capabilities are increasing and there is a perceived need to have aircraft with capacity in the 757 to 767 size but without the very long ranges that most current twin-aisle types are offering.

The key questions that need to be answered are: where actually is the MoM segment; what is the potential demand and is it large enough to justify the investment in a new design; and what type of aircraft could serve this market, at what price and with what operating economics?

Other considerations include the technologies available to enable improvements in performance, economics, pricing and especially development costs – a vital issue given Boeing's performance with 787 development spending. Plus, what will be the competitive responses from Airbus and other manufacturers?

At the ISTAT Americas conference in San Diego back in March, several lessors and US airlines – including Delta and United – discussed proposals for a family of small twin-aisle aircraft of 225 to 260 seats in dual class and with a range of 4,800nm (8,900km) to 5,200nm. This would place it between the 4,000nm range of the highest-weight 757 and the 5,590nm capability of a high-weight 767-300ER.

The engine power range would likely be around 40,000lb-thrust (180kN). The proposed aicraft is seen as an ideal replacement for current fleets of 757 and 767s, of which the three largest US majors still operate some 420 between them. Of course it will have to be designed as a global aircraft and not just for North American requirements.

In July 2016, Boeing forecast a total market of 4,000-5,000 aircraft for an MoM-sized aircraft but with the Airbus A321neo and A330neo taking a portion of this, leaving a demand for some 2,000-3,000 units.

Will it appeal to low-cost carriers, which are moving into longer-range missions? Is it a good aircraft for intra-China and intra-Asia, as well as Middle East to Europe?

Will the new type be used for increasing frequency on routes currently served by larger 300-seaters or used to upgrade from current single-aisles. Is it a route fragmenter, opening new routes between secondary cities?

Seats and range of single-aisle and small twin-ais

Searching for a gap in the market, Flight Ascend Consultancy has estimated and plotted typical dual-class payload ranges in the above chart, for selected single-aisle and small twin-aisle types.

Capacity and range of the in-production single-aisles is certainly increasing. The A321neo will be able to carry up to 240 passengers in a high-density layout with the Airbus Cabin Flex and a new door configuration from the second quarter of 2018, while the A321neoLR version will increase range to 4,000nm by using a 97t MTOW and a third auxiliary centre tank. Aer Lingus is the latest airline to choose this version for transatlantic service, joining Norwegian, TAP and others as customers. Norwegian is starting Max 8 transatlantic flights this summer.

Boeing is responding with its Max 10X proposal, a fifth member of the family which is a further 66in (1.67m) stretch beyond the Max 9. This will enable a capacity of up to 230 seats, with Boeing claiming 5% lower operating trip and seat-mile costs than an A321neo. Entry into service would be around 2020 if launched. But there is a danger of cannibalisation between the Max 8, 9 and 10, and the 10 cannot fully match the A321neo capacity. Even Boeing said last year that neither the Max nor A321neo was the answer to the MoM.

One of the key questions is how much range to build into an MoM design. Comparison of the average flight distances against the maximum possible range on current twin-aisles shows that only around 40-50% of that range is required to meet the average – most operations never require the full range capability built into the design.

What is the current data on flights actually telling us about size and range requirements?

Analysis from Flightglobal schedules data for July 2017 shows that the average twin-aisle has 304 seats and the average flight distance is around 2,570nm. By contrast, the average single-aisle has 164 seats and 718nm flight distance.

Twin-aisle flights by range

As can be seen in the chart above, the most twin-aisle flights being operated per week are actually on routes below 1,000nm – some 28%, although these only generate 6% of the available seat-miles. At the other end of the scale, the ultra-long range-flights of over 7,000nm represent just 1% of both flights and ASMs.

About 90% of twin-aisle flights, generating 75% of ASMs, are on routes under 5,000nm, which is the core of the MoM proposals. Some airlines are being creative in using their twin-aisles, for example flying an A330-200 from China to Europe one day and on shorter flights within China the next – so flexibility is key.

Analysing only twin-aisle aircraft with configurations of below 260 seats, these have an average of 234 seats and 2,670nm flight distance, with 60% of ASMs below 4,000nm and 82% below 5,000nm. If considering only the A330-200 and 767, the most popular small twin-aisles in operation, the figures are even higher at 66% and 92%, with the longest current route at 6,000nm.

So an MoM design with a range of 4,800nm-5,200nm looks to be in the right area to cover the vast majority of current operations with current and previous generation small twins, as well as providing increased range above where single-aisles operate. The 757s currently have an average of 1,580nm flight distance, with the longest routes at 3,400nm.

A key question is what engines will power the aircraft, and will there be a choice? The improvements in wing technology and aerodynamic efficiency are reducing the thrust requirements in newer generation aircraft, so these are expected to be in the 40,000-45,000lb-thrust area. Boeing's head of marketing Randy Tinseth indicated in 2016 that he expected a step change from the engine manufacturers.

Available options are expected to include the Rolls-Royce Advance or Ultrafan, a geared fan from Pratt & Whitney and an engine from CFM, General Electric;s joint venture with Safran. Recent launches (A350, A330neo and 777X) have had no engine choice so the trend to a sole-source supplier may continue.

Technology will be key to driving efficiency and lowering operating cost. Boeing has already heavily invested in composite capability for the 787 and 777X wing and technologies developed on the 787 will be mature by the time of a 797X launch. This should all help to limit development costs, which are likely at least to be in the $10-15 billion range.

Pricing of the new aircraft will also be crucial to its market appeal. It will lie somewhere between larger single-aisles in the $50 millions and the A330neo and 787-8 in the $100-120 millions (all these figures are Flight Ascend Consultancy's base full-life opinion for a new aircraft today). The 767-300ER in its heyday was in the $70 millions. At such prices, could an MoM generate sufficient sales to recover the non-recurring development cost and deliver profit for the OEM?

A seven-year development programme would be consistent with the 777X timescales, leading to entry into service in 2025.

If Boeing launches the new aircraft, which is looking increasingly likely, what may be the competitive response? Airbus has been quite vocal to date about the A321neo being their solution. It could counter by improving the wing design of the A321neo (an A322neo?) and lower operating costs further. However, this cannot address all the capacity and range offered by a smaller twin-aisle.

Boeing said earlier in March that it was continuing to study what an MoM aircraft could look like: "We're having very productive conversations with our customers and firming up opportunities there."

So the market awaits what may be the next new product launch.