A visitor to Boeing’s web site this week will be in for a shock: the listed seat-counts and range specifications for nearly all of the company’s models have changed, some dramatically.

But Boeing officials say not to be alarmed. The underlying aircraft performance is no different. Boeing has simply updated a set of generic weight and configuration assumptions used to calculate aircraft range.

“There’s no performance change to the actual airplane. Our airplane is doing just fine, and the customers won’t see any change to their rules. This is just changing our generic philosophy to more closely represent what our customers are using,” says Jim Haas, a Boeing marketing director.

As the first such update since the early 1990s, some of the changes appear significant. For example the predicted range for six models – 737 Max 7,737 Max 200, 787-9, 787-10, 777-9X and 777-8X – each decline by more than 500nm. Two other types, the 787-8 and the 777-300ER, lost almost 500nm of listed range.

By changing the assumptions now, Boeing finally acknowledges what most airline customers, industry analysts and rivals already knew. The standard set of assumptions Boeing has used to calculate performance for generic marketing purposes has been “obsolete” for a long time, Haas says.

“The reason we kept it so long is we look at the actual seat counts [the marketing brochures] were showing they were pretty representative of the actual seats airlines were putting in airplanes,” Haas says.

Although the numbers may have been similar, the weight of the passengers, their bags and the seats themselves have been growing substantially. At the same time, the first class cabin used in earlier assumptions has all but disappeared, replaced by more elaborate business class cabins with lie-flat seats and premium economy cabins.

As a result, there has been a growing mismatch between the numbers that Boeing presents in marketing presentations and the numbers that they show to airlines in closed-door sales discussions.

“We really wanted a set of generic ground rules that better reflected what airplanes used in operation,” says Randy Tinseth, vice-president of marketing.

Most airlines provide fleet performance data on their web sites, but the listed figures usually parrot Boeing’s marketing information. An exception to that rule is Lufthansa, which lists range figures for each aircraft in its fleet using the airline’s own ground rules. Lufthansa’s passenger-carrying fleet is mostly filled with Airbus models, but it does include a revealing snapshot of the 747-8 Intercontinental.

Boeing previously listed the latest version of the venerable 747 series with a 467-passenger cabin and a range of 7,790nm. But Boeing’s updated internal assumptions reduced the cabin to 410 passengers and a range of 7,730nm.

That moves Boeing’s assumptions closer to the specifications listed on Lufthansa’s web site, but there is still a wide gap between them. Lufthansa lists the 747-8I with a 364-seat cabin and a range of 7,073nm.

ModelSeats, 2-class (new)Seats, 3-class (new)Seats (old)Range (new)Range (old)
737 Max 7126N/A1263,350nm3,850nm
737 Max 8162N/A1623,515nm3,660nm
737 Max 9178N/A1803,515nm3,630nm
737 Max 200200N/AN/A2,700nm3,345nm

Source: Cirium Dashboard