In this analysis I will compare the Boeing (NYSE:BA) 777-9X that will enter service in 2020 with the Airbus (OTCPK:OTCPK:EADSF/OTCPK:OTCPK:EADSY) A350-1000. It has to be noted though that this is not the most logical comparison to make since the Boeing 777-9X is bigger, but since Airbus made this comparison to show how 'light weight' their Airbus A350-100 is I will go ahead and make this comparison as well.

In the second part of this small study I will compare the Boeing 777-8X with the Airbus A350-1000.

The Boeing 777X is the successor of the Boeing 777 and features:

- Wing made out of CFRP which reduced the weight of the wing component
- Slightly wider cabin, which allows for wider seats in dense configuration
- Bigger wings that increase aerodynamic efficiency by
**12%**compared to the Boeing 777-300ER - New GE9X engines will be
**6-8%**more efficient than the engines on the Boeing 777-300ER

During Airbus' investors days last year Airbus showed the following chart:

*Figure 1: Comparison between the Airbus A350-1000 and the Boeing 777-9X (Source:* *airbus.com**)*

Airbus made the comparison between the A350-1000 and 777-9X to show they have the lighter air frame. Another reason is because the A350-1000 and Boeing 777-9X have similar range capability. Below I will outline why the comparison between an Airbus A350-1000 and Boeing 777-9X is not a reasonable one to make, I will do so by going ahead and make the comparison anyways. This will show that Airbus merely made the comparison to compare weights, rather than efficiencies.

It has to be noted that the figures used for the SFC are making the difference in the comparisons. Rolls Royce is not clearly specifying the SFC advantage the Trent XWB has. For now I calculated a value close to **0.49 lb/lbf/hr.** GE claimed the GE9X engine one the Boeing 777X to be 8% more efficient, which gives a figure similar to that of the Trent XWB engines. At the same time GE claims their engine will be 5% more efficient than any competing engines in 2020. For now I will be using the 8% figure provided for the calculations, which might be seen as a conservative estimate.

Using the numbers available gives the following results:

*Figure 2: Comparison general characteristics Boeing 777-9X and Airbus A350-1000 (Source: Dhierin-Perkash Bechai)*

Looking at the general characteristics it becomes immediately clear that Airbus is comparing a far larger aircraft with the Airbus A350-1000. The Boeing 777-9X has a higher weight, due to the fact that is has a far higher capacity and therefore needs a heavier structure. The Boeing 777-9X has better aerodynamics and seems to be having similar propulsive efficiency.

For a 4000 nautical mile trip this yields the following results:

*Figure 3: Results for a 4000 nm trip for Boeing 777-9X compared to the Airbus A350-1000 (Source: Dhierin-Perkash Bechai)*

The figure shows that profit is mainly driven by the increased capacity. Fuel costs per seat-mile are **$0.040** for the Airbus A350-1000 and **$0.039** for the Boeing 777-9X.

*Figure 4: Advantage of the Airbus A350-1000 as presented by Airbus (Source:* *airbus.com**)*

As can be seen Airbus claims 15% lower costs per trip and 5% lower costs per seat, but does this by comparing a bigger aircraft in 3-class configuration, with an aircraft in 2-class configuration.

The total operating costs might indeed be 15% better, my analysis showed a 16% higher fuel burn for the Boeing 777-9X. Translating this to a per seat figure the fuel costs per seat are marginally lower for the Boeing 777-9X.

Comparing both aircraft on a wider range shows that differences are minimal:

*Figure 5: Comparing the Boeing 777-9X and Airbus A350-1000 on a wider range (Source: Dhierin-Perkash Bechai)*

Figure 5 quite clearly shows differences are small, but that the Boeing 777-9X has the advantage (even when using a conservative estimate on the specific fuel consumption of the aircraft).

As I pointed out earlier it is not quite clear how much fuel the Trent XWB engines consume, therefore estimated a value that came pretty close to the SFC of the GE9X engine.

Using the claim that the GE90X engine will be 5% more efficient, which is not weird to assume since the engine is slightly bigger (for every inch that is added in fan size the fuel consumption drops by 0.5%) the figure change a bit:

*Figure 6: Comparing the Boeing 777-9X and Airbus A350-1000 on a wider range (Source: Dhierin-Perkash Bechai)*

For a 4000 nm trip this translates to:

*Figure 7: Results for a 4000 nm trip for Boeing 777-9X compared to the Airbus A350-1000 (Source: Dhierin-Perkash Bechai)*

In terms of fuel costs per nautical seat-mile this translates to: **$0.042** for the Airbus A350-1000 and **$0.040** for the Boeing 777-9X.

So in both comparisons the Boeing 777-9X ends up on top. I think that the second analysis, assuming a higher fuel consumption for the Trent XWB, is more credible. This quite clearly shows that the bigger and heavier Boeing 777-9X is still more efficient, although Airbus tries to convince customers as well as investors this is not the case.

*This analysis does not take into account the mass of the cabin. Assuming the cabin mass is about 9,000-10,000 kg, the advantage for the Boeing 777-9X increases to 7%.*

In my next article I will compare the Boeing 777-8X and the Airbus A350-1000, since both aircraft transport equal numbers of passengers. I will also draw conclusions for the comparisons made and look which aircraft family will eventually be the winner.

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