Weighing The Boeing 777-9

| About: The Boeing (BA)


Boeing 777-9 empty weight is likely going to be 184t-185t.

Aircraft is much heavier than the Airbus A350-1000.

-9 is built to specification of customers.

In my previous article about the Boeing (BA) 777-9 empty weight, I tried to provide a better pointer for the actual empty weight of the aircraft. The earliest estimates were around 190,000 kg, which later was lowered to roughly 188,200 kg. This figure, however, was still quite high and using a ‘sum of all parts’-approach, my new estimate currently is 184,600 kg.

Source: Boeing: The Boeing Company

In this article, I will not be looking at the component weights of the aircraft, but some characteristic weight data for the aircraft to come up with a second estimate for the empty weight of the aircraft.

Understanding the method

Figure 1: Example weight breakdown Boeing 777-300ER (Source: www.AeroAnalysis.net)

Before I dive into the simple math, it is important to understand how it works. Every aircraft has a certain empty weight and the more passengers you can transport within that structure, the lower the empty weight per seat. Weight plays an important role, since obviously more fuel burn is required for a heavier structure than for a lighter structure with the same aerodynamic efficiencies.

The maximum ramp weight is the weight of the aircraft at the ramp, which includes the operating empty weight of the aircraft, the payload, the mission fuel, taxi fuel, and run-up fuel.

When the taxi fuel and run-up fuel is consumed, the aircraft cannot be any heavier than the maximum take-off weight, which includes the operating empty weight of the aircraft, the payload and the mission fuel.

The operating empty weight (OEW) and maximum take-off weight (MTOW) can be considered as the upper and lower bounds of the aircraft. What is in between is the combination of fuel and passengers. A possibility is to add all fuel possible to the tanks and then add passengers until MTOW is reached, or first fill up the cabin and after that fuel the tanks until MTOW is hit. If an aircraft hits MTOW before the fuel tanks are filled, the aircraft is said to be weight limited; if the fuel tanks are full before the MTOW is hit, the aircraft is said to be fuel limited.

If we do not know anything in between the OEW and the MTOW, it is not possible to come up with an OEW estimate for the aircraft. Luckily, each aircraft has a maximum zero fuel weight (MZFW), which includes the maximum structural payload and the empty weight of the aircraft without fuel. So if we know the maximum structural payload and the MZFW, we can estimate the OEW of the aircraft.

The numbers for the Boeing 777X

The maximum zero fuel weight can be obtained from the brochure for the Boeing 777-9, which is 254,918 kg. The harder part is determining the maximum payload of the aircraft.

To get an idea, I compiled a list of reference aircraft:

What we see is that the passenger weight accounts for roughly 50-60% of the maximum payload weight. With the Boeing 777X, the company has decided to keep the MTOW constant, which gives the impression that the jet maker is not aiming for a big increase in the maximum structural payload weight of the aircraft. This is amplified by the fact that the fuel capacity of the -9 will increase by roughly 9%. With that in mind, I am expecting that Boeing is betting on filling the seats in the cabin and not so much the cargo containers in the belly of the aircraft. This does make sense, since adding belly freight capacity to an aircraft directly means that the company is adding pressure on its own cargo aircraft.

For the Boeing 777-9, I am expecting that roughly 59% of the maximum payload will be in the cabin (meaning passenger and their luggage), while 41% will be for air freight. This would yield a maximum payload weight of 70,300 kg, which is roughly 450 kg higher than on the Boeing 777-300ER.

If we now subtract the 70,300 kg from the value for the MZFW provided by Boeing, we find an empty weight of roughly 184,700 kg.

Comparison and final thoughts

If we compare the sum of all parts method from the first part of this two-part article series with the payload weight method, we see that the second method gives a weight that is 100 kg higher. Both methods point towards a significant increase in the OEW, but this was to be expected since Boeing never aimed to provide a direct Boeing 777-300ER replacement. In a same sense, the Boeing 777-9 is also not intended as a competitor for the Airbus A350-1000 which per Airbus website seats 366 passengers in typical configuration and therefore cannot be compared to the 414-seat Boeing 777-9 in a sensible way.


For investors, it is important to know what the Boeing 777-9 is supposed to do and what it clearly is not supposed to do. One of my readers pointed out that the Boeing 777-9 most probably cannot compete with the Airbus (OTCPK:EADSF) A350-1000 due to the weight for the Airbus A350-1000 being multiple tonnes lower. While this is true, it is important to note what Boeing is doing here.

With the -9, Boeing is moving away from the range-payload position of the Boeing 777-300ER and is trying to find a sweet spot for the Boeing 777-9. The current payload-range spot comes directly from customer feedback, where Boeing is already providing a replacement for the Boeing 747-8I and is probably also taking into account a scenario in which the Airbus A380 production comes to an end.

In my view, the Boeing 777-9 is Boeing's effort to remain leading on the wide body market... A move that should benefit investors over the long term. Given that the narrow body product that Boeing currently has is a strong one but is still being outsold, it is important that Boeing launched the -9 since a single widebody jet sale could bring 3-4 times the money of a narrow body jet sale.

With the -9, Boeing counts on the replacement of the installed base as a main advantage for the jet where it recognizes the inability to directly compete with the Airbus A350-1100, but keeps pressure on the A380, settles in a new spot on the market, and provides a 747 replacement all at the same time.

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Disclosure: I am/we are long BA.

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