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On Wikipedia you often find aircraft specified with a separate "gross weight" and "MTOW". The term "gross weight" implies "weight with maximum fuel and payload". Yet this is not the case, since the MTOW is given separately.

I tried googling 'gross weight Vs MTOW" and got this.

  • Gross Takeoff Weight: The weight of the airplane just before brake release to begin the takeoff roll.
  • Useful Load: The weight of crew, cargo, passengers, baggage, and usable fuel.
  • Maximum Ramp Weight (MRW): The maximum weight for ground operations.
  • Maximum Takeoff Weight (MTOW): The maximum weight for takeoff.

As you can see, not only is the term "Gross Weight" not used directly, but the term that is used has a definition that isn't particularly helpful in this context.

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    $\begingroup$ Not sure where you found this definition: "gross weight" implies "weight with maximum fuel.amd payload". That is certainly not the correct definition. $\endgroup$
    – Bianfable
    Feb 24 at 10:31
  • $\begingroup$ Sounds like a Wikipedia problem to me. If I'm reading a "Gross Weight" value in a Wikipedia entry I would tend to think they are probably giving the max allowed Gross Weight, although they really should say so explicitly. As far as splitting hairs between max ramp weight and max takeoff weight, I dunno. Basically, if you are giving one single number for "Gross Weight" without any further explanation, then you are not being very precise in your terminology. As to why that number should be different from MTOW or MRW, who knows. Which is usually given as the higher number, GW or MTOW? $\endgroup$ Feb 29 at 16:16
  • $\begingroup$ (In your linked B-29 example MTOW was the higher number, noted as "combat overload", so maybe the GW number is some sort of original designed max TOW or RW?) $\endgroup$ Feb 29 at 16:23

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The gross weight is the current total weight of the aircraft. It is basically the value a scale would show when putting the aircraft on it. It obviously changes all the time, e.g. when payload (passengers or cargo) is loaded/unloaded or when the aircraft if refueled and also during the flight as fuel is burned.

The Maximum Takeoff Weight (MTOW) is a legal limitation given by the aircraft manufacturer. It is the highest value for the gross weight at which the aircraft is certified to take off. When the gross weight is higher than MTOW, you are not allowed to take off.

References:

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  • $\begingroup$ Then why on earth is it specified at a certain value? $\endgroup$ Feb 24 at 10:43
  • $\begingroup$ @AbdullahisnotanAmalekite Yeah, that doesn't make sense. Can you show an example? I looked at a few Wikipedia articles for aircraft specifications and couldn't find one that specifies gross weight. $\endgroup$
    – Bianfable
    Feb 24 at 10:44
  • $\begingroup$ en.wikipedia.org/wiki/Boeing_B-29_Superfortress $\endgroup$ Feb 24 at 10:55
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    $\begingroup$ @AbdullahisnotanAmalekite That Wikipedia article uses this NASA table as a source. No idea what they mean with $w_g$. Maybe typical gross weight? $\endgroup$
    – Bianfable
    Feb 24 at 11:00
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    $\begingroup$ @Bianfable: the full NASA report defines $w_g$ as "design gross weight". I suspect this is simply a fancy terminology for the maximum taxi weight $\endgroup$
    – sophit
    Feb 25 at 20:16

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