WTF is Gross Weight?

birdus

birdus

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Jay Williams
For many, many, many years, I thought I knew what gross weight meant. Today, however, I was looking at the Wikipedia article for the A-4 Skyhawk, and it says:
  • Gross weight: 16,216 lb (7,355 kg)
  • Max takeoff weight: 24,500 lb (11,113 kg)
I wondered how max takeoff weight could be more than gross weight, so I looked up "Gross Weight" and this is what Wikipedia says gross weight means:

"total aircraft weight at any moment during the flight or ground operation"

Am I the only one who has always thought that "gross weight" meant "the highest weight an airplane is certified to fly at" or something along those lines? At least now I know that I don't know what gross weight means.
 
Could it be ‘gross weight’ is the weight for that particular flight? The ‘max takeoff weight’ is the real max. Then we have performance for given conditions.
 
I think “typical GW”would be a better way of phrasing it. Then list the aircraft’s max GW / take off weight separately…which may or may not be the same as max landing weight.
 
Apparently MGTOW doesn’t mean what I thought it meant.
 
Gross Weight is whatever the entire aircraft, including payload and fuel and all, weighs right now.
As opposed to Net Weight or Tare Weight or several other types of weight.
Max Gross Weight would be the maximum it can weigh.

Actually, I just looked through 4 fairly modern POHs and the word "Gross" wasn't actually used at all. "Maximum Ramp Weight" and similar terms were used.
 
I don't know the answer to the original question, but I suspect none of the above is correct either. A guess: Gross weight is the weight of the fueled and loaded aircraft and MTOW is with external armaments.
 
DoubleD said:
I don't know the answer to the original question, but I suspect none of the above is correct either. A guess: Gross weight is the weight of the fueled and loaded aircraft and MTOW is with external armaments.
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probably a pretty good guess. Different versions of the A-4 had different max payloads, but they’re around 8000 lbs, give or take.
 
You can also have an aircraft with a minimum gross weight. Which further illustrates that the term “gross weight” doesn’t mean the highest weight an aircraft can fly at.
 
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I think, in this case, gross weight refers to the aircraft with full fuel. Max Take-off would include armament too. Not that I think it's correct to say that. It is a wikipedia article. You should log in and fix it.
 
Gross weight is exactly what the definition states. That’s the total weight of the aircraft at any given time on the ground or in the air. That’s not just a wiki definition, that’s an FAA definition.

The gross weight would also include expendables if applicable. That doesn’t mean it’s at its max gross weight though. You can also have different max gross weights for a particular aircraft depending on loading.
 
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I'm going to be getting my complex endorsement soon, and so am reading the POH for the Piper Arrow (just started reading 5 minutes ago). Near the beginning of the document, it says this:

"Performance figures are for airplanes equipped for cross-country transportation and flown at gross weight under standard conditions at sea level or stated altitude."

On the next page, under "Weights," it says:

Gross Weight (lbs): 2500

Some people here are saying the same thing the Wikipedia article says. Someone needs to tell the folks at Piper that they don't know what the hell they're talking about, because what the POH says sure doesn't mean "whatever the airplane happens to weight at some random point in time."

How exciting!
 
birdus said:
I'm going to be getting my complex endorsement soon, and so am reading the POH for the Piper Arrow (just started reading 5 minutes ago). Near the beginning of the document, it says this:

"Performance figures are for airplanes equipped for cross-country transportation and flown at gross weight under standard conditions at sea level or stated altitude."

On the next page, under "Weights," it says:

Gross Weight (lbs): 2500

Some people here are saying the same thing the Wikipedia article says. Someone needs to tell the folks at Piper that they don't know what the hell they're talking about, because what the POH says sure doesn't mean "whatever the airplane happens to weight at some random point in time."

How exciting!
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They got better at it. My Piper Lance POH says maximum takeoff weight and maximum landing weight. In the charts section they use gross weight and it is the same as maximum takeoff weight.
 
birdus said:
For many, many, many years, I thought I knew what gross weight meant. Today, however, I was looking at the Wikipedia article for the A-4 Skyhawk, and it says:
  • Gross weight: 16,216 lb (7,355 kg)
  • Max takeoff weight: 24,500 lb (11,113 kg)
I wondered how max takeoff weight could be more than gross weight, so I looked up "Gross Weight" and this is what Wikipedia says gross weight means:

"total aircraft weight at any moment during the flight or ground operation"

Am I the only one who has always thought that "gross weight" meant "the highest weight an airplane is certified to fly at" or something along those lines? At least now I know that I don't know what gross weight means.
Click to expand...

Q. If Gross weight is the weight an aircraft is certified to fly, what were you calling the aircraft weight between Basic Empty Weight and Gross Weight?
 
So the lesson is that people inappropriately shorten language all the time resulting in a lack of clarity, and so you have to make sure you know what it means where you read it?
 
I think that in the official dictionary definition of the word "gross" the following would apply in this case:

B. of or concerning only the broadest or most general considerations, aspects, etc.

There, that should clear things up...
 
keen9 said:
So the lesson is that people inappropriately shorten language all the time resulting in a lack of clarity, and so you have to make sure you know what it means where you read it?
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Yes.

you can get training from a CFI…Or possibly a CFII who isn’t a CFI. :rolleyes:
 
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Clip4 said:
Q. If Gross weight is the weight an aircraft is certified to fly, what were you calling the aircraft weight between Basic Empty Weight and Gross Weight?
Click to expand...

Weight.
 
Love this forum, it forces me to look up stuff I thought I knew!

So I've done a little research, and the short answer (IMHO) is that:
Gross Weight is "the loaded weight of the airplane" (See 1978 C172N POH, Definitions section)
Max Gross Weight is the max loaded weight at which the aircraft may be operated, without specifying whether it's for ramp, takeoff or landing. (See FAA Handbook of Aeronatutical Knowledge, where it's not explicitly stated, but one can draw this conclusion by the way in which "Gross Weight" is used)

As a side note: I looked over 10 or so POHs that I have, and most of the older ones use Max Gross weight, where most of the newer ones don't, instead using the more granular terms, such as Max Takeoff or Max Landing Wt etc... Interestingly, the 1978 C172N model, which has Gross (Loaded) Weight in its definitions, doesn't seem to actually employ the term later on in the limitations section, possibly because it's not actually a limitation.

HTH

Matt
 
MattC said:
Love this forum, it forces me to look up stuff I thought I knew!

So I've done a little research, and the short answer (IMHO) is that:
Gross Weight is "the loaded weight of the airplane" (See 1978 C172N POH, Definitions section)
Max Gross Weight is the max loaded weight at which the aircraft may be operated, without specifying whether it's for ramp, takeoff or landing. (See FAA Handbook of Aeronatutical Knowledge, where it's not explicitly stated, but one can draw this conclusion by the way in which "Gross Weight" is used)

As a side note: I looked over 10 or so POHs that I have, and most of the older ones use Max Gross weight, where most of the newer ones don't, instead using the more granular terms, such as Max Takeoff or Max Landing Wt etc... Interestingly, the 1978 C172N model, which has Gross (Loaded) Weight in its definitions, doesn't seem to actually employ the term later on in the limitations section, possibly because it's not actually a limitation.

HTH

Matt
Click to expand...

Great! Thanks for that info, Matt!
 
keen9 said:
So the lesson is that people inappropriately shorten language all the time resulting in a lack of clarity, and so you have to make sure you know what it means where you read it?
Click to expand...
Yep pretty much. The sequence seems to be.
  1. Clearly defined term or concept.
  2. Gets shortened for convenience (or make a mnemonic for it - same thing).
  3. People start thinking the shorthand is the official term.
  4. And start misunderstanding it, wondering what it means, or complain it's vague.
 
Velocity173 said:
Gross weight is exactly what the definition states. That’s the total weight of the aircraft at any given time on the ground or in the air. That’s not just a wiki definition, that’s an FAA definition.
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I agree. The gross weight changes in the air by burning fuel and changes on the ground as you add or remove payload.
 
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