Back to the 1930’s? Air NZ to weigh passengers.

Surely it'll show that median weights for both sexes have increased?

A newspaper article said that in 2021, CASA in Australia (for aircraft seating 150 to 299 passengers) recommended adult males be considered as having a weight of 81.8kg whereas females were assumed as 66.7kg each. Unlike the USA, this doesn't include carry-on bags that most Oz airlines never weigh.

IIRC, about two thirds of adult Australians are overweight or obese with this percentage having (excuse the poor pun) grown over the last 30 years.

Bringing items heavier than seven kilograms on board, which many seem to do, must alter the equation, at least at the margin.
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They should do it every time, for every passenger. If nothing else, it would provide some amusing youtube videos.

More seriously, I think the weights being used were well off the mark, especially for the USA, but increasingly for our area. It all adds up.
Seems a pointless exercise given it’s voluntary. I’m guessing it will be the larger pax more likely not participate, skinny people will have no problem, so the results will be skewed.
Looks like other airlines too are exercising the weigh-in:

Don't know why its voluntary and not mandatory for the survey period. Like any flight directive - no weigh, no fly.
Perhaps load cells on the landing gear (maybe they already have them) and can check it empty then loaded divided by head count and there's your average.
It's a great idea and should be done, and those under the average weight should be given bonus points or cash part refunds to reward them for contributing to fuel economy.
The missing part is that the checkin staff don't actually see the weight figure. It's collected by the scale anonymously and not displayed, and then back-office will calculate the new average and report it. There's no reason not to step on the scale, and bigger people should be doing it, because the figures are used to drive regulations. If it turns out the average has dramatically increased, regulations would have to be updated to support that.
Knowing the weight is being displayed in a non local area would help I would think .
When I last did it on an NZ flight (which must have been around 5 years ago, co-incidentally) they had a station set up in the aerobridge, positioned after you scan your boarding pass at the gate entrance (so no way you could pass things off to someone else to hold while you were weighed, absolutely everything going down that aerobridge and onto the plane was weighed). There was no obvious display of the result, and the person sitting behind the desk looked like an IT analyst (not in NZ uniform), rather than an airline check-in agent (who might be tempted to try and enforce weight limits - as there were two scales covered with cardboard; one for you and one next to it, for your carry on items). So, while NZ uniformed staff helped direct you onto the scales, there was no sense of guilt for; how much you weighed, how much your bags weighed, or whether anyone other than the IT person (who was just constantly looking at their computer screens, not the passengers) could see the what was going on, thankfully.
I am fat, I would get on the scales .
Knowing the weight is being displayed in a non local area would help I would think .
While it is being recorded, I doubt anyone actually see the weight associated with you individually. All that anyone needs to know is that it was recorded correctly.