I know a lot of people who would probably be too embarrassed to be weighed and wouldn't fly.
They could scan your ticket into the body scanner to identify/validate your ticket, and then it spits the weight back into the airline's computers for balance calculation.
But for a small flight with 6 passengers (which is the case most important to get right) it's probably going to be a manual affair.
That said - people might have all kinds of things they feel are embarrassing, such as removing their shoes which might be required in security. While I don't agree with TSA routines much - I still don't think we should care what people feel is embarrassing. Get over the embarrassment, fix your weight or avoid flying are 3 very real options.
Anecdote: I flew a Cessna 6 seater in Venezuela and couldn't sit next to my wife, instead had to sit next to a 50kg sack of frozen chicken (the implication being that me and the chicken were the lightest, and my wife was heavier than the chicken sack by enough). I laughed and laughed. Pro tip: don't laugh.
If only my anorexic friend had known sooner that she just needed to work on her weight, she could have avoided things like nickel-and-diming airlines. (not only so I think the distribution claim is bogus, but it's a precursor to billing by passenger weight)
In general aviation just because the seat is there doesn't mean you can take off with someone in it. As a rule of thumb, "one seat" is a 150 pound person, no luggage, and sometimes that's counting some of your fuel there too. A 2-seat aircraft like the Cessna 152 doesn't take off with full tanks with 2 average adult males onboard even without luggage (360 pounds full-fuel payload), and it's a struggle to get off the ground with 2 heavier adults even with reduced fuel.
The C172 is a four-seater aircraft, 577 pounds full-fuel payload (note: less than 150 lbs per seat!). So with full fuel tanks you will get one pilot, one passenger, and either some luggage/cargo or a child passenger. Maybe a second adult passenger and no luggage if nobody is too heavy (above 175 lbs average). And an over-water flight in the Pacific is not the trip to take with a reduced fuel load. So you can see how the numbers work out here: the pilot plus one obese adult might literally be the entire payload for the flight.
(Note: a 2003 study from the New Zealand Ministry of Health set their "average" male passenger weight at 187 lbs without carryon, or 207 lbs with carryon, and the average female passenger weight at 159 lbs without carryon or 169 pounds with. Further, they noted that average passenger weight was increasing at about 2 kg/6.6 lbs per decade.)
source: https://www.caa.govt.nz/pubdocs/2003_pax_weight_survey.pdf
> Yes: because Samoa Air's fleet aircraft are all Cessna 172s. You are essentially paying for a personal charter flight in a small aircraft, so there are no "averages" there. A single obese passenger can directly increase a flight's payload weight by +100% or more. Not the case with an airliner, where you are averaging across 75-600 people.
> In general aviation just because the seat is there doesn't mean you can take off with someone in it. As a rule of thumb, "one seat" is a 68.03 kg person, no luggage, and sometimes that's counting some of your fuel there too. A 2-seat aircraft like the Cessna 152 doesn't take off with full tanks with 2 average adult males onboard even without luggage (163.29 kg full-fuel payload), and it's a struggle to get off the ground with 2 heavier adults even with reduced fuel.
> The C172 is a four-seater aircraft, 261.7 kg full-fuel payload (note: less than 68.03 kg per seat!). So with full fuel tanks you will get one pilot, one passenger, and either some luggage/cargo or a child passenger. Maybe a second adult passenger and no luggage if nobody is too heavy (above 79.37 kg average). And an over-water flight in the Pacific is not the trip to take with a reduced fuel load. So you can see how the numbers work out here: the pilot plus one obese adult might literally be the entire payload for the flight.
> (Note: a 2003 study from the New Zealand Ministry of Health set their "average" male passenger weight at 84.82 kg without carryon, or 93.89 kg with carryon, and the average female passenger weight at 72.12 kg without carryon or 76.65 kg with. Further, they noted that average passenger weight was increasing at about 2 kg/6.6 lbs per decade.)
> source: https://www.caa.govt.nz/pubdocs/2003_pax_weight_survey.pdf