In the airline industry the use of standard weights for pax is a well known thing and works well enough as it averages out most of the time. If you get an airliner full of average people, the suomi fighter will be compensated by some bird seed feeding vegan adult and it is relatively rare that you get a beer belly club travel in mass. While there are massive discussions about what these planes really weigh on take off (where it really matters) they mostly stem from “handluggage” where most people seem to put whatever they can not fit into their checked (and weighed) baggages. Most airlines still treat handluggage as a thing they don’t want to fight about, the only time I really saw fights over handluggage was at Air Lingus, where they bodily retrieved what they considered oversize luggage from the passengers… the ugliest scene I ever withnessed in over 35 years of airline flying. Yet, I would say that it is quite obvious that the IATA pax weights are optimistic not so much for the average adult but for the handluggage. More than once I have seen pax struggling with handluggage which actually fit the size but definitly not the weight.
In GA however, these kind of average weights do not play as you don’t have enough pax to distribute them with and you always use seatrow trim too. So in reality, you need to be fairly sure how much just every thing weighs on the plane to get a proper load manifest. Only putting the garbage neccessary items you carry on each flight on the scale sometimes yields eyewatering results… Let’s see, two bottles of oil, toolbox, airplane cover, headsets, pilot bags, tie down kit, airplane docs and so on and then you see a 10 kg figure? Really? And then you get the pax baggage even for a short roundtrip where they carry their favorite kitchen sink just because it was lucky last time.
If you want to be gentlemanly about it and not ask, then the only save way is to up the averages to say 100 kg per adult including 1 piece of carry on baggage. And I’d recommend to load each piece of baggage yourself, so you can get a feel for what is in those bags. Particularly ladies handbags can be very deceiving… and pilots bags too.
Most of the time, if you load half the seats a plane has you ought to be ok. But particularly for distance travel over several days or weeks, even that can be a challenge if your travel mates are of the Business Class type who buy C-Class tickets only for the 2nd suitcase they can carry and at the destination bring back a full rock collection. If you need a pick up truck to go see the in laws for tea, you usually know you are in trouble flying.
In short, guessing is fine mostly but can bite like one of thos Australian crocodiles if you get it wrong.
A friend from the US who was an FO in the MD-11 for World Airways (who did lots of contract work for the US military) told me that after a very sluggish takeoff out of Hawaii, he figured they were something like 12,000 lbs overweight. Apparently standard passenger and baggage weights had been used for a flight full of heavily built US Marines with full kit. There was no birdseed eating vegan on that flight to balance things out so to speak.
Not shabby for an MD11… 6 tons is noticable if not fatal in most cases. Incidently, that was about the weight the Concorde who crashed at CDG was overweight over RTOW too.
Good example alioth. One would assume that World should know their clientele though, they do this for a living as far as I know. Fully equipped Marines…yikes. while the guys and girls on board may well be within the average, their baggage could easily compete with foreign workers on the way to their summer homes… the scary bit is they can actually lift all of this and carry it around. I guess the load controller that day got a telling off which left him with a permanent tinitus…
Mooney_Driver wrote:
If you want to be gentlemanly about it and not ask, then the only save way is to up the averages to say 100 kg per adult including 1 piece of carry on baggage.
That’s actually pretty close to the standard masses for small aircraft in part-CAT (AMC1 (c) to CAT.POL.MAB.100(e)) For aircraft with 1-5 passenger seats, 104 kg for male adults and 86 kg for female adults.
alioth wrote:
A friend from the US who was an FO in the MD-11 for World Airways (who did lots of contract work for the US military) told me that after a very sluggish takeoff out of Hawaii, he figured they were something like 12,000 lbs overweight. Apparently standard passenger and baggage weights had been used for a flight full of heavily built US Marines with full kit. There was no birdseed eating vegan on that flight to balance things out so to speak.
There was a fatal crash 1989 in Sweden when a Beech 99 on a scheduled commercial flight stalled during approach. The aircraft was well outside rear GC limits because the actual mass of passengers seated in the rear was much higher than the standard mass used at the time (75 kg). There was much publicity around the crash as 3 MPs died together with a high-ranking civil servant.
I guess it all depends on the people that surround you.. 100kg as an average for me would be crazy (high), but my “demographics” are generally 1) gender mixed and 2) in their 20-30s.
Including luggage, if say 85 / 65 (if overnight trip) is likely plenty.
I might get to 100 myself but only for a week long trip where I take also take my bicycle.
Airborne_Again wrote:
For aircraft with 1-5 passenger seats, 104 kg for male adults and 86 kg for female adults.
Does that include baggage or not? Would work out however. Do you know what the standard weights for kids and infants are? 43 and 11 kgs as they used to be?
Lazy as I am I always thought 100kg is something even a mathematical genius like myself can work out without a calculator 
Obviously this means that most 4 seaters in fact seat 2 seaters in most cases, but of course this does not mean you can not do a “proper” WnB if the actual weights obviously differ from the standards. In fact, using the standards as pre-plan and the real ones on the flight should give a proper safety margin.
After hitting a fence after aborting a take-off, uphill, on long grass, but into wind, on the island of Stronsay, we weighed ourselves and everything in the plane. On take-off at Inverness, with full fuel, we’d just been under max weight.
We were well within it at Stronsay. C of G was no problem.
We regularly flew together, so didn’t calculate before flight. The surprise was how near the limit the junk had taken us. (Not our flightbags and lifejackets.)
I’ve been much more cautious since, and plan take-off from such runways very differently from the standard training departures.
Mooney_Driver wrote:
Does that include baggage or not?
It includes hand baggage.
Would work out however. Do you know what the standard weights for kids and infants are? 43 and 11 kgs as they used to be?
Children 35 kg. Infants sitting in the lap of an adult are not counted, with their own seat they count as children.
One long haul airline pilot tells me they work on 120kg per passenger, including luggage.
