http://www.aljazeera.com/news/asia-paci ... 21877.html

Surprised this hasn't caught on over here with certain budget airlines.

It's only a matter of time me thinks.

It's silly. If you divide the weight of the aircraft itself by the number of passengers, the varation in weight of the people is a small factor. Most of the fuel in the plane is used to get the plane itself from A to B, the people are just along for the ride.

Take a typical airliner, say an a321-200. That carries 200 people, give or take, including crew. Say each person weighs 80Kg and has 20Kg of luggage (it makes life easier, but they are reasonable numbers) - therefore the total weight of 'personal cargo' is 20,000Kg. The standing 'empty' weight of an unfueled a321-200 is 48,500Kg and it carries 24,000 litres of aviation fuel at takeoff which weighs another 19,000Kg, roughly. Therefore the the take off weight of an 'empty' A321-200 is more or less 66,000kg. The plane itself weighs over three times as much as the people it carries. The idea passenger weighing 100Kg makes any difference compared to a passenger weighing 80Kg is nonsensical.

While I totally agree I suspect this is more about the passengers who weigh nearer to 200kg than 100kg, especially when you consider that the rate of obesity in Samoa is well above average (clickety.
The other thing not to overlook is when has common sense and decency stopped an airline making a fast buck?

The weight per-seat of your unladen aircraft is ~240Kg so the "personal cargo" of 100Kg per seat is a very significant percentage. Also, the amount of fuel required increases at an increasing rate per Kg of cargo due to the significant added weight of the fuel itself.

If I could find the laden and unladen fuel consumptions of take-off and cruising then we could put an actual figure to it, but the best I can do is guestimate an approximately linear relationship between total weight and total consumption as a lower bound. In that case, a reduction per-person from 110Kg to 100Kg would reduce the fuel required by almost a 3% saving of 678litres, at a cost of about $1000 or $5 per head for the max haul journey.

Guess what? That's about what they are charging.

It's not a glider y'know. It's nearer 330kg assuming its going anywhere. So if we consider the total amount travelling per ticket is roughly 410kg, adding an extra 20kg of weight is a less than 5% increase in total weight. I consider less than 5% to be an insignificant amount. The amount between 'passenger' and 'no passenger' is obviously significant but a jetliner with no passengers is a pretty pointless object. They do sometimes fly empty planes around but any airline that does that often is going out of business.


I don't dispute your maths, however I do dispute your basis of calculation. You're suggesting the average weight of a group of passengers is 110Kg rather than a standard average with a few (excuse me but..) fatties. And no children. If your average passenger weighs 110Kg, you're probably better off reducing the capacity of the plane so they all fit in, thus bringing the 'cargo weight' back into line with my original calculation and negating the extra fuel cost into the bargain. Course then you're selling less tickets per aircraft...

As Davros says though, few things stand in the way of a quick profit in the airline industry...

I don't understand what point you're trying to make?

I used all your figures which seemed like reasonable averages - 80Kg per person plus 20Kg baggage - then added the 10Kg extra to give an example excess. I could have used X Kg and differentiated cost dX but since this is on the back of an envelope, I just used my fingers. Re-calculating for 90Kg (-10 rather than +10) gives a pretty similar delta.

Kicking people off the plane to bring the weight down would also cost a similar amount within reason; the linear model starts to break down if a single passenger (including luggage) weighs in excess of ~500Kg.

The other thing that needs to be considered are that it is a small airline with very small aircraft flying between islands so big people make a difference. Remember Aliayah who was killed when her private plane was overloaded with film equipment. So it does happen.


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The concept of paying purely by weight is just as flawed as paying by seat, if not more so.
You'd need to divide the weight of the airliner by all the seats available and add that to baggage and passenger weight to get a 'fair' price.
I'm fat, but I take the same share of the weight of the airliner as a twelve year old in the same seat.

Actually, as Amnesia points out these are very small aircraft carrying a small number of people up to a certain maximum load. If their average passenger is obese then they may well have to fly with a significant number of empty seats, so a fat person does take up more than one seat.

An example given in the article is "they're paying [for] 200kg, so they deserve to get 200kg of comfort" which could be read to mean a larger seat or two seats.

It does depend on the size of the aircraft. In a small 4/6 seater aircraft the weight of individual passengers is crucial when it is a 12 seat aircraft it becomes the average weight that is more of a factor. In big aircraft the size of the aircraft is more than enough to cope with the odd obese passenger. It then becomes a problem of comfort for passengers and profitability for the airline as heavier passengers require more fuel, but it will not be enough to bring down an aircraft as they usually have sufficient surplus power and fuel to cope.


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