Finland's national carrier Finnair is asking passengers to be weighed voluntarily and anonymously so that it can update their standard weight figures.
Almost everything that gets onto a commercial plane — fuel, checked-in baggage, cargo and meals — is weighed. For passengers and their cabin bags, most airlines use average data.
But Finland’s national carrier Finnair said Friday that it started asking passengers this week voluntarily and anonymously hop onto a scale with their hand luggage at the country’s main airport in Helsinki, the airline said Friday. The aim is to get their own figures.
“We will need data for both winter season and for summer season — in winter season people typically have heavier clothing, which impacts weights,” Finnair spokeswoman Päivyt Tallqvist told The Associated Press, adding that the survey would last until May.
Passengers boarding onto European and long-haul flights won’t be “penalized for their weight,” and “the numbers are kept discreet, away from prying eyes,” she added.
Weight and weight balance is a big deal for aircraft stability. For example, a bunch of weight in the back of the plane will cause it try to pitch up more, which can matter quite a bit when landing.
I think it can be compensated for to some small degree. But... A deeper explanation is needed.
A plane has a center of mass (or gravity) which is the gravity balance point of the plane. It also has a center of lift which is like the center of gravity but for the lift force of the wing. See pic:
If the center of lift and center of gravity aren't in the same horizontal location along the length of the plane, the plane has a net force that rotates the nose up or down.
It's like if you had a yard stick and balanced it on your finger. And then added a weight somewhere between your finger and one end. The yard stick will start to rotate (tilt).
The horizontal stabilizer applies a force as well, and it is trimmed to balance the other forces and set the angle of attack (pitch) of the plane. The elevator allows momentary adjustment of pitch.
I may not describe this perfectly but... When a plane has too much weight towards the rear, it will be unstable (and dangerous) to fly. When a plane has too much weight towards the nose it will be somewhat sluggish but stable.
Balancing nose heavy is preferable to tail heavy in general due to the stability issue. A little bit of tail heavy is a bit dangerous and a bit of nose heavy is no big deal. I think another factor is that the tendency of a plane to pitch up could result in aerodynamic stall (loss or lift). Of course, if a plane is too nose-heavy, you can't climb.
Front to back balance is really important to how the plane handles. Side to side balance matters but in terms of passengers / cargo, they're more narrowly distributed about the center of the plane compared to their distribution front to back.
I imagine that there will be a lot of FUD about this given the general lack of knowledge about how airplanes actually work and what center of gravity is all about.
I’d be uncomfortable if large aircraft were operating so close to tolerances that it made this kind of thing necessary. I’ve been on small aircraft where they’ve asked passengers to switch seats before takeoff to balance out the load (I’m assuming there’s a scale readout on each wheel).
Assuming they have those data already, I’m not sure how per-flight data would change what they’re doing (as opposed to averaging), unless they’re talking about tiny planes.
I mean, sure maybe. But we’re talking about highly engineered systems here. They should already have tightly understood error bands.
Again, for the puddle jumpers, I can see it. I’ve been on planes with 20-30 seats where they reassigned passengers before takeoff (again, probably based on load data from the wheels), and that makes perfect sense to me. If we assume a model where people pick a seat at random, there will be some percentage of flights where too many people (or at least too much weight) lands on one side of the plane. But as someone whose flown in everything from tiny helicopters to C-130s to giant international commercial airliners, there’s a point where the capacity of the plane should so vastly over-exceed its load that it just doesn’t matter.
That might be the case here, but the article doesn’t specify.
When they start talking about weight in long haul flights it's the end goal. Weight =fuel, unless you're in something like a sea plane where the balance of the aircraft is important.