Wednesday, September 15, 2010

Weighing Passengers Before Travel

When you think about it, getting a plane to actually take off and fly across countries and oceans is absolutely amazing. An incredible amount of energy is consumed, expelled and transformed into movement and, thanks to Bernoulli's principle, lift.

Taking off is a balance between gravity, the total mass of the plane and the amount of lift that is available. Too much mass aboard and you aren't going anywhere.

If you are like me then you never thought about how all this weight is calculated. The base weight of the plane as well as the weight of the fuel onboard is known, and checked bags are weighed before every flight. What about the passengers and carry-on luggage. We don't get weighed before each flight so how do they do it? They use an average traveler weight.

This makes sense, but where does this average come from? They weigh people with their carry-ons. Since the average weight of people will fluctuate based on the population traveling and why they are traveling, there is a shift in this average passenger weight every now and then.

Even airline policy can affect this average weight. While increased baggage fees reduced the number of checked bags, you can be sure that it increased the weight of passenger's carry-on bags as passengers try and avoid additional travel costs.

This weighing is done regularly in order to ensure that the average remains accurate, but I've never actually taken part in one. Traveling quite a bit for 7 years you would have thought that I would have run into this before, but travel still surprises me every now and then.

On a recent trip on Air Canada from Toronto, ON to Boston, MA I heard the following message (more or less):

In order to calculate the amount of weight that is on the plane, we need to know the total weight of the passengers and the carry-ons aboard. To spare you from the embarrassment of being weighed before each flight, we use and average weight for each passenger with their carry-ons. In order to ensure the accuracy of this average, we routinely need to take new weight measurements. Today we are conducting just such a measurement.

As you board, you will be asked to step on a scale with all of your carry-on bags. The weighing only takes a few seconds and it is completely anonymous. Thank you for your cooperation.

In front of the boarding gate, two men with small metal scales attached to laptops set up their weigh station. Just like the announcement said, the weighing only took a few seconds and it was minimally intrusive. It was completely anonymous and no one was taken aside or denied boarding for exceeding a weight limit.

To all of those who read this article looking for a rant about how each passenger should be allowed a total combined luggage and body weight allowance, I apologize, but I hope that you learned something regardless.

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  1. Well, as weird as it might seem to be weighed before a flight - this is actually reassuring to me! Better that they are working with known weights than unknown. It's certainly true that the average weight is varying more now as passengers try to avoid checking their baggage. However I've never seen this actually happen in a US airport! The only time I was weighed before flying was when I was one of 4 passengers (including the pilot) boarding a 4 passenger Cessna bound to cross the Amazon jungle. Sounds exotic I know - and you can be sure it was! :-) But I was more than happy to be weighed beforehand knowing it might avoid a weight imbalance...and in a tiny Cessna like that - a crash.

  2. Thromby Air are already doing this:

    Also, we have an automated passenger sizing system:

    Robert E. Coli
    CEO Thromby Air - Lowest of the Low