Dear Umbra,

Your recent answer to the plane/train question prompts me to ask something that has always bothered me but that my little old brain can’t figure out on my own. I know that planes are worse than other forms of transportation, but the plane is going to fly whether I’m on it or not. So I always wonder if it’s really better for me to drive to Chicago in my car than it would be to grab an empty seat on a plane that’s already going that way. In that sense, isn’t it like the bus? Yes, the bus pollutes more than my car, but it has to drive the same route every day whether I get on or not. I understand that by buying a plane ticket, I am generating demand that the airlines then supply, in theory. They might add more routes and so forth. But that seems more like an issue for a regular traveler, not for a once-a-decade plane trip to Europe. Please help me get my head around this!

Beverly B.
Louisville, Ky.

Dearest Beverly,

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Thank you. Two little old brains are better than one, so together perhaps we can puzzle through the good points you raise. Those of you who have just joined our travel smackdown, please visit the prior trains vs. cars and cars vs. planes question and the lively discussion that followed my thrilling use of math.

Give buses a transporting chance.

Have you heard that airlines are starting to charge fees for luggage — not to mention using lighter-weight beverage carts, seats, and silverware — to keep down fuel costs? From a fuel perspective, each additional passenger is like a giant walk-on suitcase. A heavier plane requires more energy to fly, hence it burns more fuel and emits more greenhouse gases than a lighter plane. For that reason, estimates of greenhouse-gas emissions for air travel are always accompanied by qualifiers about numbers of passengers. So weight is one reason not to jump on a plane.

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Another reason is that — as you rightly suspected — the trips we take encourage those airlines to keep flying. Supply and demand affects air carriers much the same way it impacts the bus business. We can easily imagine how this works with the latter. Say we’re making last-minute plans to travel from Louisville to Chicago for a windy weekend. We check the bus schedule, discover there are two buses per day, and buy tickets for one of the routes. We board the bus, and see that on a Friday it’s practically deserted.

What would we logically conclude from our lonely ride with more-than-ample seat choices and full access to the bathroom? That few people choose to travel from Louisville to Chicago this way. And it would be no surprise the next year to find that the bus company had slashed the number of trips on that route. Likewise, if our bus had been sold out, we wouldn’t be surprised if the services increased.

Bus companies — whether they’re offering intercity bus service (between cities) or local routes in town — will supply vehicles to meet demand. That’s logical, right? It doesn’t matter whether you buy tickets far in advance or at the last minute; for intercity buses it doesn’t matter whether you commute daily or hop on once a fortnight. Transit companies have figured out the typical load and try to serve that load. We all generally accept this rationale, and there’s no reason not to extend it to the airline industry.

Just thinking of yourself as a surprise airline client doesn’t discount you as a demand generator, either. In order to snag a decent profit, carriers have to take into account the frequently flying businesswoman and the once-yearly international vacationer. You, the individual traveler, matter to the airlines. And what the world needs now is fewer flying travelers and fewer planes in the air. So it’s truly better not to fly if you can avoid it.

Buses, on the other hand, need your support. Out of all our road transportation options, intercity buses are the best choice vis-à-vis global warming. Within cities, meanwhile, buses are often the only form of public transport (one that’s relatively kind to planet and pocketbook). Both types of bus services will be easy to expand if demand was to grow, and demand must grow. Though, like me, you may wish we could all ride affordable and frequent trains, the infrastructure for instantly expanding rail travel is simply not here. We need to increase our use of mass transit. Support buses by riding them when you can and voting to fund them when asked. And enjoy your trip to Chicago.


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