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Comment by btcindivist | Hacker News Reader

Depends on how many. Flying airplanes is around 1-2% of our total CO2 footprint. Of course, for an individual, doing 1 intercontinental flight with a full plane is equivalent to months if not a year of driving a car to work every day, but in total, not many people fly.

Depending on the efficiency of the rocket and the reduced number of people doing this, the numbers shouldn't be that much higher.

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That's not really the case. Per passenger mile commercial aircraft get ~70MPG with longer flights tending to have better fuel economy. The trend is really interesting: http://www.slate.com/content/dam/slate/articles/business/the...

So, they are actually very efficient transportation for long trips. Absolute worst case flying around the world is 24,901 mi which uses the same fuel per person as a 35 MPG car commuting 26 miles each way for one year.

PS: You can double check this by considering ~1/3 of the cost of a seat as being spent on fuel.

What is not the case? 1-2% of total CO2 footprint? That flying a full plane is equivalent to months if not a year of driving a nontrivial distance every day?

I'm not saying cars are more efficient. It's just that the distance travelled is huge when one uses an airplane.

Many people use more fuel in a month getting to and from work than a round trip NYC to London flight. It comes down to both distance and fuel economy with some commuters putting in over 1000 miles a week. The range for commuting fuel uses vs transatlantic flight is much wider than 10x months to year.

Longer flights have better fuel economy only in short range regimes where the BFR is definitely not a consideration.

https://commons.m.wikimedia.org/wiki/File:777-224_fuel_burn-...

Fuel economy improves at first due to reduced overhead of taxiing, takeoff, and ascent, but as you go farther the fuel consumption increases due to the need to actually carry the fuel.

Aircraft choice plays a role here. Airlines tend to use more efficient aircraft for longer flights.

Airlines use longer range aircrafts for longer flights. That should be obvious, shouldn't it?

Efficiency is one way to increase range. Wingtip devices can reduce drag by inhibiting vortex formation, however they increase weight so there is a minimum flight distance before they are a net gain. https://en.wikipedia.org/wiki/Wingtip_device

There is a tradeoff of needing carry more fuel over a portion of the flight, but the aircraft also spends a higher percentage of it's fuel on flying vs taxiing etc.

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