Anyway, it's not true. Air in the cabin is bled off the engines, from the early stage of the compressor, then pressurized and heated. It's not one cabinful of air that was in it from the ground endlessly recirculated.
QI also told the world that the Internet uses GPS to route packets (tho' some devices may use GPS for its clock signal, packets don't know geographically where they are).
a show with a team of good researchers, they can on occasion be wrong (and have corrected themselves for mistakes in previous shows in the past), but they won't put a fact into a show without getting good sources for it
So while they may be wrong in this instance, the fact that they are a comedy show isn't reason enough to think so.
You don't have to pay for air during flight - it comes from the outside air and is free, it's not canisters or something.
Result: Each air change costs around .62 of a gallon of gas (assuming perfect efficiency). Or around $2.50 - let's call it $10 to account for inefficiency. In contrast it costs around $10,000 per hour (not including salary) to fly a large plane.
Saying they don't circulate air to save money is ridiculous.
You can work this out my looking at an an airlines profits, and how many flights they did a year.
By my calculations a smaller 70 passenger plane would use around 1/5 the energy per air change, and they typically fly for only an hour or two. So for an air change every half an hour it would cost them around $4 per flight (and that's assuming low efficiency). So $100 profit is still possible (although I have to say that that's amazing low, but I'll take your word for it).
In this case, airlines are a business designed not to have runaway profit. The unions are very powerful. They know how much money the airline is making a demand large percentages of it. They leave a nominal profit for key investors but shareholders as a whole are regularly left out. In fact, if you look at the entire history of commercial flight, the industry is break-even.
That's not a fluke. If costs were higher, unions would get a smaller cut. If costs were lower, unions would take more.
Philip Greenspun has some great writing on this, as well as the old, shortlived but fantastic Enplaned blog.
Yes, you can increase the pressure. But then your flying tube in a low pressure environment may explode
Or it'll suffer a bigger expansion/contraction with every cycle and hence less cycles or metal fatigue and failure at 37000feet (passenger won't ask for a refund as they will be unable to do)
So the "cabin altitude" is really a balance between mechanical resistance and people not passing out (though this may be a good idea with some passengers)
I don't have a source and am too lazy to find one, but it was stated on QI which is a show with a team of good researchers, they can on occasion be wrong (and have corrected themselves for mistakes in previous shows in the past), but they won't put a fact into a show without getting good sources for it, so if they say that air gets recycled less now than when smoking was allowed, I believe them.
Sorry - it's my fault for not giving more background on Mr. Smith - Patrick Smith has been a Delta Air Lines pilot for about 10 years, written two books on airlines, before that flying cargo, and I've met him more than once, so I'll trust him and the other pilots I've met when they tell me how their airplanes work.
Here's more of his articles on the subject: http://www.salon.com/2009/09/25/askthepilot335/ http://www.askthepilot.com/questions-and-answers/#cX-q9
and another article here: http://airlinesafety.com/articles/FSFCabinAir.htm
I'll allow that it's certainly possible that manufacturers have tweaked the circulation post-smoking, but even if so, it wasn't done with some nefarious intent or to the detriment of passengers. The air we breathe (as I'm about to get on a flight) is incredibly clean, cleaner than in my office.
Your sources are all (I think?) about the fact that the way they deal with air is good, and you may well be right that it's cleaner than in your office. That doesn't mean that it's not less clean than when smoking was allowed - it may well be that in order to get rid of the smell of smoke they needed to clean the air way more than technically necessary, and that therefore after the smoking ban it could be lowered without being "some nefarious intent".
"Stephen Well, the question is . . . It was almost certainly a bad idea, erm . . . It was a lousy idea, in fact, 'cause when smoking was allowed, the cabin air was completely replaced with fresh air every three minutes, and now, the airlines save money . . . they save up to 6% of their fuel bills by using a mixture of fresh and recycled air--
Julia And SARS.
Peter Ohh.
Stephen --yeah . . . using under half the amount of fresh air needed for comfort; increasing the amount of carbon dioxide in the cabin; causing dizziness, and nausea, and allowing viruses to thrive. Passengers think that, because they can't smell smoke, the air is fresher. This is not so. Apart from anything else, it has dramatically increased the number of air rage incidents. One of the earliest reported incidents of air rage involved a passenger in first class, probably trying to take his mind, erm, off cigarettes, by drinking too much, and he was refused another drink, and so he decided to lodge his displeasure, and shat on top of the food trolley. "
While Patrick Smith may not be an air conditioning expert, as a pilot he's required to know how the AC systems work and how to operate them, and if there was a widespread modification to AC systems or pilot procedures after the smoking ban, I'd expect him to know about it and mention it in the article.