Interesting. I guess that is why I do not enjoy being on planes. And perhaps part of the reason people get sick on them during the winter.
Most of the big modern commercial aircraft don't use bleed air for cabin pressurization anymore but instead use electric compressors. They don't send any hot air outside of the engine pod as it is considered safer and more efficient to simply run generators from the engine shaft horsepower and send HVAC out to the cabin pressure and AC/Heating systems. Back in the 707 days you would notice a hydrocarbon smell in the cabin air right at engine startup when a puff of half-burned fuel came out of the the bleed air systems and some made it into the cabin. I hate the modern fighter O2 generation systems because there is no tank and you can't crawl into the cockpit with a hangover on Saturday morning and close the canopy and go onto 100% oxygen like the old days. I remember putting the switch on 100% and putting the hose down my shirt on very hot days working on Phantoms. It was a not a dangerous act and could not cause a fire like Apollo because the oxygen was not under great pressure and there was no mask so it mixed down with ambient atmosphere. Best hangover cure on the planet.
I read recently that the main reason people get sick on planes is not because of the air but the because of the surfaces.
The air is trapped, its a pressure vessel that is kept pressurized with the same air in the cabin for the whole flight. Any germs from sneezing etc are just kept in the cabin. If it wasn't for the extremely low humidity and moderate pressurization (8,000 ft equivalent pressure generally) it would be even worse. That is why they really freak if someone with TB has been on a flight because it is so likely that everyone breathed it.
Actually that's largely incorrect, the B52 hasn't flown a combat sorties since ~06 while B1's have been deployed in support of OIF/OEF since Oct 2001. It's actually made a very successful transition into conventional roles such as CAS, long range strike and stand-off weapons delivery. The nature of the fight since its inception has certainly changed but for the most part the aircraft has undoubtedly been able to keep pace and relevancy in the current nature of the fight.
True. The B-52s did some great work in Afghanistan flying out of Guam and Diego Garcia but its been the B-1B that has done the heavy lifting since about 2006. I love the video of the B-1B dropping 48 JDAMs.
I love the line from Donald Sutherland in Kelly's Heroes as a tank commander: "I just ride them, I don't know what makes 'em work".
I remember that line. In my defense, if there is any, most if not all corporate jets still use engine bleed air.