<http://schema.org/description>
"A pressurized airplane cabin is important because the air pressure at altitude is much lower than the air pressure at sea level. Just how does a pressurized airplane cabin work, though? Learn more about pressurized cabins in this article."^^<http://www.w3.org/2001/XMLSchema#string>
<http://science.howstuffworks.com/transport/flight/modern/question15.htm>