The cabin is pressurized to 7 or 8 thousand feet rather than sea level. I believe that gas expands at higher altitude and compressses below sea level, therefore it would stand to reason that at higher altitudes you will have more gas in your colon, hence the consequences of passing gas. Whenever I fly on a flight more than 4 or 5 hours I experience this gaseous distension. \hope this helps! Cheers.