the decrease in air pressure associated with flying combined with the foreign presence of a 6cc mass of a substance that is not as dense as the surrounding tissues could lead that 6cc to swell by 100x it's original size thereby pushing the surrounding tissue out and possibly leading to the explosion of your ass or leg, wherever you may have injected the substance, covering all the passengers within a 10 foot range of your coach seat with blood, skin, and bone and rupturing your femoral artery so that you bleed out within a matter of minutes if a tourniquet is not properly applied within seconds.