Surely, most of you heard stories that back in the golden age of railroad travel going to the toilet was really an interesting experience. You could go to the toilet, use it and flush it, and then your attention was attracted by the epic scene of the toilet getting opened and the toilet’s contents getting dumped right onto the tracks. That was the main reason why all the railroads had signs that says: „Please do not flush the toilet while the train is standing in the station. Thank you!“ Probably, these kinds of stories that were passed by generations through years led to most interesting theories about the aircraft's toilets and feces. Furthermore, an additional boost to these theories were signs in aircraft's toilet such as: „Do not flush while seated!“
Is it really correct that aircrafts get rid of their waste while flying sky high? Luckily, back in the 1975., James Kemper invented the vacuum toilet that is being installed in aircrafts since 1982. This patent solved the problem how to get rid of unwanted materials without causing additional issues. In order to kill the odors and disinfect the bowl he added a nonstick bowl that uses a blue substance known as Skykem to replace water and a powerful vacuum suction that lefts almost nothing behind. The main reason why this vacuum system works is because it is constantly subject to suction pressure as there is a pipe leading to the outer skin of the airplane.
Every time when you flush the toilet, a trapdoor in the toilet opens and Skykem fills the bowl. Next, you hear a loud roar that may seem like you feces are just being launched in the atmosphere, but the truth is that is sound is basically the sound of your feces being pulled by the vacuum toilet in specific, separated waste tanks. This sound is so powerful because the velocity of this suction is even greater than the velocity of a speeding car. There is no way that these waste tanks can be emptied by the pilot during the flight nor that they are designed to be emptied up in the sky. After the aircraft lands, special service trucks approach and attach a hose to the aircraft, and consequently suck out the waste into the trucks. At the end, these trucks transfer all of these feces and liquids to the place designated for these kinds of purposes.
We would like to note that there were cases when people did report that they were hit by the feces and blue liquid or blue ice that came straight from the aircraft. But, in most cases these feces were product of other fliers such as birds. Occasionally there were cases when the aircraft had damaged their tanks filled up with Skykem liquid, but luckily without additional undesirable materials in it.
All in all, you can be pretty sure that if something falls on the top of your head, shoulder or any other part of your body, it is almost impossible that these are human feces dropping out of the aircraft, but luckily bird poop landed up on you!