When we take the plane, the main questions we ask ourselves often concern safety, comfort or food. However, some people have always wondered how toilet waste ends.
Blue liquid and vacuum suction
On the Quora platform two years ago, a user asked the following question: “Is it true that when you use the toilet on an aircraft, the waste is simply evacuated outside the device and fall into the sky?” ». In his answer, the author Laurent Richard first recalled that on a long-haul flight 747, each passenger visits the toilet 2.4 times on average. In total, there is a question of 870 liters of waste per person.
He believed that to treat this enormous amount of waste, only an engineering miracle could be up to par. In planes, since 1982, the toilets do not work with a classic siphon and water, but with a non -stick bowl using a blue material: Skykem. This substance thus replaces water and a very powerful vacuum suction, and allows you to leave no trace or almost in the bowl.
When we pump the flush, a hatch opens and the blue liquid enters the bowl, disinfecting the latter. The noise that happens can then surprise people not used, but it is not that of a hatch opening on the outside. Indeed, this noise is none other than that of vacuum aspiration. The functioning of this type of toilet is described precisely in an article published on the specialized platform L’Arrerriser (see diagram below).
Credits: the aircraft manufacturer
Are there risks of falling the contents of the toilet?
The toilet waste on the device is stored in a tank and it, accessible from the outside only, is emptied once the aircraft is on the ground. In other words, pilots absolutely do not have access to it and cannot empty it in full flight. At the end of the chain, the tank emptying precedes its cleaning using a disinfectant product.
The risk of falling such waste since planes is extremely low today. On the other hand, the problem was quite common in the 1960s and 1970s. It must be said that at the time, the toilet pipes were not secure enough, so that leaks occurred from time to time. Thus, the urine and the excrement mixed with the Skykem found themselves outside the rear landing train. Obviously frozen, the whole took the appearance of a “blue ice”.
Going down, the plane allowed the ice to start melting, and therefore the block to fall. Several cases of fall have been identified, but the best known remains that of 1971, when a block of blue ice has literally gathered the roof of a house located in London. As for the voluntary drop in toilet waste, this has indeed existed in the past. In the 1930s at the start of civil aviation, the devices were actually equipped with toilets open to the outside.
