In the name of passenger comfort and above all, to avoid panic on board airplanes, airlines hide some details of their day-to-day operations. They are not secrets per se, as they are data described in manuals and aeronautical regulations, but they are information that companies in the sector prefer to keep without much disclosure.
Did you know, for example, that there are axes hidden in the cabin of airplanes? Or, that flight attendants receive self-defense training to deal with eventual aggressive passengers? These are details that may seem controversial, but they are fundamental to keeping the flights safe.