You probably may not have noticed this but if you’re an experienced traveler or just an attentive person, you may have noticed that cabin crew always keep their arms folded behind their backs when greeting passengers and when walking the aircraft cabin. When doing so, they also don’t appear to check that seat belts are fastened or that passengers’ phones are turned off.
It’s really quite simple: before take-off, the cabin crew needs to count the number of passengers onboard. This takes place either as they enter or when the passengers have all sat down. The cabin crew uses a special counter to do this:
The cabin crew keeps their arms behind their backs when doing the counting in order to not attract too much attention to themselves.