Have you ever noticed the whirl of announcements that come from the loudspeaker just before take off and landing on a plane?
From the confusing 'arm doors and cross check' message over the PA system to the captain telling staff to disarm the doors after landing, you could be forgiven for thinking the cabin crew are speaking in a secret code.
However now there's no need to sit in wonderment as the flurry of activity happens on your flight because Qantas flight attendants have revealed everything about their mid-air cryptic behaviour.
According to Escape, when the announcement comes on that the cabin crew should 'arm doors and cross check', it actually means that the door is ready to use if the plane should find itself in an emergency situation.
Apparently, when crew hear this over the loudspeaker, they know that the inflatable slide is ready to deploy and inflate if the attendants move a special level to open the door.
Before landing, you'll often hear the announcement: 'prepare the cabin for landing'.
This gives flight attendants the warning that the plane is descending and they should check that all passengers have their seatbelt fastened, have their tray table up and that their window blinds are open.
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Back in September, a flight attendant told Tech Insider that there is a pretty serious reason as to why your slumber is interrupted before you land - and it's not to let you look at the views below.
"If there's an emergency, we have to be able to look out the window to assess outside conditions," one flight attendant told Tech Insider.
"If there is debris, fire, or water blocking the window, we won't use that exit and will direct people elsewhere.
"It may seem like a small thing, but in an emergency, every second counts. You don't want to have to fiddle with a window shade when you're trying to safely evacuate a plane in 90 seconds."
With only 90 seconds to evacuate in case of an emergency, passengers are often able to alert cabin crew to something wrong on the outside if their blinds are open, meaning there's more chance of a successful evacuation in such a short space of time.
As for all the 'boing' sounds you hear on the plane throughout the flight, that's so the crew can all communicate with each other as they move around.
It also goes off when someone presses the service bell, when the seatbelt sign is switched on and as a warning to the crew that there is turbulence ahead.