It's technically impossible to die on a flight. Although flight crews are trained in basic first aid and some are even qualified to perform resuscitation, most flights do not have any staff members on board who are qualified to declare a time of death.
 
Airplane lavatories can unlock from the outside. You can actually unlock the lavatory from the outside via an external lock mechanism, which is usually hidden beneath the "no smoking" sign on the door, according to LifeHacker.
 
Pilots acknowledge that there are several safety rules aboard aircrafts that don’t make a whole lot of sense, including exactly when the crew has to be seated with their belts on.
 
There’s a secret spot for sleeping! Flying for more than 12 hours at a stretch is obviously going to lead to some exhaustion, but some travelers may be uncomfortable with the thought of their pilot taking a nap
 
Those emergency oxygen masks deliver a supply that lasts only 15 minutes!  What isn't usually shared with the passengers is that the flowing oxygen will last between just 12 and 15 minutes.
 
The chimes that sound mid-flight are a secret code! flight attendants use the chimes to signal a host of things to one another, from the snack supply running low to an increase in turbulence.
 
The headsets and earbuds are not new! It's a dirty secret in the airline industry that headsets and earbuds are recycled after every flight—even the ones that come in plastic pouches you have to open.
 
Flight attendants are paid once the plane doors close! In the case of a few airlines, cabin crew are only paid for their 'flight hours', meaning their pay is based on when the flight leaves and arrives at each gate.
 
Your lost luggage gets auctioned off! It’s the ultimate travel disaster – you arrive at your destination airport to find your bag was lost in transit and is nowhere to be seen. 
 
Babies born in US airspace become US citizens! This has only happened on a few occasions and it’s a real grey area. The newborn's citizenship depends on several factors.
 
A plane can't take off if you're in the loo! Legally, a plane can’t take off if someone is in the toilet because take-off and landing are the two of the most at-risk moments on the plane.
 
Pilots and co-pilots eat different meals! It very rarely happens, but to prevent the chances of both getting food poisoning, many pilots and co-pilots opt to eat different in-flight meals.
 
Empty 'ghost flights' fly all the time! When you see a plane pass above you in the sky, there's a fair chance it has no passengers. A new report by The Guardian reveals that 5,000 completely empty 'ghost flights' have passed through UK airports since 2019
 
Your boarding pass contains a lot of secret, and incredibly personal information. Reading the codes on your boarding pass gets more complicated. The most interesting and secret part of your ticket is the six-digit alphanumeric segment of coded text called the PNR or Passenger Name Reference.
 
Pilots have a secret code they use to communicate with air traffic control, this code is known as the "squawk code", and it's used to identify the plane to air traffic control and other aircraft in the area.
 
Many airplanes have secret compartments or "hideaways" that are used for storing emergency equipment or for hiding from hijackers.
 
The cabin pressure in an airplane is kept at a lower level than the pressure at sea level. The cabin pressure is kept at the equivalent of about 6,000 to 8,000 feet above sea level. 
 
Pilots sometimes fly with a hidden dead man's switch that automatically takes control of the plane in case of an emergency. This switch, which is typically located in the cockpit, can be activated by the pilot if they become incapacitated or unable to fly the plane.