The world of commercial aviation is still a complex and mysterious place.
After all, there's nothing normal about being flung across the sky at 500 mph in a pressurized metal tube that's strapped to jet engines — all while you sip on a drink and watch a movie.
There are many are odd things about flying that most passengers don't know.
Here are some things airline workers won't tell you.
1. The oxygen masks don't give you much time to breathe.
The yellow emergency oxygen mask is an essential part of every in-flight safety briefing and all classic airplane disaster movies. "If the aircraft cabin losses pressure, the panel above your seat containing oxygen masks will open automatically," the safety instructions say. "While remaining in your seat, quickly reach for the nearest mask and pull down firmly to start the flow of oxygen."
Ever wonder what happens when you pull down on the mask? In most cases, the action triggers chemical oxygen generators located above each seat. These generators supply supplemental oxygen in times the pressurized environment inside the cabin doesn't provide enough breathable air. Most airliners are pressurized at an altitude of 5,000 to 8,000 feet.
However, these generators are only meant to supply temporary oxygen — usually between 14 and 20 minutes. This is designed to provide enough oxygen in the time it takes the aircraft to descend to an altitude (roughly 12,000 feet or below) with breathable air.
2. It's possible for the plane to run out of fuel.
On August 24, 2001, Air Transat Flight 236 lost power in both its Rolls-Royce turbofan engines while flying over the Atlantic Ocean. The Airbus A330-200 with 301 passengers and crew on board had been on a flight from Toronto, Canada, to Lisbon, Portugal, when a fuel leak drained the jet's fuel tanks.
The flight's pilots managed to glide the 193-foot-long airliner nearly 100 miles to the nearest airport in the Azores Islands. The flight made it to safety with the help of a small emergency windmill called a ram air turbine, or RAT for short.
The RAT uses energy from air rushing by the aircraft to generate electricity — giving the pilots access to important flight instruments and control surfaces of the plane.
Although the the RAT isn't able to actually power the aircraft, it does give pilots much of the most important information they need to fly the plane.
The RAT is located in different areas of the plane depending on the model and the manufacturer of the aircraft. For instance, the RAT is located in the belly of the fuselage of the Boeing 787 pictured above. On the other hand, the turbine is stored in a compartment under right wing on Airbus A340s.
Click below for photos of the world's most frustrating airports:
3. The bathroom door isn't really locked when you're inside.
Airplane lavatories are small, cramped and the location of choice for a mid-flight rendezvous with a significant other. However, they are not as private as you may think. Most lavatories can be accessed externally even when they have been locked.
On some aircraft, unlocking the door is as simple as lifting up the "lavatory" sign and sliding over the toggle switch located underneath the cover.
Lavatory doors can be locked and unlocked from the outside for a multitude of reason. It allows flight attendants quick access to locked lavatories in case of emergencies. In other instances, it allows the cabin crew to restrict access to bathrooms during takeoff and landing.
So if you are thinking about a mid-flight dalliance, don't. Those locked doors all not all that locked.
4. The tray tables are ridiculously filthy.
As much as airlines make an effort to keep their planes clean, large fleets and short turnaround times simply don't allow them clean every surface. Which leads us to the obvious question: What are the dirtiest places on the plane?
According to a study conducted by microbiologists hired by Travelmath, seatback tray tables are a hotspot for bacteria.
According to the study, microbiologists found an average of 2,155 colony-forming units a square inch on tray tables collected from four different planes. In contrast, the study found an average of "just" 265 CFU/sq.in. on the lavatory flush button.
5. Some planes are equipped with a "corpse cupboard."
With billions of people hopping on and off flights every year, it is inevitable that people die while flying. Although crews will do their best to divert to the nearest available airport, sometimes it's not possible.
Once the passenger is determined to have died, the cabin crew will first work to store the body in a respectful manner and, if possible, away from other passengers. If there is room, the body will likely be placed in unoccupied rows of seats or in first class where there is more empty space. However, on crowded flights, there may not be room to relocate the deceased, at which point the corpse would be covered up and strapped into a seat.
Singapore Airlines, which operates a fleet of more than 100 wide-body long-haul airliners, has been known to equip some of its planes with special "corpse cupboards" to store the deceased on long flights.