Many passengers think very little about flight attendants. They are just there, you think, to push a heavy cart down the aisle to dispense to you some drinks or your meal. But there's a lot more to the job than you think. A flight attendant is not your server or waiter. They are not paid to help you stuff your luggage into the overhead bin. In fact, the flight attendant's primary responsibility is to keep the plane safe, and to ensure that the passengers are also safe. You may think you know everything that goes on a plane and so you ignore their requests to remove your laptop from your tray table. Why? Because you think nothing bad will happen if you don't listen to them.

But the unthinkable can happen if you don't obey. For example, during severe turbulence, your laptop may go flying off the tray table and hit someone in the head. That's just one thing, the flight attendant's ability to stop something that may harm passengers before it actually happens. But while you can ask flight attendants about that, there are a lot of things that they can't divulge so as not to scare or frighten passengers or make them worried. Or because it's protocol. Did you know that only flight attendants have the power to give you a free upgrade? And that they only do that for a reason they can't admit? Or how about that flight attendants size you up if they think you can help them out if there's an emergency on the plane?

Luckily for you, you don’t have to fly completely blind, as we’ve gathered a collection of 25 things flight attendants have to keep from passengers. We've raided their tricks of the trade and unveiled to you the reasons behind the secrets they won't share with you.

25 Your Laptop Can Hit Someone

We always hate it when flight attendants tell us to turn off our smartphones and store all electronics like iPads and laptops under the seat upon takeoff and landing. But most of us don't know the reason besides the fact that we have to turn off our cell phones to avoid interference with the pilot's radio signals. Well, here's what they won't tell you so as not to scare you.

Your laptop might just hit someone near your seat.

Seriously. Electronics are potential projectiles that could cause serious damage if there's severe turbulence, according to The Daily Meal. Everything will be flying off tray tables, so if you don't listen to your flight attendant, you may just get hit in the head by someone's Kindle.

24 The Tray Table Is The Dirtiest Thing On The Plane

What flight attendants keep from passengers is the fact that the tray table is perhaps the dirtiest thing on the plane, even dirtier than the bathroom. It's full of germs and bacteria because passengers do all sorts of things on the tray table, such as putting their feet up on them, laying their heads on them and changing their babies on them.

Travelmath did the figures and tray tables were found to have an average of "2,155 colony-forming units (CFUs) per square inch".

Travelmath also warned you that if any food you eat falls on the tray table, do not ingest it. So bring some sanitary wipes with you.

23 They Know How To Build A Stack for safety

First, what's a stack? Well, that's when flight attendants take a potentially dangerous device they found on the plane and stuff it somewhere in the aircraft to prevent it from blowing a hole in the airplane.

Second, where do they stuff the device? According to the Electronic Urban Report, that's something flight attendants can't divulge and is top secret.

This is something that attendants have to keep from passengers so that if a device was actually on a plane, passengers won't know what the attendants are doing. If they did, there would be mass chaos.

22 Being A Flight Attendant Is A Health Risk

Another thing that flight attendants have to keep from passengers is the fact that their jobs are dangerous to their health. They have to keep this private so that passengers don't get worried that they too have their health at risk while flying.

Business Insider Australia put together the 27 jobs that are most damaging to your health, and flight attendants ranked high at #2.

Their top three health risks were exposure to contaminants, exposure to disease and infections and exposure to minor burns, cuts, bites, or stings.

21 Flight Attendants Do More Than Serve Drinks

There are a lot of things that can happen at 37,000 feet in the air. And who is taking care of a problem? The flight attendants are because they have been trained to protect the flight deck at all costs. They put their life on the line while you're snoring in your sleep, and they handle a situation with the utmost discretion.

As a flight attendant told Stuff,

"We're truly hard-trained safety experts on a plane to save your life, not just to serve you a tomato juice. The training is inexplicable, like childbirth. You can't understand how hard it is until you experience it".

For example, if your laptop catches on fire in the overhead bin, it's the flight attendant's responsibility to put out the fire.

20 That Tray Table Isn't The Only Dirtiest Thing On The Plane

Flight attendants keep from passengers how dirty the seats are. If they did, no one would want to sit down. The seats aren't cleaned between flights and are only brushed over to get out stuff like food crumbs. Thus, the seats contain a lot of germs. Your best bet to keep you harm free is to wear pants. Even though it's like 98 degrees outside, you shouldn't ever wear shorts on a plane.

As a flight attendant told Reader's Digest, planes are dirty "[B]ecause they’re not cleaned as often. All the normal things we usually deal with, we don’t normally think about when we sit down in shorts in a seat that’s been used by many other people."

19 Chimes Are A Method Of Communication Between The Crew And The Pilots

When we fly, we always hear a chime or a series of charms. What are they intended for? Well, technically, this is something flight attendants have to keep from passengers. But we have the truth. Chimes are methods of communication between the flight attendants and the pilots. According to Reader's Digest, one chime from the pilot warns the attendants that there is turbulence ahead.

When the plane is approaching 10,000 feet, you'll hear two chimes. But when you hear three or more chimes, this means danger. The pilot is telling attendants of impending extremely rough air or something worse. The three chimes also mean that flight attendants are trying to tell the pilots that there is a very sick passenger on board who needs immediate help.

18 Flight Attendants Aren't Supposed To Help You With Your Luggage

Flight attendants don't lead the glamorous life. For one thing, they get paid by the hour, which, according to Business Insider is anywhere between $18 to $20 per hour. For another, they get paid only for flight hours. That means they don't get paid during boarding or deplaning. According to Uvisor, what flight attendants keep from passengers is the fact that they aren't required to help you put your heavy bags into the overhead bin.

If they get injured doing this, flight attendants' unions won't cover them.

So if you see a flight attendant helping a passenger with their luggage, know that they are doing this out of kindness. And if you see a flight attendant not helping you out, now you know the reason.

17 The Water Supply Is Unfit To Drink

Flight attendants cringe when they see passengers make soup using the airline water, or order coffee or tea. But they will keep from you that the airplane's supply of water is not clean and that their tanks are old and contain bacteria. It's just not something a passenger wants to hear if they order coffee.

According to Business Insider, flight attendants don't ever drink the water or things made from water like ice cubes.

Because coffee is hot, the water used can kill some germs. But flight attendants don't take their chances. They go out of the way to buy coffee at the airport terminal and always drink bottled water.

16 The Real Reason Why Flight Attendants Greet You

There's a reason why flight attendants greet you when you board the plane. They are actually checking you out, according to the Huffington Post. If you look built and fit, they are filing this fact in their mind in case they need you to assist them with security issues or an emergency evacuation.

If you look sketchy and do not make eye contact with you, they will keep an eye on you.

If you look nervous, they will later talk to you to see if you have a fear of flying and will do their best to comfort you. Sizing you up is one major thing that flight attendants have to keep from passengers.

15 A Flight Attendant Is Responsible For an Unaccompanied Minor

Certain school-aged children can travel on an airplane without their guardian or adult companion. Technically, they are flying alone, but much to the dismay of flight attendants, your unaccompanied minor (UM) is their responsibility once the aircraft door is closed. So if the plane crashes, it's the flight attendants who have to locate the UM and make sure they are safe.

According to Flight Attendant Joe, flight attendants urge parents to equip their UM with many distractions so they don't go wild on the flight.

That means a bag full of books and games, downloaded movies on an iPad or laptop, the foods they like, and anything else that can keep them occupied during the entire flight.

14 Flight Attendants Have To Wear A Watch

Flight Attendants are required to have two watches while on duty. It's not simply to keep track of time. The watches are needed during emergencies. To help them stay on top of their duties in difficult scenarios, flight attendants assess time to pinpoint the exact period when something unthinkable happens in order to report to officials later.

The need for two watches is for backup, according to The Telegraph. If the flight attendants misplace the watch they are wearing, they have easy access to another that they store in their carry-on.

13 The Bathroom Door Can Actually Be Opened On The Outside

Flight attendants keep from passengers that the lavatory door can be opened from the outside. That's a secret so that passengers don't try to get in for some possible reason while a fellow passenger is inside.

But the real purpose is if someone gets locked inside and can't get out.

All the flight attendant has to do is just lift the "lavatory" sign and slide the knob into the unlocked position, according to The Thrillest. Also, as a backup, flight attendants have their own keys to get into the bathrooms.

12 Can Texting Really Cause A Plane To Malfunction?

After the aircraft door closes before ascending, the flight attendants will ask you to switch your iPhone or other mobile phones to airplane mode or to just power down the device. And of course we listen because there's that seemingly undisputed fact that we'll bring down the plane if we're texting.

But as Travel + Leisure revealed, this is like an old wives tale and  "[T]here has never been a case of people using their phones to cause a plane to crash". Still, electronic device interference can affect aircraft systems, although that's very rare.

11 Why The Plane Lights Go Dim

Passengers know that when the lights go dim on a plane, it means that you are steadily traveling for the long haul or are in the final moments of descent. During night flights, the lights stay dim during landings and takeoffs.

So as not to worry passengers, flight attendants keep from passengers that dim lights are not for your comfort, but rather so you have some night vision.

As The Telegraph revealed, the low lighting is a preparation for an evacuation, should the need arise. Dim lights mean your eyes are adjusted to the darkness so you'll be able to see better once outside the plane.

10 Flight Attendants Do Get To Sleep On The Plane

Flight attendants often have a 14-hour or more workday. It's an exhausting job, filling requests from passengers, helping them out, and ensuring the general safety of the plane. So flight attendants do get some shut-eye when the plane is traveling and stabilized.

According to Insider, some planes have secret passageways that let staff sleep in peace, like the Boeing 777 and 787 planes.

The crew won't let you know where these places are so that passengers don't try to break into these areas. A door near the front of the plane or a door posing as an overhead bin is where these private places are kept.

9 The Planes Are Only Deep Cleaned Once A Month

Flight attendants have to keep this fact from passengers because they won't like what they hear. It's the fact that airplanes only get a proper cleaning about once a month. But for a deep clean, that only happens when the planes are brought back to the hangar.

Think about all those many hours up in the air and how dirt, debris, germs and bacteria are piling up on each flight. If you see a fellow passenger disinfecting their tray tables or pushing away garbage on the floor before their seat, you should do the same.

8 It's Not Just You Who Are Annoyed By A Crying Baby

Seeing a baby on board always frightens passengers. They hope the baby or child will be asleep during most of the flight or remain calm and quiet. Because the last thing you want to hear while you're on a plane is a crying baby or child. It just disturbs the passengers who are trying to relax or go to sleep.

You want to find the parent of the crying baby and give them a lecture about minding their child. Well, what flight attendants definitely will not let on is they too are disturbed by a crying baby and that they too have a wish to tell off the parent or guardian, according to Express UK.

7 That Pillow And Blanket You Requested Are Full Of Germs

A flight attendant will gladly give you a blanket or pillow if you request them. What they keep from you is that those items of comfort are gross and aren't washed or changed after every flight, according to the Huffington Post.

In fact, those blankets and pillows are re-used repeatedly by other passengers.

And if you think that if a flight attendant hands you those items in clear plastic bags, know that the only thing clean is that bag. Instead, the blanket is refolded nicely and the pillow is just fluffed by the crew to look brand new, as Finance Twitter admitted.

6 So Are The Earphones

If you're going to watch an in-flight movie, you'll want some headphones. But do not whatsoever take one of the earphones that the flight attendants pass out for free, as The Daily Meal suggested. Just like the tray table, they are not clean. That's because they aren't new.

Flight attendants will never tell you that they re-use the headphones and to make them look new, they put them into a sealable plastic bag. Nobody actually washes or cleans them. The extra pressure on the aircraft and all the germs can literally make you sick. So next time, bring your own headphones!