Are you someone who spends the entire length of a flight sweaty-palmed, gripping on to the armrests? Do crazy thoughts zip through your head; Will the door break open? Can the plane land on water? Is that the sound of the wings snapping off? If this is you, stop reading now.

For some travellers, the science and facts speak for themselves. After all, statistically speaking, flying on a commercial airliner is the safest form of transport there is, according to the US National Safety Council.

For others, flying is a means to an end and certainly not something worth over-thinking. Then there are the passengers who struggle to trust their lives in the hands of technology and pilots because, ultimately, being trapped in a tin can at 30,000 ft with nowhere to go if things go wrong, is an all-consuming fear.

Whichever category of flyer you come under, air travel is a fact of life, but even the most confident passenger might be unnerved by a few of the little-known facts about airplanes - and those who pilot them - that airlines would rather keep under wraps.

We’ve compiled 20 concerning facts that will make you think twice before setting foot aboard a plane, and five facts about pilots you’d probably rather not know. Happy flying.

25 25. These 11 Minutes Are The Most Dangerous

Okay, so dangerous might be an exaggeration, but research has shown that if an accident does occur, it's far more likely to happen within the first three minutes of a flight or in the last eight minutes before landing.

These 11 minutes are responsible for 80% of all fatal accidents, according to an in-depth analysis by Boeing, which studied worldwide commercial flights from 2007 to 2016.

So if you’re someone who sits down, kicks your shoes off and gets an eye mask on before the plane is even in the air, you might want to reconsider staying awake and alert.

24 24. Airplane Air Is As Dry The Sahara, Quite Literally

You may have noticed your skin, nose, eyes and mouth dry out when flying and that’s because the pressurised air in the cabin is kept below bone-dry 20% humidity, which is just about the average humidity of the Sahara Desert.

This is chiefly a by-product of cruising at high-altitudes, where moisture content is somewhere between low and nonexistent, and while humidifying a cabin would seem like a simple and sensible solution, it’s avoided because it would require large quantities of water, which is heavy and expensive to carry.

All of that dry air saps the water from your body to the tune of about eight ounces an hour, which, if you do the maths, is roughly a two-litre bottle during a 10-hour long-haul flight. Stay hydrated.

23 23. Planes Regularly Get Struck By Lightning

It’s a simple fact, airplanes get struck by lightning frequently. It is estimated that an individual jetliner is struck about once every two years, on average. Fortunately, they're built to handle it.

Lightning typically strikes a sharp edge of a plane, like a wingtip or nose, and the current exits via the tail. An aircraft’s fuselage acts as a Faraday cage, protecting the interior from any voltage, and electrical parts around components like electronic flight equipment and fuel tanks are carefully grounded.

Rare though they may be, there have been a few fatal incidents involving lightning strikes, however. In January 2014, a light aircraft owned by Intan Angkasa Air was hit by lightning and crashed, which was instantly fatal for all four people on board. In 2010, it was the same fate for two others when a Boeing 737-700 from Bogota was struck by lightning and split into three pieces as it landed at San Andres island in the Caribbean.

Another serious case, resulting in 81 fatalities, happened in 1963, when a lightning strike over Maryland caused a wing to explode on a Boeing 707 flown by Pan Am.

But seriously, lightning is nothing to worry about.

22 22. That Little Hole In The Window Might Save Your Life

If you’re a fan of a window seat, you may have noticed a tiny hole in the window. These are "bleed" or "breather" holes, and they help keep you safe by allowing pressure to be balanced out between the cabin and gap between window panes.

Air pressure is dangerously low at a cruising altitude of 35,000 feet, so a plane's cabin must be pressurised to be much greater than the outside air. However, this puts a huge strain on the aircraft. Enter the tiny breather holes, which regulate pressure. Plus, they release moisture and minimise the frost or condensation blocking your view, which is great for your Instagram pics.

21 21. Some Airplanes Are Required To Carry An Axe Onboard

Although an axe is expressly forbidden as carry-on items for passengers, for super obvious reasons, axes were commonly carried as part of an aircraft's firefighting equipment to enable flight crew to break through panels and sidewalls in case of an electrical fire.

Only aircraft above a certain capacity were required to carry an axe, although, due to new regulations, most carriers have replaced their axes with crowbars which are insulated to protect against shock.

20 20. Plane Exhausts Are More Fatal  Than Plane Crashes

Forget crashes, there’s something way scarier about air travel: You’re more likely to die from exposure to toxic pollutants in plane exhaust than in a plane crash, according to a 2010 MIT study.

Fewer than 1,000 people perish in plane crashes each year, but around 10,000 a year can be attributable to toxic pollutants emitted by jet engines, researchers say.

Airplane exhaust, like car exhaust, contains a variety of air pollutants, including sulfur dioxide and nitrogen oxides. Many of these particles of pollution are tiny, about a hundred-millionths of an inch wide, or smaller than the width of a human hair, but the fact they’re so small means they can become wedged deep in the lung and possibly enter the bloodstream. Good to know, huh?

19 19. You Have Only 90 Seconds To Escape A Burning Plane

As tempting as it is to zone out during the in-flight safety briefing because you’ve heard it all a million times before, it might just be worth pay attention to.

Did you know that the FAA requires that all aircraft be capable of being evacuated in just 90 seconds, as a minute-and-a-half is the amount of time it can take for a fire to spread throughout the plane. As scary as that sounds, imagine how much worse it would be if you didn’t have a clue where you’re nearest emergency exit was.

Pay attention, know where they are and if you want to go that extra mile, up your odds by wearing cotton or non-synthetic clothes, which will make you less flammable.

18 18. The Tail Is The Safest Place To Be During A Crash

If you’ve ever wondered where the best seat to improve your chances of survival, in the unlikely event of an emergency, might be, it’s in the tail.

Again, plane crashes are totally rare, but a 2007 study by Popular Mechanics looked at 36 years of NTSB crash data and found the back of the plane gave passengers the best chance for survival. And if that’s not persuasive enough, it’s also the most strategically advantageous for befriending your flight attendant and getting free stuff. Double whammy.

17 17. Your Plane Might Be Older Than You

According to 'Airfare Watchdog', an airline expert, the skies are full of old airplanes including the Boeing 717s and the primitive versions of the 757, 767 and 737.

Commercial aircraft are built to last more or less indefinitely, which is one of the reasons why they’re so expensive. In fact, it’s common for a jet to remain in service for 25 years or more.

According to - a website which monitors most major airlines - of the world’s 30 largest carriers (based on passenger numbers), Delta Airlines has the most mature planes with an average age of 17 years. Air Canada and United Airlines are reckoned to have the second and third oldest fleets, with an average age of 14.2 and 14.1 years respectively.

16 16. Sit More Than Five Rows From An Exit And You’re In Trouble

If - and we know, it’s a big if - a crash happens, you really, really want to be sat within five rows of an exit. Statistical analyses of plane crashes have shown that passengers who sit farther than five rows from an exit have greatly reduced chances of successfully evacuating during an emergency.

If you’re not sat within the coveted five-seat radius, hope is not lost. Another way to increase your chances of getting off a plane after a crash is to count the rows between your seat and the nearest exit once you've boarded the plane. If visibility is reduced by smoke, you'll still be able to find your way out.

15 15. There's More Risk Of Turbulence Now Than Ever Before

If you’re a frequent flyer and you’ve noticed air travel getting bumpier, it’s not your imagination. Turbulence is on the rise due to increasing levels of carbon dioxide in the air.

In fact, scientists have predicted that the amount of moderate to extreme turbulence experienced on transatlantic flights could increase by between 10 and 40 percent by mid-century, and it’s all thanks to global warming. So, really, it’s all our fault. Buckle up.

14 14. You Might Be Flying With An Engine Down - And Not Even Know It

Planes can fly with one engine, and land with none, which is pretty cool and disconcerting, all at the same time. Commercial jets are designed to fly with only one operable engine for extensive periods of time, and can glide their way to the ground with no engine power at all, which is fab news if your plane breaks down mid-flight.

In truth, if an engine does stop working, it’s unlikely you’ll even know. Pilots know exactly what information to share with passengers and what will cause outright panic. They’ll probably just keep the information to themselves. It's better for everyone that way.

13 13. Stay Calm: Grab Handles On The Emergency Exit

Next time you enter an aircraft take a look at the grab handles at about shoulder height just inside the cabin. They're a safety measure for cabin crew and a “calming measure” for passengers.

When it comes to evacuating a plane, passengers can, understandably, be a bit panicky. Providing a handle to hold onto slows down the escape to an orderly queue for the emergency slides.

They also give cabin crew something to hang on to while they supervise and assist in an emergency, otherwise they might get shoved outside the cabin in the rush to escape.

12 12. Let’s Hope You Never Have to Use Them: Yellow Wing Hooks

Wings are designed to be as aerodynamic as possible, so it may confuse passengers to notice two small yellow bumps on them. These tiny features are a crucial safety aspect of many commercial aircraft because, in the event of a water landing, these small hooks help passengers safely exit the plane.

If cabin crew must facilitate an emergency exit over the wing, they will pull out ropes from safety lockers above the emergency exit, secure one end of the rope in the door frame while the other end of the rope is fed onto the wing and through the small yellow hooks.

Passengers can use this rope to steady themselves on the wing as they make their way toward the inflatable exit slide. These hooks can also double up as rudimentary handholds.

11 11. What Happens If A Door Opens Mid-Flight?

In short, nothing good. Should someone actually manage to open the door of a large passenger aircraft at high altitude, the cabin would lose pressure - extremely rapidly - and chaos would ensue.

Anyone standing near the exit would be ejected into the sky, the cabin temperature would quickly plummet to frostbite-inducing levels, and the plane itself might even begin to break apart.

Fortunately, it is simply impossible to open a plane door during a flight - cabin pressure won’t allow it. Almost all aircraft exits open inward and, like a bath plug, an aircraft door is fixed in place by the interior pressure.

If you’re wondering why skydivers or military personnel can regularly leap from aircraft doors, it is because those planes are not pressurised.

10 10. Airlines Often Skimp On Fuel

Airlines don’t want to carry any more fuel than they can get away with because more fuel, means more weight and increased operating costs.

The FAA regulates the amount of fuel that must be on board for any given flight and mandates it carry a reserve capacity, which is usually just enough to land at an alternate field if there is a problem at the destination airport, but not much more.

In Europe, however, a report by Spanish safety investigators revealed that some airlines are reportedly flying with less-than-recommended fuel levels in an effort to save money. It’s best not to think about it.

9 9. Your Plane Is A Flying Petri Dish

With planes flying on tighter schedules than ever before, the rush to turn flights around in mere moments means there's often no time for cleaning.

The FAA has nothing to say about how often and how thoroughly planes are cleaned, so the airlines are in charge. Singapore Airlines - the ninth cleanest airline in the world, according to Skytrax - gives its planes a hearty scrub down every 30 days. Delta, on the other hand, only deep cleans every 90 to 100 days, and this hit-and-miss approach to hygiene has consequences.

Since cold and influenza viruses can live for days on surfaces, planes can become hotbeds for germs. One study found that 60 percent of tray tables tested harboured the "superbug" MRSA, and according to an investigation by the Wall Street Journal, airplane blankets are only washed every 5 to 30 days. Pack antibacterial wipes and hope for the best.

8 8. Yes, There’s An Ash Tray. No, You Can’t Smoke

Smoking on planes was banned in 1990, finally allowing all flyers to breathe easy. So why are airlines still building planes with built-in ashtrays?

The fact is, some people will simply do it anyway, and should it happen, the Federal Aviation Administration figures it’s better to provide these reckless rule breakers with the means to properly extinguish their cigarette rather than risk its disposal in a trash bin, ultimately jeopardising the entire aircraft and occupants.

7 7. Travelling With A Child On Your Lap Can Be Fatal

You wouldn't dream of driving with your child sitting in your lap instead of a car seat, so why would you do it on a flight?

It might be cheaper to travel with an infant on your lap, instead of spending extra money on a separate seat, but according to the FAA, the safest place for your child on an airplane is in a government-approved child safety restraint system (CRS) or device, not on your lap.

Kids can easily fly out of a parent's arms during severe turbulence or a crash, hurting not only the child but other passengers as well. Survivable accidents can become fatal for unrestrained infants.

6 6. There’s A Whole City In The Sky

It may not readily be apparent, but at any given moment, there is the population of a decent-sized city in the skies at all times. Data aviation company FlightAware claims that there are, on average, 9,728 planes in the air at any moment, carrying 1,270,406 passengers. That’s roughly the population of Cyprus, in the sky, right now. How is it not total chaos up there?

Well, there are very strict guidelines governed by the International Civil Aviation Organisation (ICAO) and respective national authorities, which dictate how close planes can fly from each other.

Aircraft should be kept 1,000 feet or 300 metres apart vertically. Horizontally, if aircraft are following the same path - or track - they should be 15 nautical miles apart. Under other circumstances, planes should be at least five nautical miles apart, a distance allowed to drop to three when the aircraft enters the jurisdiction of an airport’s tower controller; on final approaches into airports (within 10 nautical miles) this is allowed to drop to 2.5. Simple.