11 Things You Probably Didn’t Know About Airplanes

Planes are designed to be struck by lightning—and they regularly are hit. It’s estimated lightning strikes each aircraft once a year—or once per every 1,000 hours of flight time. Yet, lighting hasn’t brought down a plane since 1963, due to careful engineering that lets the electric charge of a lightning bolt run through the plane and out of it, typically without causing damage to the plane.

The FAA says there is no safest seat on the plane, though a TIME study of plane accidents found that the middle seats in the back of the plane had the lowest fatality rate in a crash. Their research revealed that, during plane crashes, “the seats in the back third of the aircraft had a 32 percent fatality rate, compared with 39 percent in the middle third and 38 percent in the front third.”

However, there are so many variables at play that it’s impossible to know where to sit to survive a crash. Oh, and plane crashes are incredibly rare.

On long-haul flights, cabin crew can work 16-hour days. To help combat fatigue, some planes, like the Boeing 777 and 787 Dreamliners, are outfitted with tiny bedrooms where the flight crew can get a little shut-eye. The bedrooms are typically accessed via a hidden staircase that leads up to a small, low-ceilinged room with 6 to 10 beds, a bathroom, and sometimes in-flight entertainment.

The tires on an airplane are designed to withstand incredible weight loads (38 tons!) and can hit the ground at 170 miles per hour more than 500 times before ever needing to get a retread. Additionally, airplane tires are inflated to 200 psi, which is about six times the pressure used in a car tire. If an airplane does need new tires, ground crew simply jack up the plane like you would a car.

When a plane lands at night, cabin crews will dim the interior lights. Why? In the unlikely event that the plane landing goes badly and passengers need to evacuate, their eyes will already be adjusted to the darkness. As pilot Chris Cooke explained to T+L: “Imagine being in an unfamiliar bright room filled with obstacles when someone turns off the lights and asks you to exit quickly.”

Similarly, flight attendants have passengers raise their window shades during landing, so they can see outside in an emergency and assess if one side of the plane is better for an evacuation.

The idea of an engine giving out mid-flight sounds frightening, but every commercial airplane can safely fly with just one engine. Operating with half the engine power can make a plane less fuel-efficient and may reduce its range, but planes are designed and tested for such situations, as Popular Mechanics reported. Any plane scheduled on a long-distance route, especially those that fly over oceans or through uninhabited areas like the Arctic, must be certified by the Federal Aviation Administration (FAA) for Extended-range Twin Operations (ETOPS), which is basically how long it can fly with one engine. The Boeing Dreamliner is certified for ETOPS-330, which means it can fly for 330 minutes (that’s five and a half hours) with just one engine.

In fact, most airplanes can fly for a surprisingly long distance with no engine at all, thanks to something called glide ratio. Due to careful aeronautical engineering, a Boeing 747 can glide for two miles for every 1,000 feet they are above the ground, which is usually more than enough time to get everyone safely to the ground.

The FAA banned smoking on planes years ago, but eagle-eyed passengers know that airplane lavatories still have ashtrays in them. As Business Insider reported, the reason is that airlines—and the people who design planes—figure that despite the no-smoking policy and myriad no-smoking signs prominently posted on the plane, at some point a smoker will decide to light up a cigarette on the plane. The hope is that if someone violates the smoking policy, they will do so in the relatively confined space of the bathroom and dispose of the cigarette butt in a safe place—the ashtray, not a trash can where it could theoretically cause a fire. If you do smoke in the bathroom, expect a massive fine.

It’s to regulate cabin pressure.  Most airplane windows are made up of three panels of acrylic. The exterior window works as you would expect—keeping the elements out and maintaining cabin pressure. In the unlikely event that something happens to the exterior pane, the second pane acts as a fail-safe option. The tiny hole in the interior window is there to regulate air pressure so the middle pane remains intact and uncompromised until it is called into duty.

Airplane food has a bad reputation, but the food itself isn’t entirely to blame—the real fault lies with the plane. A 2015 Cornell University study, reported by Time, found that the environment inside an airplane actually alters the way food and drink tastes—sweet items tasted less sweet, while salty flavors were heightened. The dry recycled air inside the plane cabin doesn’t help either as low humidity can further dull taste and smell making everything in a plane seem bland. According to a 2010 study from the Fraunhofer Institute for Building Physics in Germany, it’s about 30 percent more difficult to detect sweet and salty tastes when you’re up in the air. Next time you fly, skip the meal, and maybe try a glass of tomato juice instead.

The safety instructions on most flight include how to use the oxygen masks that are deployed when the plane experiences a sudden loss in cabin pressure. However, one that thing that the flight attendants don’t tell you is that oxygen masks only have about 15-minutes worth of oxygen. That sounds like a frighteningly short amount of time, but in reality that should be more than sufficient. Remember, oxygen masks drop when the airplane cabin loses pressure, which means the plane is also losing altitude. According to Gizmodo, a pilot will respond to that situation by donning an oxygen mask and moving the plane to an altitude below 10,000 feet, where passengers can simply breathe normally, no extra oxygen required. That rapid descent usually takes way less than 15 minutes, meaning those oxygen masks have more than enough air to protect passengers.

Those white lines that planes leave in the sky are simply trails of condensation, hence their technical name of “contrails.” Plane engines release water vapor as part of the combustion process. When that hot water vapor is pumped out of the exhaust and hits the cooler air of the upper atmosphere, it creates those puffy white lines in the sky. It’s basically the same reaction as when you see your breath when it’s cold outside.