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Why planes can't fly when it's too cold or too hot? And why airplanes wait on the runway before takeoff? What's the future of airplanes? And will the planes of the future take us straight to space? Find out right now!
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00:00When it's too cold outside, airplanes often get delayed, or in extreme cases, even cancelled altogether.
00:07First of all, if it snows heavily, such conditions drastically decrease visibility, making it unsafe to taxi and take off.
00:16During a blizzard, flight control may command the aircraft to stay on the ground and wait until the snowstorm subsides.
00:24Ice on the runway is another reason.
00:26An airplane's landing gear are nothing like a car's wheels, and they can't be equipped with studs to avoid skidding.
00:33But even if they were, a plane needs to develop speeds on the ground that are much higher than on
00:38an average road to take off successfully.
00:41If the runway is slippery with ice, the airplane can slide off it easily.
00:46Things like this actually happened in the past.
00:49For example, in January 2014, the JFK airport in New York was shut down after a plane skidded off the
00:56runway and into the snow.
00:58Luckily, no one was injured, but the airport staff had to dig the aircraft out of the snow, and even
01:04the local police joined the efforts.
01:07Same story with landing, which is even trickier in freezing conditions, because a plane is in much less of a
01:13controlled environment and traveling at even greater speeds.
01:16What's more, while an airplane that's about to take off and skidding will probably get into an open area and
01:23stop there, one that's about to land could end up crashing into the airport's infrastructure.
01:28Needless to say, that's way more dangerous for everyone.
01:32Freezing weather conditions can also cause frost and ice sheets to build up on the plane itself.
01:37Airplanes are carefully engineered, and any tampering with their structure may cause huge trouble.
01:43As experienced pilots say, even a thin crust of ice over the wings of a plane can mess with their
01:49delicate design and destroy lift.
01:52Planes can be de-iced, though.
01:54The airport staff usually spray them with a special solution that doesn't let the ice build up on the aircraft's
01:59skin.
02:00But back to the runway.
02:02If it's covered with ice, there's little you can do.
02:05Unless the sun is shining, the chances of safely removing the ice from the pavement are almost zero.
02:11There's also a chance of damaging the pavement, making potholes, which can result in safety concerns for both takeoff and
02:18landing.
02:19Imagine driving over a pothole in a car at full speed.
02:22Pretty unpleasant.
02:24And now multiply it by about a thousand, because a plane is much heavier than a car, and don't forget
02:29that the landing gear is not exactly there for driving.
02:33Jet fuel and the equipment that pumps it can freeze, too, if the temperature is too low.
02:38The fuel freezes at negative 40 degrees Fahrenheit, but that can only happen on the ground before takeoff.
02:45At a cruising altitude, temperatures may drop as low as negative 70 degrees Fahrenheit, but since the liquid is inside
02:52the plane and burning down steadily, it's much warmer there.
02:56On the ground, though, nothing stops the fuel from turning into ice.
03:00If that happens, no flights are available, obviously.
03:04Same goes for the pumping equipment.
03:06Even if the fuel is still liquid, the pump may cover with ice, and just stop delivering the fuel into
03:12the plane's tanks.
03:13In the worst-case scenario, it might even break down, leading to expensive repairs and prolonged delays in flights.
03:20Finally, ground crews have to do a lot of work before takeoff or landing, and they're all human after all,
03:26so they can't bear the freezing cold for too long.
03:29This issue is often resolved by tag-teaming.
03:32One group of workers goes out in the field to do the job, while the other is waiting for them
03:37in a shelter.
03:38After 20 minutes or so, the first group returns to warm up, and the second one takes up the job
03:44where the first one left it.
03:45Although it's efficient, it still slows down the operations a lot, so that might also cause delays.
03:52But, despite all the trouble freezing weather can cause, it's actually more beneficial for a plane than extreme heat.
03:59Cold air is denser than hot, so planes gain more lift and stay truer while in the air.
04:05They're more easily controlled in flight, too.
04:08Air molecules are slower and closer together, creating a steady flow of air around the wings and cockpit.
04:15At high altitudes, the air naturally becomes thinner, as the air molecules spread out and become more scarce.
04:21That's exactly why planes can't get to the upper layers of the atmosphere.
04:25There's just not enough air there to create sufficient lift.
04:28The same happens when it's too hot down on the ground, though.
04:32Air molecules get faster and spread out, meaning the plane's wings don't have as much air to push off and
04:38get into the flight mode.
04:39To take off in extreme heat, a plane has to move much faster to generate enough air resistance and lift.
04:47But, to move faster, the plane needs its engines to work better, and that's also impossible when it's too hot.
04:53As the air gets thinner, the amount of oxygen decreases, too.
04:57And jet engines use oxygen in the atmosphere for combustion.
05:01When they lack this crucial element, they can't convert enough energy into thrust, meaning slower acceleration and worse energy output
05:10overall.
05:11So, the problem is that the plane has to have a longer runway distance to build up enough speed and
05:17lift to take off.
05:19But it can't, because its engines are not working to the best of their ability.
05:23This usually doesn't cause trouble, but only up to a point.
05:27When the temperatures on the ground level reaches about 120 degrees Fahrenheit, some flights can get cancelled, because it's simply
05:35dangerous for them to try and take off.
05:38Other planes are more heat-resistant and powerful, but that also depends on the heat.
05:43Some aircraft even have to reduce their weight by removing part of their fuel, cargo, or even passengers when it's
05:50too hot.
05:51Lighter load means better acceleration before takeoff, and it doesn't help to avoid cancellations.
05:57But it also means planes aren't working to their full capacity.
06:01The average cruising altitude for an airplane is about 35,000 feet.
06:06They don't technically need to be so high up, but that altitude gives the best speed and efficiency.
06:12Air gets thinner at higher altitudes, which means less wind resistance, but less lift.
06:17For most commercial aircraft, the area between 30,000 and 40,000 feet is the sweet spot where the two
06:24factors balance out.
06:26You probably still aren't using a laptop from 1999, and your computer isn't flying at close to the speed of
06:33sound.
06:34Fortunately, planes have a much longer lifespan than computers.
06:38There are airliners from the early 1970s that are still just fine.
06:42They might not be able to keep up in terms of speed and fuel efficiency, but older planes are no
06:49less safe than their modern counterparts.
06:52Contrails, those white trails airplanes leave behind them at high altitudes, are easily mistaken for engine exhaust, but most are
07:00nothing more than water vapor.
07:02During a flight, moisture in the air collects in the engines before being vented with the exhaust.
07:08The hot, wet air leaving the engines mixes with the cool, dry air found at high altitudes, resulting in long,
07:15thin lines of vapor.
07:17Humidity determines when contrails form and how long they remain visible.
07:22Ever notice the numbers on the end of a runway?
07:25They're actually used to show the pilot which direction the plane is facing.
07:29For example, the number 36 is short for a heading of 360 degrees or due north.
07:36Along with numbers, the letters R and L indicate if the nearest runway is to the right or left.
07:44The lights on the tips of a plane's wings are called position lights or navigation lights, and they're used during
07:50times of reduced visibility.
07:52They help planes to see each other in the dark, and can also tell pilots what direction an aircraft is
07:58traveling.
07:58The red light marks the tip of the left wing, while the green light is on the right.
08:03The third light is white and found on or near the tail.
08:08It might seem odd that the flight crew cares whether your window shades are up or down.
08:13The main reason is so that the passenger's eyes can adjust to the outside light.
08:17Mostly, it's just a matter of getting people on and off quickly.
08:21But in an emergency, the last thing they want is people stopping to blink before they evacuate the plane.
08:41Passengers always board from the left side.
08:44That's because the captain sits on the left side of the airplane cabin, so it's easier for him to align
08:50the plane with the terminal jet bridge from that side.
08:53Also, the aircraft is fueled and loaded with baggage on the right side.
08:57With passengers boarding from the left side, the crew can do their job undisturbed.
09:03If your priority is to get out of the plane as fast as possible once you arrive, pick an aisle
09:08seat near the front of the plane.
09:10If you want to have the most comfortable flight, pick a seat in the middle of the plane, because the
09:15turbulence is less noticeable there.
09:18An even better option in terms of comfort would be those seats by the emergency exit.
09:23They have more legroom, and you can stretch.
09:25If you want the safest seats on the plane, your best option is the back of it.
09:30Once you're seated, take your time to spot the nearest emergency exits.
09:35Count the number of rows between your seat and an emergency exit.
09:38It can save your life in case you have to leave the plane quickly.
09:41You'll manage to find the exit easily, even if everything around is dark or if you're blinded.
09:47You'll find it just by touching the seats and passing the number of rows you counted in advance.
09:52Boarding completed. Time to get ready for takeoff.
09:56Cabin crew are walking down the aisles to make sure all passengers are following their instructions.
10:01Okay, everyone has their seatbelts fastened and window blinds open.
10:05There's no one in the bathroom, and the runway is all clear.
10:08Why aren't we still moving? We can go!
10:12Turns out, the aircraft must wait for a while. It's all about safety.
10:16When a plane takes off, it activates two powerful forces.
10:20One is jet wash.
10:22A fast-moving gas so strong, it can easily flip a car.
10:26So no one can be near the plane.
10:28Another force is wingtip vortices that are the result of the wind generating the plane lift.
10:35These powerful rotating forces go from both wings and stay in the air for about three minutes after an aircraft
10:41takes off.
10:42If another plane flies into the air while the wingtip vortices are still there, the pilot will lose the roll
10:49control over the aircraft.
10:51The plane will flip over and crash.
10:52So, no plane is allowed to take off without waiting for at least three minutes after the previous one leaves.
11:00Back to the pilot's cabin.
11:02There are two people there, the pilot and the co-pilot.
11:05In case something happens to the first pilot, the co-pilot can take over.
11:09Both pilots eat different food to reduce the risk of them both feeling unwell.
11:14While the first pilot controls and adjusts the autopilot, the second one monitors the controls or communicates with the control
11:22tower.
11:23Also, there are checklists for safety standards to be satisfied at different stages of the route.
11:28So, while the captain is focused on the route, the co-pilot can complete the checklist and make sure that
11:34everything's going according to the plan.
11:37Flying is costly.
11:39So not only the passengers, but the airline as well want to make the flight as fast and short as
11:44possible.
11:45The shortest way is always a straight line.
11:49Still, aircraft routes look like an arc.
11:51It's because the Earth isn't flat like we see it on a map.
11:54It's a sphere.
11:56So, these lines only appear like arcs when we project them on a map.
12:00In reality, they're pretty much straight.
12:03Every airline and every plane wants to fly this most efficient way.
12:08But there are hundreds of planes flying every day, often in the same direction.
12:12So the air highway is pretty busy.
12:15The route data of every plane is pre-planned and is uploaded to the system.
12:20There are several of those so that the pilot has options if something goes wrong or if weather conditions change.
12:27The pilot can set up the right mode and autopilot can control the airplane within its uploaded route.
12:33Keep up the altitude, speed, and direction.
12:36The pilots, meanwhile, keep an eye on the autopilot and focus on other tasks like navigating, planning, and communicating with
12:44air traffic control.
12:45On the ground, air traffic is managed by dispatchers, who watch over planes and make sure they don't get too
12:52close to each other.
12:52The air traffic is especially heavy in some places.
12:56So, when an aircraft enters a busy zone, it has to follow a very specific route.
13:01There are also specified points called fixed navigational aids, or, shortly, nav-aids.
13:09Those are devices on the ground that send radio signals in the sky that an aircraft can pick up on.
13:15There are also waypoints, which are geographical points on Earth.
13:19They're loaded into the GPS system, and an aircraft has to follow them.
13:23So, basically, the whole route is flying from one waypoint to another all the way to the destination place.
13:30Time to start the descent.
13:31You can see the plane's altitude on the control panel.
13:34The pilots know the plane's speed, so they can calculate at what distance to destination to start their descent.
13:41If the altitude is 27,000 feet, and the speed is 300 nautical miles per hour, the first number, divided
13:48by the second, gives us 90 nautical miles.
13:51This is the point they have to start the descent to maintain the descent path.
13:56There are also a couple of other things to consider, such as the wind speed and direction, or uneven speed
14:03drop.
14:03To descend, pilots have to get approval from the controller.
14:07Sometimes, due to traffic, they don't get it right away.
14:10So, they just keep moving forward without descending,
14:14therefore shifting away from the descending profile and land when the approval is given.
14:20Takeoff and landing are the most crucial and dangerous phases of any flight.
14:24That's because the pilot has less time and space to react to any occurring problems.
14:30In the air, even if both engines stop working, a plane won't just start falling.
14:35Instead, it'll begin to glide through the sky, losing about one mile of altitude every ten of them going forward.
14:42So, the pilot will have about eight minutes to react and find a safe place to land.
14:48If an engine fails during takeoff or landing, the pilots will only have seconds to decide if they should still
14:54take off and deal with the problem in the air or cancel the flight.
14:59Even if something happens, canceling the flight isn't always an option.
15:03When the plane reaches the speed of 100 miles per hour, you can't possibly stop it before the runway ends.
15:10And getting off the runway isn't good, to say the least.
15:14To ensure everyone's safety, the rules at these stages of the flight are especially strict.
15:20You should turn on the airplane mode on your devices to make sure that the signals that devices transmit
15:25don't interfere with the plane's electronic systems and don't block the radio's frequency.
15:30You've probably heard that clicking sound a speaker makes right before your cell phone gets a call, if it's right
15:36next to the speaker.
15:37These sounds are what the pilot might hear instead of the instructions while communicating with air traffic control.
15:44Even a one-second interference can cause a lot of confusion.
15:48Just some certain types of cell phones can cause this problem, and if it's a combination of factors,
15:53the cell phone type, how far away it is from the cabin, and how many cell phones aren't in airplane
15:59mode.
16:00The cabin crew can't find out which of the passengers didn't put their phone into airplane mode,
16:05but the pilots will always know when many people didn't do it.
16:09You should keep your window blind open during takeoff and landing for safety reasons as well.
16:14This way, your eyes get used to the light or the darkness outside.
16:18In case of an emergency, during these risky stages of the flight,
16:22people who are comfortable with the natural light will react and evacuate faster,
16:27which is crucially important when every second matters.
16:30For the very same reason, the lights are dimmed in the airplane.
16:34This way, the light will be closest to the light outside the aircraft.
16:38Another reason is that if the window blinds are open,
16:42people from the outside can see what's going on in the plane.
16:45For example, they can see if there's a fire inside and where exactly it is.
16:50This way, they can plan the evacuation better.
16:53They ask you to fold up your table and put up your seat in the upright position
16:58to ensure that in case of an emergency, there will be no obstacles in the way.
17:02Everyone should be able to leave the plane as fast as possible.
17:06The passengers aren't allowed to use the bathroom during takeoff and landing
17:10because there's no seatbelt, no safe escape route with no obstacles,
17:14and it's not safe overall.
17:16A person can get trapped there during evacuation.
17:19The pilot isn't even allowed to take off or land while someone is in the bathroom.
17:24And looks like we're ready for landing.
17:27Welcome to New York.
17:30You're standing on the roof of a control tower at the airport.
17:34You see a huge plane coming in for a landing.
17:36It's whizzing over your head, but all you hear is the wind whistling.
17:40The first sound the plane makes is the scraping of the tires against the asphalt.
17:44That's because this giant airplane runs on electricity.
17:48It doesn't need to burn tons of fuel.
17:50And it doesn't attract the attention of passers-by with its noise as it flies over the city.
17:55But engineers predict that all-electric airplanes won't appear for another couple of decades.
18:00For now, the Dreamliner 787, which can carry 310 passengers and emits no pollution,
18:06remains a sweet dream for designers.
18:09Let's jump back in time to 140 years ago.
18:12In 1883, a French aviation enthusiast made the first-ever electric-powered flight.
18:18He installed an electric engine on the dirigible.
18:21The problem was that the engine weighed as much as a big motorcycle.
18:25So, the dirigible couldn't fly long distances and lift many passengers.
18:29Okay, back to our time.
18:31The problem of heavy engines and batteries remains unsolved.
18:35One pound of regular airplane fuel contains 60 times more energy than one pound of even the
18:40most advanced battery.
18:41So, we'd have to increase the airplane's tank by 60 times and fill it with batteries.
18:46But now, the plane is much heavier and it can barely take off.
18:50So, we have to remove a lot of necessary things from the plane,
18:53like several rows of seats, toilets, and all the drinks and snacks.
18:57So, the plane loses some weight.
18:59And now, shove more batteries into all the empty places.
19:02The plane can take off now, but it can't land.
19:06The plane is designed to take off with a full tank and land with almost nothing.
19:11Otherwise, its landing gear just can't take the load and breaks when it touches the ground.
19:15So, if the plane needs to make an emergency landing right after takeoff,
19:20it'll have to circle over the airport until it's burned enough fuel.
19:23It's allowed to land only when it reaches a certain weight.
19:27But, in the case of batteries, the weight of the plane doesn't change during the flight.
19:31So, designers had to find another solution.
19:34Let's drive this little single-engine airplane into a hangar
19:37and take out the old fuel-burning engine, exhaust system, and fuel tank.
19:41Replace them with an electric engine, which is much smaller and lighter.
19:44Pack all free spaces with batteries.
19:46The weight of the final version of the plane should remain exactly the same as the original plane.
19:50So, now, it can take off and fly without any problems.
19:54But it can only do that for short distances.
19:57And that's a huge advantage of electric planes.
19:59About half of all flights in the world are under 500 miles.
20:03There's a lot of flights over distances like that,
20:06from New York to Washington, D.C., or from Detroit to Toronto.
20:09It's less than 200 miles.
20:11And there are huge passenger planes flying on those flights.
20:14They take off, gain altitude, and then immediately land.
20:17Using these gas burners at such short distances is like putting a huge freight elevator in a two-story house.
20:24It's not profitable, and it doesn't make sense.
20:26All the conventional airplanes in the world emit about 1 billion tons of CO2 a year.
20:32So, we can reduce the amount of damage to the environment by half by using electric planes.
20:37Many designers are trying to convert some planes into electric ones.
20:41For example, the Cessna 208B e-caravan.
20:45The normally nine-seat passenger plane now uses an electric engine.
20:49As of 2020, it's undergoing certification.
20:52This means that every bolt and wire on the plane is tested for safety.
20:56This process could take years.
20:58ES-19 is an all-electric four-engine airplane.
21:02The aluminum hull makes it extremely light.
21:05Although the price per unit is about $8.8 million, its maintenance costs are 90% less than regular airplanes.
21:12And electric power for the plane itself is 50% to 75% cheaper than standard fuel.
21:18It'll be able to cover distances of about 220 miles.
21:22It's great for traveling in Europe or between remote islands.
21:25And it can use runways no longer than 2,500 feet.
21:28Given that these planes are practically silent, airports could be built close to city centers.
21:33This would cut travel time almost in half.
21:36Aviation Alice has taken another step into the future.
21:40This nine-seat plane is made almost entirely of composite materials and powered by three engines.
21:46The inverted boat shape and V-shaped tail make its aerodynamics perfect.
21:50It has the length of a school bus and the wingspan as wide as a basketball court.
21:55Its maximum takeoff weight is like two SUVs.
21:5960% of that weight is batteries.
22:01This gives it the ability to fly distances of about 620 miles.
22:05That's more than the distance from New York to Detroit.
22:08The best thing about the Aviation Alice is the economy.
22:11Flying nine passengers and two crew at top speed will cost about $200 an hour.
22:17For conventional planes of the same class, like Cessna and Beechcraft, that number would be about five times bigger.
22:23The problem of short-range flights can be solved by a network of abandoned airports in the United States.
22:29There are about 2,000 of them and 5,000 public airports.
22:33Each of them can be equipped with a charging station, just like a gas station.
22:37A half hour at a charging station for Alice would be equal to one hour of flying in the air.
22:41So while passengers are getting off and on and their luggage is being loaded, the plane can build up enough
22:47energy to fly.
22:48So, small planes are good as an air taxi or private jet.
22:52But you need at least 20 Aviation Alice planes to replace a full-fledged Boeing 737 with 180 passengers.
22:59The price for one electric bird is $4 million.
23:02So that's $80 million versus $100 million for one Boeing.
23:06So, the Alice wins again.
23:10Zunum Aero tried to build an electric plane that could carry 50 passengers.
23:14The company first went for a 12-seat ZA-10 airplane.
23:17It was a hybrid, powered by the combined work of traditional and electric engines.
23:22Engineers relied on evolving batteries and predicted that their plane would be able to travel 1,000 miles.
23:28So, it could fly from L.A. to Seattle on a single charge.
23:32And it would only have to cost $500,000 more than Alice.
23:36The big 50-seat plane should have worked on the same principle.
23:39But the company lost funding before they could introduce the finished plane.
23:43Maybe we can create an all-electric plane that doesn't have any moving parts at all.
23:47It would use ionic wind.
23:50MIT engineers created a lightweight model of an airplane with a wingspan of about 16 feet and no engine.
23:57There's a metal structure similar to a fence between the wings of the plane.
24:00A battery powers this structure with negatively charged electricity of 40,000 volts.
24:05There's the same structure in the back of the wing, which was positively charged.
24:09When the structure is powered, its front end captures negatively charged electrons from the air, just like a magnet.
24:16The electrons then fly toward the positively charged structure at the back.
24:19As the ions move, they collide with air molecules millions of times.
24:24This creates thrust, just like a regular airplane.
24:27And as it moves, it keeps charging the particles in the air and pushing them back.
24:31Engineers from MIT did about 10 test flights.
24:35Their plane was able to fly almost 200 feet on ion thrust.
24:39But their model airplane only weighed 5 pounds, and it flew without a pilot.
24:43The lightest manned airplane in the world, the BD-5J, weighs 7 times more.
24:49So it should have giant wings to fit this metal structure for ion thrust.
24:53And the voltage in that structure would have to be much higher to create enough thrust to let the plane
24:58take off.
24:59So this technology needs many years to develop and refine before it can be tested on real-scale airplanes.
25:05Right now, one of the most reliable and economical electric engine schemes is to work together with traditional propellers or
25:12turbines.
25:13An airplane can use an electric motor for a quick and quiet takeoff.
25:16It'll gain altitude and leave the airspace of a densely populated city.
25:21Then, it'll start the main engines, which run on fuel combustion.
25:24This will allow the plane to reach high speed and fly a long distance.
25:29During this time, the plane's batteries will be charged by the generator powered by the main engine.
25:34When it's time to land, the main engines stop, and the plane lands completely silently with the electric engine.
25:40So, we're gradually moving toward making airplanes fully electric and silent.
25:44Then, we can locate airports closer to city centers.
25:48This will save travel time and reduce the amount of harmful gases emitted into the Earth's atmosphere.