字幕表 動画を再生する 英語字幕をプリント Look! Up at the sky. It’s a bird. It’s a plane! Well almost. Right now, there are about 10,000 planes carrying almost 1½ million people from one point to another. But once you're on the plane and look out the window, it seems as if your aircraft is the only one dashing across the sky. The sky may seem deserted, but it's just an illusion. Planes can't just fly wherever they want - they need to follow special routes. These routes are more or less the same for all aircraft, and during your flight, several other planes are likely soaring nearby. Sooo, where is everybody? Oh, they’re there, alright…just not, right there! For one thing, your field of vision is limited by the small window that only allows you to look out one side of the plane. Even if another airliner was flying along the same path, you wouldn't notice it from your seat. Pilots, on the other hand, have a massive windshield and can see other planes flying in front of them from the cockpit. But if another jet is traveling behind, below, or above, even the pilots won't be able to spot it with their own eyes! The number of planes in the air is impressive, but the sky is big. That's why aircraft don't need to fly side by side - or even close enough for you to see them from your window. White against the clouds, airplanes are also difficult to spot. They look like tiny dots, and your eyes must be expertly trained to notice a dot that small. Your neighbor might have eyes trained so well, but we’ll meet those special passengers a bit later! For now, most travelers don't want to waste their time staring at a seemingly empty sky. Or maybe they do? How do you usually pass the time on a long flight? Let me know down in the comments! Bad weather and clouds are another issue here. At night, though, it's easier to notice other aircraft thanks to the flashy lights they’re decorated with. So if you’re looking to spot a fellow jet up there, your chances are better after the sun goes down! What about when two airplanes are approaching and passing each other? Well, both are moving at a breakneck speed of around 500 mph. So you’d need to look out the window at a very precise moment to notice the other aircraft. Blink, and you’ll miss it! But the main reason you don't see many airliners while flying is also why planes don't meet and collide with each other in the sky. And it’s aircraft separation. That's a set of rules that help keep airplanes away from each other. No plane nearby - no risk of a collision. By the way, separation can also refer to other obstacles and even a country’s airspace. Pilots know which airspace blocks they can fly through. Before entering a new block, they must get permission from a controller. When a smaller plane is traveling behind another, much larger one, it's likely to experience wake turbulence. This kind of turbulence is mostly created by the bigger aircraft's wings. Thanks to separation, the risk of collision becomes minimal, and smaller planes aren't affected by wake turbulence. There’s a popular misconception that only air traffic controllers are responsible for keeping airplanes away from one another. The FAA states that every pilot is also in charge of avoiding wake turbulence and keeping the necessary distance from another jet. An airplane's size means a lot as well. Big commercial airliners are mostly operated with the help of special equipment. It allows them to fly in different weather conditions, at night, and when visibility is low, like in the clouds. A lot of small private aircraft don't have these special instruments, and pilots operate their planes mostly when the weather is clear. Besides listening to air traffic controllers, those pilots have to rely on their sight. Meaning, they can only see where their airplane is going when visibility is good. Aircraft separation can be vertical (when one plane is flying over the other) and horizontal (when two are flying side by side). If two aircraft are flying below the cruising altitude of 29,000 ft, one of them shouldn't get vertically closer than 1,000 ft to the other. If the distance from the surface is more than that, the planes have to keep a vertical distance of 2,000 ft. Pilots can only break this rule if there’s a necessary horizontal separation between them. The rule is that there must be about 6 horizontal miles between two airliners flying at the same altitude. In regions with poor radar coverage, the distance between planes must be more than 11 miles. If it's happening in an airport’s airspace, separation can be smaller - 3.5 miles. At the airport, for example, during taxiing, landing, or takeoff, airplanes get pretty close to one another - the main rule is to keep a safe distance between jets. Sounds like a lot to remember, I know. But don’t worry – we have computers to help us with that! Most modern planes with more than 10 seats are equipped with a TCAS, which stands for Traffic Collisions Avoidance System. Its main task is to warn a pilot if another aircraft is coming close at the same altitude. The equipment calculates the time it’ll take the other plane to get so close that a collision may happen. When this time starts to run out, the system starts making shrill warning sounds. The TCAS shows a map with aircraft traveling nearby. (Some systems have a separate monitor for that, some display the map on other screens like the weather radars.) On the map, pilots can see their own planes at the bottom of the screen. Airliners that are far away and harmless look like empty diamonds. When one of the planes approaches closer than 6 miles horizontally or 1,200 ft vertically, its diamond gets filled. Any closer than that, and the diamond turns into an amber dot, and an automated voice starts saying urgently, "Traffic, traffic." A pilot must react immediately so that the yellow dot doesn’t become red. If an airplane has more than 30 seats, it's supposed to have an advanced TCAS. Two systems of this kind installed on different planes communicate with each other and coordinate the jets so that they can avoid a collision. In this case, one pilot will hear "climb, climb" coming from their system, while the other TCAS will tell its pilot "descend, descend." Before the early 90s, very few aircraft had any equipment that could help prevent collisions. Pilots had to rely on their own eyes and air traffic controllers. Early versions of the TCAS were pricey, and since they had to be installed on every plane, imagine the money airlines had to pay to renovate all their jets! But the obvious need to prevent mid-air collisions settled the matter once and for all: every airplane needed a TCAS whatever the cost. Get this: most passengers might not notice any other airplanes out the window, but pilots riding as passengers do! Their trained eyes can easily spot nearby jets. But that's not the only thing they pay attention to. If their view isn't clear enough because of the ice that's accumulated on the windowpane, it's a red flag. In cold weather, snow and ice are removed from an airplane before the flight. Then the aircraft gets coated with a special substance that prevents ice build-up when the plane’s in the air. This substance works for some time, but several hours into your flight, you may notice that your window is covered with a light layer of frost again. That’s normal since the temperatures outside your plane are freezing. But if there’s a thick coat of ice covering the windowpanes, it could mean that the engines aren’t generating enough heat. An airplane covered with ice may have serious flying and landing problems: the ice disrupts the smooth airflow and reduces the lift that keeps a plane in the air. So, if you can't see other jets in the sky because of the thick ice on your window, it’s something worth mentioning to the crew! But they probably already know and have started taking the necessary steps to keep you and everybody else onboard safe! By the way, I heard that pilots are trying to get another system in their flight decks call an E-COF. That stands for Empty Coffee Avoidance System. Yep, if their coffee cups get too low, the alert sounds “refill, refill”. Hey, if you learned something new today, then give the video a like and share it with a friend! Even that bad joke. And here are some other videos I think you'll enjoy. Just click to the left or right, and stay on the Bright Side of life!