Why don't Chinese planes flying to the US cross the Pacific Ocean?

The first human flight across the Pacific Ocean was in 1928, flown by Australian pilots Charles Kingsford Smith and Ulrich. However, due to the conditions at the time, the flight was not a continuous flight, but took off from San Francisco, stopped in Hawaii and Fiji, and then arrived in Australia to complete the entire journey.

On July 20, 1997, a Boeing 777-200ER aircraft of China Southern Airlines departed from Guangzhou and arrived at Los Angeles, the United States, on the other side of the ocean in 13 hours and 13 minutes, completing the first non-stop commercial flight across the Pacific Ocean in human history. This leap created a glorious legend written by Chinese pilots and was permanently recorded in the history of world civil aviation.

The shortest route from China to the United States is across the Pacific Ocean. Why is this flight hailed as a "legend"? Hasn't the route from China to the United States been across the Pacific Ocean for many years?

The answer is this. Most Chinese aircraft will first fly towards Japan, then stick close to the coastlines of Russia, Alaska and Canada, cross the North Pacific, and enter the United States in an arc.

So why fly like this?

Let's first discuss the route selection criteria. First of all, the route selection needs to comply with international aviation control. The so-called international aviation control is a general term for the unified supervision, management and control of all flight activities in a country's airspace or a certain airspace in peacetime or wartime. In layman's terms, all airspace of a country cannot allow civil aircraft to fly at will.

Secondly, the choice of route should be economical. In order to minimize costs and gain profits, airlines generally choose routes with the shortest distance between the departure point and the destination, which can effectively reduce travel time and reduce aviation fuel consumption. However, there are exceptions, which we will mention later.

Third, the setting of routes needs to consider safety. The climate of each region of the earth is different, and the weather is changeable. For example, the Bermuda Triangle in North America has many tropical hurricanes in summer and autumn. The howling winds often form water walls more than 10 meters high, and seaspouts often appear, which can suck seawater to a height of thousands of meters. For safety, airlines generally choose airspace with relatively stable weather changes and good climatic conditions.

Under the above three principles, will airlines definitely choose to cross the Pacific Ocean? No! Because the earth is round, not flat, so the shortest distance on the map is not the shortest distance of the actual flight route. In actual flight, the shortest path is the "great circle route".

We know that two points determine a straight line, and three points determine a plane. If we regard the earth as a sphere, then any two points on the ground plus the center of the earth form a plane, and the circumference obtained by the intersection of the plane and the surface of the earth is the great circle. The great circle inferior arc between two points is the shortest distance between the two points on the surface of the earth. Using the relevant formulas of spherical triangles, the great circle routes of various routes can be quickly calculated. In low-latitude areas, or when the route is short, the distance between two points and a line is not much different from the range of the great circle route, but in high-latitude areas, or when the route is long, the great circle route can save hundreds or even thousands of nautical miles.

If we fly from Shanghai to New York, because Shanghai is nearly 180° away from New York in longitude, the great circle route from Shanghai to New York will cross the Arctic Circle. However, the actual flight route from Shanghai to Los Angeles is slightly southerly than this great circle route. After the plane flies over Japan, it crosses the North Pacific. Although this flight route is longer than the great circle route, the flight time will be shorter. This is because in the mid-latitudes of the Northern Hemisphere, there is a high-altitude jet stream belt at the top of the troposphere and the bottom of the stratosphere, and westerly winds blow in this jet stream belt all year round. With the help of westerly winds, aircraft can obtain a ground speed of more than 1000km/h. So although the flight distance is a bit longer, the time is shorter, fuel is more economical, and it is more economical for airlines. Because of the headwind, flights from the United States back to China do not fly along this route. They generally choose to take the great circle route, that is, from near the Arctic Circle.

In fact, flying north also has safety concerns for airlines and passengers. Because flying along the coastline, there are many airports in Alaska, the United States and the Chukotka Peninsula, Russia that can be used for emergency landings. If the plane flies over the Pacific Ocean, there are very few island countries in the Pacific Ocean and the number of airports is also very scarce. Once an accident occurs, it is difficult to get good rescue.