Speaking of "blocking airplanes", people are actually very familiar, because every time a plane is delayed, the channel is "blocked". The sky is so big, why is the "little" plane still blocked?
The largest traffic jam in history
Most of the time, people will encounter short or long delays when taking a flight. However, on September 11, 2001, people flying to or departing from the United States encountered this "aircraft jam" incident, no matter from The duration and scale are unprecedented.
On September 11, 2001, 4 planes were hijacked by 19 terrorists. Two planes crashed into the Twin Towers of the World Trade Center in New York, USA, causing the twin towers to collapse within two hours, and the third plane crashed into the Pentagon. , The last plane crashed in Pennsylvania after the passengers resisted, and no one survived on the four planes.
After the incident, U.S. President Bush ordered the closure of all air routes to the United States, grounded all civil aviation aircraft in the United States, and even granted the Air Force the right to shoot down civilian aircraft that did not obey orders. For a time, all flights that have not yet departed were suspended indefinitely, and domestic flights that had already departed landed nearby. And those international flights to the United States are like headless flies. Without knowing what happened, the whole world is looking for apron where they can stop temporarily.
Canada’s three major airports have become the home ground for alternate landings. In total, Vancouver Airport, Halifax Airport and Gander Airport have parked more than 100 international flights from all over the world. Passengers on flights stayed there for three days before they were able to line up. Waiting for the flight to the United States, it took another two days for the US airport to evacuate all stranded flights and passengers.
The air traffic control center can meet the needs of any air traffic control environment. The air traffic control center includes towers, control centers, training and simulation facilities, and data collection and content management solutions.
It can be seen from the above that air traffic control is a major cause of "aircraft jams." Air traffic control is not only implemented in emergency and special circumstances. In fact, in order to ensure airspace safety, it is normal for countries in the world to use civil aviation domains under strict military control. Most of the global airspace is under the direct control of the military, and the airspace that can be used by civil aviation is less than 30%. Whenever there is an accident or military exercise, the civil aviation domain is usually controlled or even closed. , The plane will be "late" or even miss. In addition, similar to road traffic, as there are more and more airplanes and more and more congested waterways, the daily control of airplanes has gradually increased. The aircraft route has a fixed range. For example, the Beijing-Guangzhou route is an air passage with a width of 20 kilometers and a height from 0 to 14,000 meters. The aircraft can only fly on this route without any deviation. In addition, a certain amount of space must be reserved during the flight of the aircraft, and the distance between each aircraft at the same altitude must be tens to hundreds of kilometers, and the vertical distance must be hundreds of meters. In this way, looking at a very wide channel, it is divided into limited "lanes", and as the number of aircraft increases, "aircraft jams" will appear from time to time, and aircraft must be traffic police in the air—— Taking off, sailing and landing under the command of the air traffic control, the plane was delayed again for the passengers.
The changeable weather causes a traffic jam
For road traffic, severe weather such as heavy storms, heavy fog, sand and dust is an important cause of traffic jams. For airplanes, not only these severe weather, but even small raindrops and slight changes in wind direction must be paid attention to. However, “blocking” caused by weather changes is even more commonplace.
One of the driving forces for an airplane to take off is the lift caused by the air pressure difference. Therefore, changes in air pressure and wind are very important to the airplane. Whether it is at low altitude or high altitude, aviation staff must pay close attention to changes in wind direction, otherwise they will be accidental. It may cause the consequences of plane destruction and death. Low-altitude wind shear refers to the phenomenon of sudden changes in wind direction and speed that occur in areas below 600 meters in altitude. If a low-altitude wind shear occurs during the initial take-off or landing phase of an aircraft, the sudden change in wind direction or wind speed will cause the aircraft's lift The sudden increase and decrease disrupted the stable flight state of the aircraft. Because this change takes place in a very short time, the pilots are too late to react and are often helpless, and thus are prone to aircraft crashes.
There have been many tragedies caused by low-altitude wind shear in history. In June 1975, a Boeing 727 aircraft encountered low-altitude windshear and crashed during its landing at Kennedy Airport, killing 113 people and injuring 11 others. As a result, low-altitude wind shear began to attract people's attention, and a series of studies have been carried out on this, but with little success.
So far, low-altitude windshear still threatens flight safety and has caused many air crashes: In June 2000, an aircraft of Wuhan Airlines crashed due to low-altitude windshear while landing; in 2009, a U.S. airliner was again affected by low-level windshear. It crashed due to low-altitude windshear; in 2017, an Air New Zealand A320-200 aircraft encountered low-altitude windshear during landing, causing serious damage to the passenger plane and causing serious economic losses...
At present, our main technical means to track low-altitude windshear is the weather radar installed in the foremost radome of the aircraft. It can quickly scan to find changes in low-altitude wind speed and direction and alert the pilot of risks. However, due to the fact that the aircraft is close to the ground and fast, it is still difficult for pilots to react quickly, so the danger of low-altitude windshear is still great. In this regard, the best way to deal with this is to delay the take-off or landing of the aircraft whenever there is a weather near the ground that may cause low-altitude wind shear, such as typhoons, gusts, etc., so that disasters can be avoided as much as possible.
At high altitudes, there are even more meteorological crises that airplanes need to avoid. The strong wind zone in the troposphere or stratosphere is called the jet stream. The jet stream has a maximum wind speed of more than 30 meters per second, which can easily generate strong turbulence, which greatly increases the probability of aircraft turbulence and may even damage the structure of the aircraft. If an aircraft encounters a thunderstorm while sailing, its electric field will seriously interfere with radio communications and even interrupt communication. The aircraft may also be shocked, which will seriously affect flight safety. Thunderstorm clouds also contain a large number of supercooled water droplets. When the plane passes through the clouds, the small water droplets will easily freeze on the surface of the plane. If the ice layer is thick, the plane will lose its balance.
In recent years, more and more accurate weather forecasts can enable us to predict the possible dangers that aircraft may encounter in advance, but there is still no way to completely eliminate these dangers. For the sake of safety, it is natural to delay the time of take-off. If the aircraft encountered a sudden meteorological crisis during the voyage, it would have to circle around the place and wait for the natural disappearance of the dangerous weather or the air traffic control's instructions to adjust the flight route. The above-mentioned various factors will eventually lead to the occurrence of aircraft "jamming" and delays.
The occurrence of "blocking traffic" may bring people many troubles and problems, but the occurrence of this event is not only unpredictable, but also if forced navigation is likely to bring greater troubles and dangers, so the next time I encounter "blocking" Let’s wait patiently for the “machine” event.
