On January 11, 2019, the SpaceX Falcon 9 launch vehicle launched into orbit the final batch of 10 vehicles for the "constellation" of Iridium NEXT satellites. In early February, the completion of work on the formation of a new constellation was announced, which now includes 75 objects - 66 active satellites and 9 spare ones. It expands the worldwide use of ADS-B aircraft tracking technology.
The transition to ADS-B technology began in 2010 and is still far from complete on a global scale, but this is the future. Many airports, especially in third world countries, still use old radars to determine the location of airborne objects. With an ADS-B transmitter, each aircraft itself continuously notifies the outside world about its current coordinates. You just need to receive this signal - previously, towers on land were used for this, but with the advent of Iridium NEXT, the coverage area has spread to the oceans.
Iridium NEXT satellites are located at an altitude of 1360 km above the planet and each of them serves the space within a radius of 3, 5 thousand km. Coverage areas overlap each other, so to filter duplicate signals from aircraft, the data will be processed in a data center in Virginia, and from there it will be sent to a specific flight control organization in different parts of the world. At the same time, the developers of Iridium NEXT guarantee that the whole process will take no more than two seconds - during this time the board will fly a maximum of several hundred meters.
Before the advent of ADS-B, air traffic controllers often had to determine the position of aircraft at a large distance using procedural methods, they did not know, but only guessed where the aircraft was flying. Because of this, it was necessary to separate the planes over a long distance, for the sake of reinsurance, and in the event of a crash, the search area was enormous. Now, both the accuracy and the amount of information about aircraft in the sky will increase, which will increase the efficiency of their control. To do this, in Western countries, airports are already massively sending employees for retraining.