Before the pandemic, there were about 12,000 planes in the sky at the same time, with a record of 19,000.
Every day millions of passengers took off from airports and thousands of flights were made, before Covid-19. With the help of online flight tracking systems around the globe, anyone can easily view the number of planes on a map at a time. You can track the number of aircraft thanks to the “Automatic Monitoring” system (ADS-B) . It is installed on most aircraft, works under the global positioning system GPS.
On average, there are about 11,000-12,000 planes in the sky at the same time. They fly at different altitudes with different speeds, serving different purposes such as passenger, cargo, postal… All coordinated by air traffic controllers. They “separated” the planes, preventing them from coming closer than 5 km. The aircraft can fly at an altitude of 300 m. Therefore, even though the flight path of the aircraft appears chaotic on the online radar system, the actual airspace is very tightly controlled so that a large number of aircraft can be safely in the sky at the same time.
The number of planes varies at different times of the year , peaking in July and August, the summer tourist season. And with more flights taking off in the summer than in the winter, the number of planes in the sky at the same time in the summer can be as high as 16,000. 
19,285 aircraft were recorded at the same time. (Photo: Flight Radar 24).
The record for the number of aircraft in the sky at once was recorded on June 29, 2018 with more than 19,000 according to Flight Radar 24, a website that tracks aircraft in real time. It was also the first time the system tracked 202,157 flights in a single day.
The number of aircraft is most concentrated in the US, Europe, the Middle East and Southeast Asia. Areas without planes are western China, the Asian part of Russia, northern Scandinavia, Central Africa and western Australia.
The screen monitors the journey of aircraft in the US for 24 hours on April 1, 2016. (Video: FlightRadar24).
Despite the increasing number of flights, the Aviation Safety Network (ASN) says only 85 planes have gone missing since 1948. The last passenger flight to mysteriously disappear was Malaysia Airlines MH370 in 2014. .