An IT outage managed to cause a significant decline in air traffic across the United States on Friday. FlightRadar took X to share a 12-hour timelapse video. The footage depicted the dramatic reduction in flight activity following the outage. In the timelapse, American airspace was represented by yellow planes, and hundreds of flights could be seen grinding to a halt.

The chaos erupted early on Friday morning. It stemmed from a faulty anti-viral update from cybersecurity firm CrowdStrike. The update affected Microsoft systems globally. It resulted in a massive disruption, grounding American Airlines, Delta, and United flights. The Federal Aviation Administration confirmed that all flights from these major airlines were grounded in the morning. This, in turn, had a major impact on the day’s air traffic.

Watch the video below:

FlightAware reported that over 4,700 flights experienced delays. Furthermore, 1,800 were canceled in the US by 11 am ET. As the day went on, the skies cleared considerably, proving the extensive impact of the outage on air travel. Passengers across major airports were seen sleeping on jet bridges and in terminals, waiting for rescheduled flights. This includes those in in Los Angeles and New York.

To add salt to the injury, the outage occurred on what was projected to be the busiest travel day in five years. This was due to the start of summer school holidays. It also affected international airports. Airports from London Gatwick to Mumbai reported delays and cancellations, with manual check-in processes being implemented in some locations. In the UK, over 100 flights were grounded. Several airlines, including Ryanair and Wizz Air, issued warnings to passengers about potential disruptions

The CrowdStrike update, installed overnight, led to the infamous “Blue Screen of Death” on many computers. As a result, systems were left inoperable. Microsoft’s Office 365 apps and services were also affected, making the issue worse. Efforts were made to rectify the problem, but despite this, the outage caused widespread havoc. Thousands of passengers were left stranded, and global travel was disrupted.

While airlines worked to resume operations as normal, analysts speculated that the outage might have long-term effects on travel schedules. Cirium estimated that the weekend of July 19-21 would be the busiest of the year for flights.