The US Federal Aviation Administration (FAA) has lifted a nationwide ban on departures from the country's airports. The restriction was in place for around four hours and caused large-scale disruption to air travel, CNN reports.
During this time, more than 6 thousand flights to and from the US were cancelled. At least 1.5 million passengers were affected by the incident. This estimate includes only those whose flights were cancelled, not delayed.
The cause of the incident remains unknown. According to preliminary information, network routers stopped working, leading to a large-scale telecommunications failure and a halt to departures across the country.
US Secretary of Homeland Security Markwayne Mullin said the authorities see no signs of a "malicious attack". He also stressed that the failure was not related to the global Microsoft outage that occurred earlier on 13 November.
