Amid the Russia-Ukraine war, users of the global flight tracking service Flightradar24 encountered denials of service due to massive traffic as people wanted to know the status of their flights due to airspace restrictions.
The website displayed a 'cancelled' message, making it impossible to access the service.
Flightradar24 is a global flight tracking service that provides real-time information about thousands of aircraft around the world.
On Thursday, as Russian forces invaded Ukraine, it experienced traffic rates 10 - 20 times higher than normal, reports ZDNet.
"Due to extremely heavy load, some users may experience slowness or temporary connection issues accessing Flightradar24. We are working on increasing available performance now," the organisation was quoted as saying.
"We are still working hard on increasing the capacity, but the very big international interest generate[s] 10-20 times higher traffic than normal, which is hard to handle," it added.
Civilian flights in Ukraine have been restricted and the country's airspace is closed due to military action.
Ukraine cited a high risk to safety and the European Union Aviation Safety Agency (EASA) has now listed Ukraine's airspace as an active conflict zone in a new Conflict Zones Information Bulletin (CZIB).