By Daniel Emery
Technology reporter, BBC News
Avsim was one of the largest sites serving the flight sim community
Flight simulator site Avsim has been "destroyed" by malicious hackers.
The site, which launched in 1996, covered all aspects of flight simulation, although its main focus was on Microsoft's Flight Simulator.
The attack took down the site's two servers and the owners had not established an external backup system.
The site's founder, Tom Allensworth, said that the site would be down for the foreseeable future and was unsure if it would ever go back up.
"The method of the hack makes recovery difficult, if not impossible, to recover from," Mr Allensworth said in a statement.
"AVSIM is totally offline at this time and we expect to be so for some time to come. We are not able to predict when we will be back online, if we can come back at all. "
The attack has shocked the flight sim community, with hundreds of blogs, posts and tweets. One user on the simflight.com website said that "there's a special place in hell for hackers who pull stunts like this".
Speaking to the BBC, Derek Davis, editor of PC Pilot magazine, said: "It looks like 13 years of hard work on Tom's part could have been wiped out.
"Avsim is an important site, because it services the whole community as a source of community developed terrains, skins, and mods - its contribution has been immeasurable," he said.
Mr Allensworth has set up a temporary forum for Avsim users while the future of the site is decided.
On it, he explained the site's backing-up process, although he did not explain why the firm had no external media storage.
"Some have asked whether or not we had back-ups. Yes, we dutifully backed up our servers every day. Unfortunately, we backed up the servers between our two servers.
"The hacker took out both servers, destroying our ability to use one or the other back-up to remedy the situation."
Mr Davis said he thought the site still had a future: "I'm sure Avsim will rise like a phoenix from the ashes and will be bigger and better than before."