As many people will be aware, there is a new flight simulator product that is being widely and actively marketed at the moment - Flight Pro Sim. As it is almost entirely based on FlightGear, there is some confusion between the two. To help provide some clarity, and answer some common questions, we (the core FlightGear development team) felt it was appropriate to make a statement, and provide a FAQ.

FlightGear is an open-source flight simulator that was started in 1996. It is released under the GNU General Public License v2, and as such, it is free to use, modify and distribute with few restrictions. It has been developed with the collaboration of a large number of individuals over the last 12 years. FlightGear can be downloaded at no cost from http://www.flightgear.org.

Flight Pro Sim is a commercial product very heavily based on FlightGear. Investigation by a number of the FlightGear developers has found no difference between this and the FlightGear v1.9.1 release other than a change of name. Flight Pro Sim is in no way endorsed or supported by the core FlightGear development team. Given the similarities between Flight Pro Sim and FlightGear, we would recommend that prospective buyers download FlightGear for free and satisfy themselves that Flight Pro Sim provides worthwhile value for money before purchasing it.

I bought FlightProSim, what to do?

If you have bought FlightProSim, try to get your money back as soon as possible. You can have (almost) the same software for free nevertheless! They guarentee a 60 day money back trial period, so this should be no problem if you react quickly.

The FlightGear developers are interested in the package to see whether the package complies with the GNU GPL terms or not. Therefore we would like to receive a package for inspection. If you own a package and were unable to get your money back, please contact the developers through the mailing list.

Legal or illegal?

The GNU GPL license under which FlightGear is released allows reselling under certain terms. Many FlightGear developers have difficulties with the way FlightProSim is acting and doubt if they are acting legally. If you have any (inter)national law knowledge, please contact the developers at the mailing list, they will welcome any legal support.

What are the differences between the two?

As far as we have been able to make out, the only difference between FlightGear v1.9.1 and FlightProSim is a change in name throughout the software, and the fact that you have to pay for it.

Why did you refuse a money offer from FlightProSim?

After a lot of negative criticism from the FlightGear developer, FlightProSim offered to fund a competition in which a developer of a nice new feature is rewarded with a sum of money ($250). The FlightGear developers have more or less un-officially decided to not accept the money offer. A couple of the reasons include:

  • If the guy behind FPS really is interested in improving a flight sim, he would input his addons/improvements back into the FlightGear community so the software can be further developed.
  • Everyone is allowed to sell FlightGear, as long as they comply with the GNU GPL v2 license. FPS did not in the past, and thus we do not trust them any more. Only after lots of requests from our side they changed their website telling the visitors (in a very small message without link) that it is actually an adaption of free software
  • FlightProSim also copied all content from our wiki (and initionally also our main website). That does not give a positive developer impression, more like a "we-want-money-fast-and-without-much-effort" attitude. Apart from the fact that FPS is actually part of a money making company, rather than a software developing one...

Why do FlightGear developers allow this?

The freedom to modify and enhance FlightGear is a core part of the project, and of open-source in general. Restricting the modifications that are allowed and what people can do with the software goes against that ethos.