"...FlightGear is 100% free, as in speech and beer. It can be
downloaded from their website at http://www.flightgear.org. It's
open source under the GPL and works on Linux, Windows, Irix, and
"We wanted something that was cross-platform and fully
extensible," John said. Alex Perry, another developer, added, "It
needed to be completely modular and open source was really the only
way to go."
"FlightGear boasts accurate terrain and land cover, runway
markings, roads, urban lighting, ILS approaches, visibility,
clouds, wind, sun, moon, stars, and VOR ADF DME aids for cross
country. How can they promise all this? Easy. Some of the
developers are pilots, so they're building from personal
experience. Alex modeled one of the scenarios after the airport he
flies out of, and uses it to train other pilots using familiar
landmarks. John confided in me that one of the team's ultimate
goals is for the program to become an FAA-certified flight trainer.
One of the developers on the team has even flown a Boeing 747 and
is working on simulating it with FlightGear (although they don't
expect that module to be finished for several years)."