From the top menu, select "Aerotow Everywhere" -> "Call for Piper J3 Cub aircraft", "Robin DR400", "Cessna 182" or "Douglas C-47". (Yes, you can choose from many aircrafts.)
The tow aircraft will appear to your right and align to the centreline of the runway in front of you. At this time you should hook up to the aircraft, most often by `Ctrl-o` key. Check help of your glider. The aircraft will begin to accelerate and take off.
The tow plane always takes off in front of your runway and flies along the runway for 5 km, then turns back and flies downwind for 6 km, then turns back again and flies another 6 km. During this flight it is constantly gaining altitude. Then, after having flown the entire given route, it lands at the airport from which it took off or when start in the bush turns in an unknown direction and flies at a constant altitude. If the aircraft lands at the airport, the scenario starts again, i.e. the aircraft respawn to take-off again.
1. When I select "Aerotow Everywhere" -> "Call for Piper J3 Cub aircraft", "Robin DR400" or "Cessna 182" from menu, I see "Let's fly!" message but nothing happened. The tow plane does not appear.
Probably you didn't include the `--data` command line option with the path where FlightGear should look for additional flight plan files for AI. Unfortunately, the simulator does not inform us that there was a problem with finding the flight plan file, so everything looks like it should work but does not.
For fix it, in the file explorer of your operating system, find the directory `$FG_HOME/Export/Addons/org.flightgear.addons.Aerotow`. This path must be added by the `--data` command line option, so it will be treated as an additional FGData directory where FlightGear will find the flight plan. In Launcher go to "Settings" tab and in "Additionnal Setting" type (on the Linux system):