If you are in a helicopter or float plane, your aircraft probably does not have a parking brake available. This can make it difficult to end your FSEconomy flight.
You can edit your aircraft's configuration file (aircraft.cfg) to add a parking brake, even during "mid-flight". (many people land and discover that they have no parking brake, and need to make this adjustment before they can get credit for their flight). Find the following two lines in the [brakes] section and adjust them to read as follows. Once you make this adjustment, you can simply reload your aircraft (CTRL+SHFT+R by default, or go into your aircraft menu and select the same aircraft you are in). If your model does not have a [brakes] section, then copy and paste the following three lines into the aircraft.cfg
[brakes]
parking_brake = 1
toe_brakes_scale = 0.75