Long-range FPV is one of the hardest aspects of the modern R/C hobby. Not only will you be sending your foam airplane of drone miles and miles above the line of sight range, if anything goes wrong, but you will probably never recover your UAV. Dead servo, burned motor, broken linkage, or just depleted battery equals crash. Finding your model miles away is extremely hard even if you know the GPS coordinates and last known position. Before making a first long-range flight, do everything you can to ensure your airplane or a drone will come back safely.
Here are tips about how to do that. But bear in mind, that I will skip the most obvious tips like: