Outlandings are a regular occurrence when gliding cross-country. During competitions with tens of participants, it is not uncommon for a few gliders to land out each day. For this reason, in the UK at least, glider pilots are taught how to land out, and think about this eventuality on every flight. Many will have experienced a landout with an instructor before going solo, and practice approaches to fields are a requirement of gaining the cross-country endorsement (part of the UK syllabus).
In practice, there isn't a lot to do after your beautifully-executed landing. In common law countries (including the US and the UK) on private land you are trespassing, and the landowner can ask you to leave. Of course this is already your intention, but it's complicated by the expensive machine you have just deposited there. Any damage you cause (or caused, on your way in) is your liability. Your aircraft is still yours, and the landowner cannot prevent you from removing it. If he tries, he is responsible for keeping it safe and will be liable for any damage. He can charge a reasonable fee for his time and the unauthorised use of his land, but often will not. Some landowners object to professional balloon companies charging large sums for taking parties of champagne drinkers into their fields and want a cut of the profits. In this case, remind him that you are a private individual and that you landed there without intending to in an emergency.
So your plan should basically be:
- Make the aircraft safe.
- Inform whoever you were most recently in contact with that you have landed safely (ATC, or your fellow travellers on common frequencies).
- Find the landowner, explain that you didn't mean to land there, that it was an emergency and that you intend to retrieve your property as soon as possible. Obtain permission for vehicles to enter his land.
- Contact your friends to bring the trailer, derig the aircraft and drive home.
- Buy dinner for your friends.
If you have approached over built-up areas or roads, someone will probably have seen you and is likely to call the emergency services on your behalf. In the UK, NATS (the National Air Traffic Service) coordinates with the police in cases of aircraft outlandings. You should call their distress and diversion (D&D) cell to inform them of the situation, even if there is no damage or injury.
If the landowner tries to impound your aircraft or becomes aggressive, call the police. There have been cases where landowners have caused damage to aircraft and recourse was only possible because of police attendance.
If you have caused any damage, try to come to an agreement on the cost. Often, young crops are not damaged by landing aircraft, and if you have landed in a long crop you are probably not capable of discussing compensation. Ploughed fields and grass fields are more likely to have damaged your aircraft than the other way round.
Outlandings are not the end of the world. If it worries you, why not hop along to your local gliding club and take a flight. Most instructors will be more than happy to show you round the local fields!