What action should the pilots of a glider and an airplane take if on a head-on collision course?

In the scenario where a glider and an airplane are on a head-on collision course, the correct action is for both pilots to give way to the right. This is in accordance with the regulations governing right-of-way in aviation, which dictate that when two aircraft approach each other head-on, each pilot is to alter their course to the right to avoid a collision.

This rule is crucial for maintaining safety in the air as it provides a standardized method for pilots to react in such a situation. By both aircraft turning to the right, the risk of collision is minimized, as both will effectively create more distance between each other as they pass.

Maintaining their course or giving way to the left would not be appropriate actions since they could still result in a collision. The option of one pilot ascending while the other descends is not typically recommended in a head-on situation, as both aircraft changing their vertical position could still lead to a dangerous encounter if not coordinated properly.