When must a student pilot complete a written examination?

A student pilot must complete a written examination before solo flight because it ensures that they have a solid understanding of the necessary aeronautical knowledge required to operate an aircraft safely without an instructor on board. This examination typically covers topics such as navigation, regulations, weather, and aircraft operations, which are essential for making informed decisions while flying solo. Passing this written test demonstrates that the student pilot has the foundational knowledge to handle the responsibilities that come with flying alone, which is critical for safety.

The other options do not align with the requirements set by the FAA for student pilots. For instance, a written examination is not mandated before applying for a student pilot certificate, joining a flight school, or undergoing a medical examination. Therefore, the timing of the written test directly relates to the readiness of the student pilot to fly independently.