Under CDR Part 91, what must a pilot ensure when taking medication before acting as a crew member?

The correct answer emphasizes the pilot's responsibility to ensure that any medication taken does not negatively impact their operating capabilities in a manner that could jeopardize safety. Under 14 CFR Part 91, pilots have a duty to assess whether their physical and mental abilities are sufficient to safely perform their duties as crew members. This involves considering any medications they may be taking.

Safety is paramount in aviation, and a pilot must carefully evaluate the effects of any medication on their faculties. This choice reflects the regulation's intention to prioritize situational awareness and operational safety, as the pilot must not merely rely on lists or time frames but take a proactive approach in understanding how any substance may influence their performance.

While the other options may suggest permissible actions or guidelines regarding medication use, they do not align with the core requirement of ensuring that medication does not impair a pilot's capabilities, which is crucial in maintaining safety during flight operations.