Human factors. At the end of the day the most important component in the plane is the pilot. Without a trained pilot making good decisions the flight runs a high risk of ending badly. However even highly trained pilots can make bad decisions and can be negatively influenced. This lesson was all about the human component in the flight.
Taught by my actual flight instructor, we went into the affects of alcohol on the body, illness, altitude and stress. All factors in accidents. Tiredness is a killer as is going too high without oxygen. There are regulations and guidelines to cover many of these.
Scuba diving is an issue. If you have to make depressurization stops on the way up, you cannot fly for some time afterwards. Dentistry is another issue some don’t think about. Extensive dental work can cause problems if you fly too soon afterwards. Similarly you cannot be in charge of an aircraft after giving blood.