In which situation should a flight crew member not commence a flight?

A flight crew member should not commence a flight if they are aware of a physical disability affecting their license because it directly impacts their ability to operate an aircraft safely. The medical certification process is designed to ensure that all pilots meet certain health standards necessary for flight safety. If a crew member is aware of a condition that could impair their physical abilities or cognitive functions, they have a responsibility to ensure that they do not compromise the safety of themselves, their passengers, or the aircraft. This reflects adherence to the safety regulations set forth in aviation standards.

The other options present situations where flight crew members are either fit to fly or have completed necessary training, which does not inherently present safety risks. Thus, those situations do not warrant the same level of concern regarding flight commencement as the awareness of a physical disability does.