Under what circumstances are aircrew permitted to donate blood?

Aircrew members are allowed to donate blood under specific regulations that prioritize their health and the safety of flight operations. When a crew member donates blood, there are several considerations to ensure that they can perform their duties effectively and safely after the donation.

The correct circumstances outlined in the choice highlight the necessity of obtaining the commanding officer's approval before making the donation. This approval process ensures that the command is aware of the operational capability of its personnel and can adequately make arrangements if the donation could affect duty performance.

Additionally, imposing a Temporary Mobilization Unfitness for Flying (TMUFF) period of 72 hours serves to safeguard aircrew members by providing sufficient recovery time after the donation. This timeframe is essential as it allows for the restoration of blood volume and hemoglobin levels, which are critical for maintaining physical performance and cognitive function required when flying.

In contrast, other options either do not include the necessary protocols around CO approval or fail to address the appropriate TMUFF timeframe required post-donation, thereby compromising aircrew safety and operational effectiveness.