Final answer:
Individuals who have donated blood should wait 56 days before controlling air traffic as an ATC personnel.
Step-by-step explanation:
According to the American Red Cross, individuals who have donated blood should wait 56 days before controlling air traffic as an ATC personnel. This waiting period is necessary to ensure the donor has fully recovered from the blood donation and does not experience any complications while performing their duties. It helps to maintain the safety and well-being of both the donor and the individuals they are responsible for directing in the air traffic control.