How long must an ACM be downed after undergoing general medical procedures?

The correct duration for an Aviation Crew Member (ACM) to be downed after undergoing general medical procedures is 48 hours. This period is established to ensure that the individual has had sufficient time to recover from the effects of the medical procedure, which may include anesthesia, medications, or other factors that could impact their ability to perform safety-sensitive duties effectively.

Following this 48-hour period allows for a thorough assessment of the ACM's physical and mental state, confirming that they are fit to resume their responsibilities without compromising safety. This precaution is critical in maintaining operational safety standards and effectively mitigating any risk associated with impaired performance due to medical issues.

The other options, while they represent potential recovery times, do not align with the established guidelines for ACMs regarding their reinstatement after medical procedures, which have specifically identified the need for a minimum of 48 hours as an appropriate timeframe for recovery and evaluation.