What conditions must be met to erase data from the cockpit voice recorder?

The correct answer involves the necessary conditions that must be met for a cockpit voice recorder (CVR) to be safely erased. In aviation, the CVR records audio from the cockpit to capture critical communication and environmental sounds during flight. Erasing the data typically occurs under strict conditions to ensure that important information is not unintentionally lost.

Setting the parking brake and powering the hydraulic system indicates that the aircraft is in a stable condition, typically during ground operations. The parking brake ensures that the aircraft is stationary, making it safe to perform maintenance procedures such as data erasure. If the hydraulic systems are powered, it further ensures that all necessary aircraft systems are operational and that the aircraft is in a controlled environment.

While the other options list various operational states of the aircraft, they do not establish the same level of safety and procedural adherence for the erasure of CVR data. For instance, deploying the landing gear or having the engines off does not necessarily guarantee that the aircraft remains securely grounded or that proper protocols are followed. Similarly, having the battery disconnected or APU off may not reflect the operational readiness required, making it unsafe to perform such actions. Thus, having the parking brake set and the hydraulic system powered provides the best framework for safely erasing data from