What aspect of cockpit voice recorders allows erasure of older information?

The correct answer relates to the age of the recording. Cockpit voice recorders (CVRs) have a limited recording duration, typically around two hours for most modern units. These devices operate on a loop recording system where once the capacity is filled, the oldest recordings are automatically overwritten by new audio data. This means that as new recordings occur, older recordings are erased based on their age, maintaining only the most recent data within the storage limit.

Understanding this mechanism emphasizes the importance of timely retrieval of recordings after an incident, as critical information could be lost if not accessed before the loop cycles back to earlier recordings. The other options—type of aircraft, weight, and altitude—do not influence the recording process or the erasure of data in CVRs, making them irrelevant in this context.