What altitude filter setting must be used on a radar display in order to follow airspace limits?

Using an altitude filter setting of at least 1000' above and below airspace limits is essential for effectively monitoring and managing air traffic within controlled airspace. This filter maintains a safety margin that ensures all aircraft operating at or near the airspace boundaries are visible, providing a buffer to account for any possible altitude deviations.

This parameter allows air traffic controllers and other users of radar displays to have a clear understanding of the airspace limits and ensures that no aircraft inadvertently breaches these restrictions. It helps in maintaining safe distances between aircraft and provides an additional layer of situational awareness, crucial for both safety and efficient traffic management.

Regarding the other options, settings that are too shallow, such as 500' above and below, might not provide an adequate safety buffer. Conversely, while 1500' above and below could enhance safety further, it may unnecessarily obscure some aircraft that are operating close to these limits and complicate the display without adding significant value in terms of safety. Thus, the choice of 1000' above and below strikes a balance between safety and operational efficiency.