Which of the following is true regarding radar coverage for aircraft flying in the 48 contiguous states?

Radar coverage for aircraft in the contiguous United States is not uniform and varies based on several factors, notably altitude and distance from radar facilities. The radar systems used for air traffic control operate within certain ranges and have limits in detecting aircraft based on these parameters.

Aircraft flying at higher altitudes typically experience better radar coverage, as they are more likely to be within the operational range of radar signals. Conversely, if an aircraft is flying at a lower altitude or is far from a radar site, it may encounter gaps in coverage. Additionally, geographical features such as mountains and obstacles can further influence the effectiveness of radar detection.

This understanding highlights why consistent and reliable radar coverage cannot be assumed at all altitudes or locations across the country. Thus, the statement that there is not always radar coverage due to dependence on altitude and distance from radar facilities accurately captures the complexities of radar coverage for aircraft.