What condition may lead to an aircraft losing radar contact?

An aircraft may lose radar contact if it proceeds into non-RADAR coverage. This typically occurs when the aircraft flies into an area where radar systems are unable to provide tracking information, such as over oceans or remote terrain where radar infrastructure is sparse or nonexistent. In these regions, the limitations of radar technology mean that air traffic controllers can lose sight of the aircraft, making it impossible to maintain continuous monitoring of its position, altitude, and flight path.

The other options present scenarios that might impact communication with an aircraft but do not directly cause the loss of radar contact in the same definitive manner as entering non-RADAR coverage. For example, while a course alteration could potentially lead to a loss of contact if it results in the aircraft exiting radar coverage, it does not inherently result in losing radar contact if the aircraft remains within radar range. Equipment failure could also cause a loss of contact, but this is typically linked to issues within the aircraft’s own systems rather than the limitations of the radar infrastructure itself. Entering a no-fly zone is more of a regulatory concern that may lead to intervention by air traffic control rather than an immediate loss of radar contact.