Under what condition should a safety alert be issued?

A safety alert should be issued when an aircraft is in unsafe proximity to terrain or other aircraft because this situation poses an immediate threat to the safety of the flight. The primary responsibility of air traffic control is to ensure that aircraft operate safely and efficiently within controlled airspace. If an aircraft gets too close to either terrain or another aircraft, it signifies a potential for mid-air collision or controlled flight into terrain (CFIT) incidents, both of which can have catastrophic outcomes.

In contrast, experiencing turbulence does not typically require a safety alert, as turbulence can be anticipated, and pilots are trained to handle it. Approaching a sector boundary is a normal part of flight operations and does not inherently constitute a safety threat that would require alerting concerned parties. Additionally, flight delays are often a routine operational issue and do not relate directly to safety concerns that would warrant a safety alert. Thus, the issue of unsafe proximity stands out as an urgent matter necessitating the communication of a safety alert.