An aircraft on an IFR flight plan is considered overdue after how much time has passed without communication or radar contact?

An aircraft on an IFR flight plan is considered overdue after 30 minutes without communication or radar contact. This timeframe is significant because the nature of IFR operations involves a higher level of oversight and communication with air traffic control. When a flight deviates from its expected communication patterns or is lost from radar, a window of 30 minutes allows air traffic control to initiate procedures to trace the flight or take further action, such as alerting search and rescue operations if necessary.

The 30-minute mark strikes a balance between giving enough time for typical delays or non-communication while ensuring that safety and quick response measures can be enacted without unnecessary delay. This protocol aligns with the urgency needed for IFR operations, where pilot and controller interactions are crucial for maintaining safety in controlled airspace.