What routing should an IFR aircraft follow if it loses communications?

When an IFR aircraft loses communication during flight, it must follow specific protocols to ensure safety and maintain order in the airspace. The most appropriate course of action is to adhere to the last ATC clearance route or the filed flight plan route. This guideline is grounded in the principles of maintaining situational awareness and minimizing risk to both the aircraft in question and others operating in the vicinity.

Following the last clearance route allows pilots to remain predictable in their flight path, which is crucial for air traffic control to manage the overall traffic and for other aircraft to maintain safe separation. By continuing on the same route, the pilot helps ensure that they remain within established airspace and adhere to the planned altitude, which is essential for avoiding conflicts with other traffic.

In contrast, routing to the nearest airport's traffic pattern or relying on the route in the IFPO (Instrument Flight Procedures) might not align with the established flight plan or lead to conflicts in busy airspace, reducing safety. Furthermore, referencing the file date of the last flight plan would not provide a clear direction for navigation, as it does not specify the necessary routing for the aircraft to follow in the event of communication loss.