When should you assume lost communications when being radar vectored on final for an ASR or no-gyro?

The correct response of 15 seconds is based on standard aviation procedures related to lost communications during approaches, particularly when being radar vectored for an Approach Surveillance Radar (ASR) or no-gyro approach. If an aircraft being radar vectored on final does not respond to radio communication for 15 seconds, it is generally acceptable for pilots and air traffic controllers to assume lost communications.

This 15-second timeframe provides enough opportunity for a pilot to respond, considering potential distractions or temporary communication issues. It also aligns with air traffic control protocols that prioritize safety and effective handling of aircraft approaching for landing.

As pilots are often in a critical phase of flight during final approaches, this assumption aids in swift decision-making, allowing controllers to take necessary actions to ensure safety and maintain orderly operations. Thus, the 15-second rule serves as a guideline for both pilots and air traffic controllers to manage communication effectively during these critical moments.