When should you assume lost communications when being radar vectored prior to final on a PAR or ASR?

When flying in a radar environment, particularly during a Precision Approach Radar (PAR) or an Airport Surveillance Radar (ASR) procedure, it's essential to know how long to wait before assuming lost communications. Assuming lost communications helps pilots maintain situational awareness and ensures safety when operating under radar control.

The standard guideline is that if you are radar vectored and do not receive any further instructions for 1 minute, you should assume that you have lost communication. This timeframe allows for potential delays in transmissions that could occur due to various reasons such as radio interference or communication congestion. If 1 minute has passed without any contact, the proper protocol is to follow lost communication procedures, which would typically involve continuing on the last received heading or altitude, depending on the circumstances.

The other durations provided in the choices are either too short or not aligned with standard practices for lost communications in this context. For instance, 30 seconds may not allow enough time for communication lags, and 2 minutes might be unnecessarily long, delaying safety measures. 5 seconds is also impractical, as it doesn't consider the potential for brief communication interruptions. Thus, waiting 1 minute before assuming lost communications is the appropriate and accepted procedure.