What action should be taken according to lost communication procedures when radar is required for approach?

The appropriate action when radar is required for an approach and there is a loss of communication is to coordinate lost communication instructions. This step is essential because it allows the pilot to follow the established procedures outlined for scenarios where they cannot communicate effectively with air traffic control (ATC).

Coordinating lost communication instructions ensures that the pilot understands what to do in that situation, including potential routes, altitudes, and other operational guidelines that must be followed for safety. This coordination is critical to prevent misunderstandings and miscommunication that could lead to hazardous situations.

In contrast, immediately initiating a missed approach without coordination might disrupt the flow of air traffic and could lead to confusion or safety hazards, as other aircraft may not be aware of the sudden change. Continuing the approach without any changes would not account for the loss of communication and could jeopardize safety, given that the pilot wouldn't have updated guidance from ATC during a critical phase of flight.

Contacting ground control for assistance would not be appropriate during an approach phase when the aircraft is often directed by air traffic control. Ground control typically handles taxiing and parking situations rather than airborne approach operations. Thus, following the lost communication procedures by coordinating lost communication instructions is the correct and safest approach in this scenario.