What must a pilot do when reported RVR/visibility falls below the minimum after passing the outer marker during an instrument approach?

When a pilot is on an instrument approach and the reported runway visual range (RVR) or visibility drops below the minimum requirements after passing the outer marker, the appropriate action is to initiate a missed approach. This is critical because continuing the approach under these circumstances would increase the risk of not being able to see the runway or make a safe landing, which could lead to an unsafe situation.

In this scenario, the outer marker serves as a significant reference point in an instrument approach, indicating that the aircraft is nearing the decision altitude/height (DA/H). If visibility conditions worsen after passing this point, it is an essential safety protocol for the pilot to execute a missed approach procedure. This action helps to ensure that the aircraft can safely climb away from the approach path and allow the pilot to reassess the situation, including potentially diverting to an alternate airport where visibility conditions meet the requirements for a safe landing.

The options that involve continuing the approach—either to DA/H or MDA/H—are not suitable in this case, as they could compromise safety if the necessary visual references are not available. Diverting to an alternate aerodrome is also a valid consideration but is not the immediate action required after passing the outer marker in response to deteriorating visibility