What should you do if the EMRG blinks in the data block?

When the EMRG indicator blinks in the data block, it signifies an alert regarding the aircraft's status, typically indicating an emergency situation. The appropriate action in this scenario is to change the code afterwards to signal ATC control. By doing this, you acknowledge the emergency status of the flight and proactively communicate with the Air Traffic Control (ATC) system, ensuring that the aircraft receives the necessary attention and resources to address the situation appropriately.

Changing the transponder code communicates the urgency of the situation to other controllers and facilities, allowing them to prioritize the aircraft and coordinate an effective response, which can include arranging for a safe landing or providing necessary support during the emergency.

The other responses would not adequately address the emergency situation presented by the blinking EMRG indicator. Ignoring the signal could lead to dangerous consequences, as it fails to acknowledge the aircraft's emergency status. Requesting an aircraft to land immediately or contacting emergency services are actions that, while necessary in some cases, do not include the crucial first step of changing the code. Therefore, changing the transponder code is a vital first action that enables effective coordination and response to the emergency situation indicated by the EMRG signal.