What code is displayed when updated data is not being received?

When updated data is not being received, the code displayed is "OLD." This indicates that the information being presented is no longer current and has not been refreshed with new data. It serves as a warning to the observer that they should be cautious when relying on the information, as it may not reflect the latest situation.

In operational contexts, understanding the distinction between old data and updated data is critical for making informed decisions, especially in rapidly changing environments such as air traffic control. The implication of "OLD" suggests that controllers should seek confirmation through alternative means to ensure the accuracy of the information they are using.

"NA" (Not Applicable) typically indicates that a certain function or data is irrelevant in the current context, while "NEW" would suggest up-to-date information is available. "WAIT" often serves as an instruction to hold off on a decision or action until further updates are obtained. Since none of these pertain to the situation of outdated information, they do not apply in this context.