What is the recommended action instead of erasing or overwriting information on a flight progress strip?

Using an "X" to delete unwanted information on a flight progress strip is the recommended action because it maintains the integrity of the original documentation while clearly indicating that certain information is no longer valid. This method ensures that any information remains traceable for reference, which is important for safety and accountability in air traffic control operations.

By marking out information with an "X," controllers are able to provide a clear visual indication that the data was previously valid but is now superseded or cancelled. This practice helps prevent confusion and ensures that all personnel can easily understand the current status of the flight without completely removing the context of what was previously noted.

The other options—writing over existing information, cutting out portions of the strip, or discarding the strip—do not provide this level of clarity or accountability. Writing over information can create ambiguity, while cutting or discarding strips may lead to loss of valuable historical data. Therefore, using an "X" represents the most effective and recommended practice in the management of flight progress information.