Using a data flow diagram, capture the data and functional requirements for monitoring the entry, exit, and traversal of planes in an airspace. Planes entering the space are sensed by the Radar input; the Comm input identifies planes that leave the space.

The current contents of the space are maintained in the data area AirspaceStatus.

A log or history of the space is kept in the AirspaceLog storage. An air traffic controller can request the display of the status of a particular plane through the

Controller} input.