FIGURE $5-14$ Relationships for Assign Flight Request Subsystem ERD.

The data model also shows that a Flight Request Notification entity instance notifies one

Pilot entity instance, and that related Pilot instance must exist. A Pilot entity instance may be

notified by many Flight Request Notification entity instances, and a Pilot entity instance does

not require that a related Flight Request Notification entity instance exist. The business model

that Dr$$nTeq is using expects that pilots will enter the partnership program and will establish

accounts before ever receiving notices of potential flights to perform, so these business rules

seem appropriate.