- A flight is uniquely identified by an airline and flight number.
- A flight is made up of one or more flight legs, each of
which has a length.
- For each flight leg, there is a departure airport and an
arrival airport (required). There is also a scheduled departure time
and a scheduled arrival time.
- A flight leg can have any number of associated
instances. A particular instance has actual departure and
arrival information (time and airport; airport is required)
on a particular day and has been assigned a particular
airplane (required). A flight leg instance is uniquely
identified by the date, departure and arrival airport codes,
airline, and flight number.
- An airport is uniquely identified by a code, and also has a
location consisting of the airport's name and the city and state
where it is located.
- A type of airplane is uniquely identified by its maker and
model. It also has a range (how far it can fly). Certain kinds
of airplanes can only land at certain airports.
- A particular airplane is of a particular type (required)
and is uniquely identified by its ID.