Positioning Flight?

Positioning flights are non-revenue (no paying passengers or freight) flights from where an aircraft is currently located to where it next needs to be.

An example might be an aircraft which has landed and discharged its passenger at LAX and then needs to be flown to SFO for scheduled maintenance. After maintenance, its next scheduled revenue flight is from SEA. The flights between LAX and SFO and between SFO and SEA are positioning flights.

Another example is a case where a scheduled flight has to be cancelled for mechanical failure and where another aircraft is not available at that location to complete the scheduled flight. The movement of another aircraft from somewhere else to pick up the passengers might be a positioning flight.