Definition
The specific radio aids, satellite signals, or other navigation inputs selected for a flight, together with the desired tracks (courses) set on the cockpit navigation instruments. During the before-takeoff check, the pilot confirms that the correct navigation source is chosen for each instrument and that the courses set match the planned route of flight.
Plain English
The navigation signals you're going to use during the flight, and the direction lines you've set on your instruments to follow. Before takeoff, you make sure the right signal is selected and the right direction is dialed in.
Context Anchor
Checked during the before-takeoff checklist when the pilot confirms that the panel, map display, or navigation indicator is set up correctly for the planned flight.
Derivation
Navigation comes from Latin words connected with ships and sailing. Course comes from a word meaning a run or a path. Together, the phrase points to both parts of the task: where the guidance comes from, and what path it is set to follow.
Why Pilots Care
Wrong selections can cause immediate track deviations or loss of situational awareness in the critical moments after liftoff.
Intuition Check
Do not read source as a textbook source, and do not read course as a class. Here, source means the equipment or signal giving navigation information, and course means the selected path or direction to fly.
Example Sentence 1
During the before-takeoff check, the pilot verified the navigation sources and courses, confirming the GPS was selected on the primary display and the first course was set to 270 degrees.
Example Sentence 2
The student was instructed to recheck all navigation sources and courses after loading the flight plan to prevent an initial heading error.