Definition
The published bearing of an RNAV airway or route, measured in degrees from magnetic north, calculated at the route's point of origin. It is a fixed, charted value that does not change along the length of the route, even though actual magnetic variation may differ slightly at points further along.
Plain English
A single direction printed on the chart for an RNAV route, given in degrees from magnetic north and measured at the start of the route. It stays the same the whole way, so pilots and controllers always refer to one number for that route.
Context Anchor
Seen on IFR en route low altitude charts when a charted point is identified or referenced by a direction from a known navigation point.
Derivation
Magnetic' refers to magnetic north (the direction a compass points). 'Reference' here means a fixed value used as a standard, not recalculated along the way. 'Bearing' is a direction measured in degrees. Together: a fixed magnetic direction used as the standard reference for a route.
Why Pilots Care
Lets pilots read the chart and fly the compass heading without first converting from true north.
Intuition Check
Do not read “bearing” here as a general idea or a piece of equipment. In this context, it means a measured direction from a known point. Do not read “reference” as an instruction to fly it. It means the bearing is being used to identify or locate something on the chart.
Example Sentence 1
The pilot noted the magnetic reference bearing of 087 degrees printed beside the Q-route on the en route chart.
Example Sentence 2
The pilot turned to the magnetic reference bearing listed on the chart to stay on the airway.