Bearing And Direction

QDM, QDR, QTE, and QUJ, which are all Q-codes used in radio navigation (especially with VORs, RMIs, and ADFs). They describe bearings and directions between the aircraft and the navigation beacon.

Example Using VOR + RMI

Imagine:

Aircraft heading 090° (east)
RMI needle points 45° to the right (so station is at 135° relative bearing)
Magnetic variation = 10°E

Then:

Term	Meaning	Value
QDM	Magnetic bearing to station	090° (heading) + 135° (relative) = 225°M
QDR	Magnetic bearing from station	225° + 180° = 045°M
QTE	True bearing from station	045° + 10° = 055°T
QUJ	True bearing to station	225° + 10° = 235°T

✈️ Summary Table

Code	Meaning	Reference	Direction	Example
QDM	Magnetic bearing to the station	Magnetic North	To station	045°
QDR	Magnetic bearing from the station	Magnetic North	From station	225°
QTE	True bearing from the station	True North	From station	235°
QUJ	True bearing to the station	True North	To station	055°

The VOR system itself is referenced to the beacon’s magnetic variation

🔹 1. How a VOR defines direction

Every VOR station transmits radials that are defined with respect to magnetic north at the VOR’s location.

The line from the VOR to the aircraft is at 090° magnetic, measured using the magnetic variation at the VOR — not at the aircraft.

🔹 2. The OBS on your aircraft

When you rotate the OBS (Omni Bearing Selector) to select a course, the VOR receiver in your aircraft is interpreting your selection relative to the VOR’s magnetic frame.

So even though your aircraft’s compass may have a different local variation, the course indication (TO/FROM) and the radial information are both based on the beacon’s magnetic reference.

🔹 3. Therefore…

Both QDR (bearing from the station) and QDM (bearing to the station) are referenced to the same magnetic meridian — that of the VOR station.

✅ Hence, they are reciprocals:

$$ QDR = QDM ± 180° $$

no matter what the local variation is at your aircraft’s position.

VOR radial lies along a great circle (or very close to it), but its representation on a chart can make it look otherwise depending on the map projection.

A VOR radial is a line from the VOR station extending outward at a fixed magnetic bearing, measured clockwise from magnetic north at the station.

In geometry terms, it’s the shortest path between the VOR and any point on that line — and thus, it follows a great circle path across the Earth’s surface.

Each VOR radial = a great circle line starting at the beacon.

Bearing

Bearing is the direction or angle from one point to another, measured clockwise from a reference north (true, magnetic, or grid north).

So, it tells you “which way to look or travel” from your current position to reach something else — like a beacon, runway, or waypoint.

Types of Bearings

Type	Reference	Used For	Example
True Bearing	Measured clockwise from True North (geographic north pole)	Charts and maps	045°T
Magnetic Bearing	Measured clockwise from Magnetic North (where your compass points)	VOR, ADF, compass headings	050°M
Grid Bearing	Measured from Grid North (used on polar charts)	High-latitude operations	048°G
Relative Bearing	Measured clockwise from the aircraft’s nose (heading = 000°)	ADF/RMI needle indication	045°R

Bearings vs Headings vs Tracks

Term	Definition	Key Point
Bearing	Direction to or from an object	Measured from north
Heading	Direction the aircraft’s nose is pointing	Affected by wind drift
Track	Actual path over the ground	May differ from heading due to wind

So:

Bearing tells you where something is.
Heading tells you where you’re pointing.
Track tells you where you’re actually moving.

Relation to Navigation Aids

VOR: The radial you’re on is the magnetic bearing from the VOR (QDR).
ADF/NDB: The pointer gives the relative bearing; adding your heading gives the magnetic bearing to the beacon (QDM).
RMI: Combines heading + bearing so the needle directly shows the magnetic bearing to or from the station.