Radionavigation Procedures

Chapter 18.22

Cross Bearing

To determine the position of the aircraft without DME, RNAV, INS or GPS, the cross bearing method is used. However, this requires at least two radio beacons.
The own position is the intersection of the two radials/QDRs. The precision of this measurement is highest when the two radials are at right angles to each other and the beacons are not far apart.

Homimg

To reach a beacon (NDB or VOR), the aircraft is turned to the actual QDM or to the actual radial +180°.

Procedure NDB

• Determine the actual QDM
• Turn the aircraft on the shortest way to the course of the actual QDM.
• After the turn, you have a QDM that has changed by a few degrees.
• Turn the aircraft to the new QDM.

Homing Procedure VOR

To reach a beacon (NDB or VOR), the aircraft is turned to the actual QDM or to the actual radial +180°.

Procedure VOR

• Determine the actual Radial +180° (turn the Course Selector until the Deviation Bar is centred and the TO/FROM indicator shows TO).
• Turn the aircraft on the shortest way to the course of the actual radial +180°.
• After the turn, turn the Course Selector until the Deviation Bar is fully centred again and the TO/FROM display still shows TO (actual radial +180°).
• Turn the aircraft to the new value (actual radial +180).

Corrections Inbound

The corrections during the onward flight to the station are made according to the «double deviation» principle.

Procedure NDB

• Determine the actual QDM / ACTUAL QDM
• Calculate the difference between the actual QDM / ACTUAL QDM and requested QDM / REQUESTED QDM.
• Correct with the double difference by « pushing» the needle onto the REQUESTED QDM until the REQUESTD QDM is displayed.

Corrections Inbound VOR

The corrections during the onward flight to the station are made according to the «double deviation» principle.

Procedure VOR

• Determine the deviation of the COURSE DEVIATION BAR (outermost mark = 10°)
• Correct your heading with the double deviation in the direction of the COURSE DEVIATION BAR until it is centred again.

Overflight of a Station

NDB
In the immediate vicinity of the station, the display begins to fluctuate strongly.
During the overflight, the display flips and then points backwards.

VOR
In close proximity to the station, the display (incl. TO/FROM) begins to fluctuate strongly. In this phase, no more corrections are made. During the overflight of a station, we move for a moment into the zone in which the VOR is not received (cone of silence).
Depending on the device, this is indicated by a red warning (no reception). After the overflight, the new radial is intercepted. This is done according to the following principle for both VOR and NDB.

Overflight of a Station (NDB)

Procedure NDB:

• Before overflying the station, determine the difference between the current QDM (up to the station) and the REQUESTED QDR after overflying the station.
• Determine the intercept angle: divide the difference by 3 (maximum 30°).
• The Intercept HEADING corresponds to the Requested QDR ± the Intercept Angle.
• After the station pass, «drag» the needle with the Intercept Angle to the Requested QDR.

Overflight of a Station (VOR)

Procedure VOR:

• Before overflying the station, determine the difference between the previous radial +180° (track to the station) and the REQUESTED RADIAL after the station.
• Determine the intercept angle: divide the difference by 3 (maximum 30°).
• The Intercept HEADING corresponds to the Requested RADIAL ± the Intercept Angle.
• Immediately after crossing the station, turn the Course Selector to the Requested RADIAL. Correct with the Intercept Angle in the direction of the Course Deviation Bar.

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Corrections Outbound

The corrections during the onward flight from the station are made according to the «double deviation» principle.

Procedure NDB

• Determine the current QDR / ACTUAL QDR
• Calculate the difference between the current QDR / ACTUAL QDR and requested QDR / REQUESTED QDR.
• Correct with the double difference by «dragging» the needle to the REQUESTED QDR until the REQUESTD QDR is displayed.

Corrections Outbound VOR

The corrections during the onward flight from the station are made according to the «double deviation» principle.

Procedure VOR

• Determine the deviation of the COURSE DEVIATION BAR (outermost mark = 10°)
• Correct your heading with twice the deviation in the direction of the COURSE DEVIATION BAR until it is centred again.