05non Directional Beacon

8/3/2019 05non Directional Beacon

1/10

NONNON--DIRECTIONALDIRECTIONAL

BEACONBEACONNDBNDB


2/10

GROUND BASED EQUIPMENTGROUND BASED EQUIPMENT

NDBs are rarely found in the US, But stillcommon in Canada.

Used in busier areas as a means of identifying

approach fixes (ILS), and as a sole means ofnavigation and approach in remote areas.(unless equipped with GPS)

NDB facilities are relatively inexpensive to build

and maintain. NDB simplicity is its greatest strength.

Essentially an AM radio transmitter.


3/10

AIRCRAFT EQUIPMENTAIRCRAFT EQUIPMENT

Receiver

Control Head

Indicator(Automatic Direction Finder)

Fixed Card relative bearing or magnetic bearing Radio Magnetic Indicator (RMI) magnetic bearing

The head of the needle always points to the station.

Two Antennas Sense non-directional signal

Loop directional signal (180 ambiguity withoutsense)

Note: see propilot simulation


4/10

OPERATIONOPERATION

The desired frequency is tuned.

The station is identified.

ANT setting may be used to identify station, but

no directional information will be available, ADFmust be selected prior to navigation.

ADF equipment has no flag system to indicatereception, therefore pilots must monitor theaudible identifier of the station anytime ADF is

the sole means of navigation and throughout theapproach phase of flight. Note: some EFIS displays incorporate a flag warning

system, making audio monitoring unnecessary.


5/10

SELKIRK AVIATION SOP 2.8.11SELKIRK AVIATION SOP 2.8.11

Monitoring ADF Audio

When IFR or simulated IFR and navigating by ADF,

the ADF audio identifier will be monitored during all

NDB instrument departures and approaches. Whennavigating enroute with ADF only, pilots should check

the Morse code identifier frequently to confirm the

station is still working.

When flying GPS overlay approaches that have been

properly setup from the database it is not necessary

to monitor ADF audio.


6/10

ERRORSERRORS

Bank Error needle will point down to thestation when aircraft is banked.

Quadrantal error Caused by therefraction (bending) of the incoming radiowaves by the aircraft structure.

Minimum when station is off cardinal points(nose, tail, or wingtip).

Maximum in between.


7/10

LIMITATIONSLIMITATIONS

Skip Zone: an area of erratic indication or signalloss between the points where the ground waveends and the sky wave hits the ground.

Night Effect: occurs at night due to thereception of sky waves reflected by theionosphere. It is most pronounced at sunriseand sunset. Has a greater effect on higherfrequencies. More pronounced further from the

station. Fading: similar to night effect although theerratic indications are caused by out of phasesignals.


8/10

Shoreline Effect: water and land havedifferent levels of conductivity causing thesignal to bend as it crosses a shoreline.

(most pronounced at angles of less than30 with the shoreline; accounted for onpublished airways.)

Terrain: mountains and natural magneticdisturbances effect signals. (accounted foron published airways.)


9/10

Interference: if an ADF receives twosignals it will alternate back and forthbetween them until one becomes

dominant. (needle will swing back andforth.)

Thunderstorms: electrical disturbances

cause static interference and erroneous orerratic indications. The needle willsometimes point towards the storm.


10/10

ACCURACYACCURACY

Systems are flight checked to an accuracy

of at least +/- 5 for approach and +/- 10

for en route. The accuracy of an NDB at

any given time is difficult to determine

when considering all the factors creating

errors. However the accuracy will be

adequate for the purpose intended. (en-route 50-75nm range, approach 25nm

range.)

Documents

05non Directional Beacon