Nav aids Flashcards
What’s an NDB’s use?
Show the direction of the NDB in the cockpit on the ADF needle.
What are the 5 classes of VDF and their accuracy?
- Class A +/- 2 degrees
- Class B +/- 5 degrees
- Class C +/- 10 degrees
- Class D > 10 degrees
- Digital resolution direction finding (DRDF) +/- 1 degree
What is GPS?
Global positioning system is a precision 3D area navigation aid. It obtains multiple fixes from orbiting satellites. Its accuracy is 100m for civil and 1-3m for military and is range is global. If GPS satellites are u/s NOTAMS are issued.
What are the 3 limitations of VOR?
- Provides no distance info
- Large site required
- Expensive to build and maintain
What does DME stand for?
Distance measuring equipment
What are the 7 limitations of NDBs?
- Static effect
- Night effect
- Station interference
- Coastal refraction
- Mountain effect
- Quadrantal error
- Absence of failure warning
What does VOR stand for?
VHF omni-directional range
What des NDB stand for?
Non-directional beacon
What does ILS stand for?
Instrument landing system
How does and NDB work?
A radio transmits in all directs and can be picked up by the a/c and shown by the ADF needle. Runs on MF and has a max range of 50nm in the UK (more power = more range).
What does a DME do?
Provides an accurate measure of distance from the a/c to the beacon by interrogating the transponder. Not usually stand alone often added to VORs, ILS or NDBs. They’re a secondary radar system as they can differentiate a/c.
What is a limitation of DME?
Inaccuracy caused by slant range.
What is the arrival segment of an instrument approach?
The a/c routes from the en-route phase to an initial approach fix.
What does a VOR do?
Shows the direction to or from the VOR.
What are the 5 ILS categories, their RVR and decision heights?
- CAT I 550m 200ft
- CAT II 250m 100ft
- CAT III a 200m Nil
- CAT III b 50m Nil
- CAT III c 0m Nil
What does VDF stand for?
VHF direction finding
What is height in reference to?
The height above a fixed point on land e.g. the runway.
What is altitude in reference to?
The altitude above mean sea level (MSL)