DME, ILS & GNSS (GPS) Flashcards
DME uses the ____ principle based on SSR.
DME uses the transponder principle based on SSR
DME operates in the ____ frequency band
UHF
DME readouts give (ground, earth, straight, slant, triangle) range between the aircraft and ground station
What is the correct answer?
give **slant **range between aircraft and ground station
DME channels are normally paired with a ____ or ____
paired with a **VOR **or ILS
When tuning in a DME paired with a VOR you would normally tune the (VOR, DME, NDB, ADF) frequency on the NAV-COM set
What is the correct answer?
normally tune the **VOR **frequency on the NAV-COM set
When a DME is tuned with a paired VOR, two IDENT signals with (the same code, a different code) will be heard. The DME IDENT will be of a (higher, lower) pitch than the VOR IDENT
Which combination gives the correct answer?
When a DME is tuned with a paired VOR, two IDENT signals with **the same code will be heard. The DME IDENT will be of a **higher pitch than the VOR IDENT
If a DME signal is lost, this will be indicated on the display by…
the DME scrolling rapidly from 0nm to 200nm and at the same time the OFF flag or bar/line across the read out will appear
The ground DME transponder can typically provide responses to a max of ____ aircraft at the same time
**100 **aircraft
Describe DME saturation
**When the ground DME transponder is trying to provide responses to more than 100 aircraft at the same time it will become saturated and only the strongest signals will be replied to, weaker signals will be ‘unlocked’ **
If TACAN is paired with a VOR it is called _____
VORTAC
Civilian aircraft can obtain (distance and bearing, distance only, no information) from TACAN
What is the correct answer?
Civilian aircraft can obtain distance only from TACAN
DME is designed to have a max range of ____nm at 30,000ft and is line of sight.
200nm
Use the correct formula to calculate expected DME signal range for an aircraft at 32,000ft with a ground DME station elevation of 800ft
**254.81nm
(square root of DME elevation x 1.23 + square root of aircraft height x 1.23)**
State the calculation to find DME/Slant range given Plan/ground range
**First convert aircraft height to nautical miles
(divide by 6076)
Slant range = square root of (plan/ground range²) + (aircraft height in nm²)**
With relation to DME, What is horizontal/plan range and how is it calculated?
**Is the distance over the ground to the DME station
It can be calculated by first converting aircraft height to nautical miles (divide height by 6076)
Plan Range = square root of (slant range²) - (aircraft height in nm²)**
The ILS Localiser signal uses the ____ band
VHF
ILS Localiser frequencies have an **(odd, even) **number after the decimal point
What is the correct answer?
have an odd number after the decimal point
e.g. 110.3, 110.9 etc
ILS Localiser transmitts two beams that overlap. The left beam is at ____Hz and is refered to as the ____ colour, while the right beam is at ____Hz and refered to as the ____ colour
ILS Localiser transmitts two beams that overlap. The left beam is at 90Hz and is refered to as the **Yellow **colour, while the right beam is at 150Hz and refered to as the Blue colour
ILS Localiser coverage is generally limited to?
25nm and to within (+-) 10°of localiser centreline.
A signal can also be received when 17nm out and within (+-) 35° of the centreline
The CDI needle shows displacement from the LOC Centreline, it (does, does not) provide heading information
does not
With regard to ILS Localiser, Each dot on the CDI instrument represents ____°
0.5°
For every nautical mile away from the ILS LOC transmitter, each dot on the CDI instrument (0.5°) represents ____ft left or right of the LOC centreline
50ft
ILS Glideslope uses the ____ band
UHF
Like the ILS Localilser, the Glideslope signal also uses two lobes of 90Hz and 150Hz and are arranged inclined ____° from the (horizontal, vertical)
What is the correct answer?
inclined 3° from the Horizontal
The overlap of the Glideslope lobes is usually ____° in depth, giving ____° useable coverage above and/or below glideslope
The overlap of the Glideslope lobes is usually 1.4° in depth, giving 0.7° useable coverage above and/or below the glideslope
The standard Glideslope angle is ____°
3°
Max glideslope deflection on the CDI instrument indicates you are ____° above or below a 3° glideslope
Max glideslope deflection on the CDI instrument indicates you are 0.7° above or below a 3° glideslope
Glideslope coverage is calibrated out to a distance of ____nm and generally ____ ° either side of the approach centreline in azimuth
Glideslope coverage is calibrated out to a distance of 10nm and generally 8° either side of the approach centreline in azimuth
To confirm you are on the correct 3° glideslope you could check your descent is ____ft per nautical mile
**300ft **per nautical mile
The instrument showing ILS (LOC & Glideslope) indication is a command instrument, meaning when it deflects above the centre you must (fly higher, fly lower) and if it deflects left from centre you must (fly left, fly right)
The instrument showing ILS (LOC & Glideslope) indication is a command instrument, meaning when it deflects above the centre you must **fly higher **and if it deflects left from centre you must fly left
ILS Marker Beacons are given two names, one is called the ____ marker (OM) and the one closest to the runway threshold is called the ____ marker (MM)
ILS Marker Beacons are given two names, one is called the **outer **marker (OM) and the one closest to the runway threshold is called the middle marker (MM)
When passing overhead an ILS Outer Marker (OM) the indicator in the cockpit will flash what colour?
Blue or Purple
When passing overhead an ILS Middle Marker (MM) the indicator in the cockpit will flash what colour?
Amber
Full deflection of the Locailser CDI needle indicates you are ____° or more either side of the locailser beam
2.5°
Calculate the reference height for a 3° glideslope if you are 6nm out from the runway threshold and the runway threshold has a elevation of 465ft
**2265ft
Multiply distance from runway by 300 then add threshold elevation
e.g. 6nm x 300 = 1800ft + threshold elv of 465ft = 2265ft**
State the calculation to give required ROD to maintain a 3° glideslope at a given groundspeed (G/S)
**G/S x 5 = ROD in ft per min
e.g. 100kts x 5 = 500ft p/m**
To maintain a 3° glideslope approach while at a groundspeed of 112kts, your rate of descent should be?
560ft/pm
State the three main elements/segments of the GNSS system
Space segment
Control segment
User segment
GPS uses two L-bands civilian use is L (1, 2) band and uses the ____.__MHz frequency while Military uses the L **(1,2) **band on the ____.__MHz frequency
What are the correct bands and frequencies used?
GPS uses two L-bands civilian use is L1 band and uses the 1575.42MHz frequency while Military uses the **L2 **band on the 1227.60MHz frequency
State the two types of GPS pseudo-random codes used
**Coarse-Aquisition C/A
Precision P(Y)**
How is GNSS time reference obtained?
Each satellite contains an atomic clock synced with other clocks in the constellation
Describe Ephemeris
Is the data which gives current position of each satellite in its orbit
Describe Almanac with relation to GPS
Is orbital data for the entire GPS constellation and is used by the GPS receiver to predict which satellites will be in view and their estimated ranges on start up.
How is range calculated by the GPS receiver?
The receiver generates the satellites exact same C/A pseudo-random code internally and comparing that with the signal received, time can be calculated and further used to calculate range
State the number of satellites required to obtain a 2D position fix
3
State the number of satellites required to obtain a 3D position fix
at least 4
GPS clock error can be virtually eliminated by the recevier using a process called _____
trimming
RAIM selects only the best ____ or more satellites
4
For RAIM to be operational at least ____ satellites must be in view for RAIM to find a bad satellite and at least ____ must be in view to isolate it
For RAIM to be operational at least 5 satellites must be in view for RAIM to find a bad satellite and at least 6 must be in view to isolate it
Describe GPS receiver masking and why it is used
**Is the function of the GPS receiver to ensure anty satellites in view that lie below a fixed angle of elevation relative to the receiver (or aircraft) are ignored.
It is used to avoid range errors that would generated as the signal travels through the ionosphere and troposphere.**
With regard to GPS receiver masking, the fixed angle set in the receiver is called the Mask Angle and is usually set around ____°
7.5°
How does a GPS receiver predict the position of satellites?
By use of Almanac data stored in the receiver which is constantly updated when the receiver is operating
State the maximum error which could be expected without selective availability (SA) applied
Combined max error is 15-18M, It is the max error to expect 95% of the time
Selective Availability (SA) can cause GPS spherical errors of ____m
**around 100M
(Note: Selective Availability is no longer used)**
State the rules and procedures for RAIM loss while en-route
If RAIM is lost en-route and displayed for more than 10mins or DR mode for more than 1min, ATC must be advised and position verified every 10mins by other approved equipment
It (is, is not) a requirement to obtain RAIM prediction information prior to depature for the destination and destination ETA
is a requirement
Most mapping in NZ uses NZ1949 datum while GPS units use WGS____ datum
WGS84 datum
Inputting coordinates into a GPS unit based on a datum other than WGS84 can cause (no error, minor errors, significant errors of 100s of meters)
significant errors of 100s of meters
describe DGPS
uses ground based fixed stations that broadcast the difference between the position indicated by a GPS satellite and the knwn fixed position of the ground station. It increases accuracy
State at least three errors that can effect GNSS/GPS accuracy
Ephemeris Error
Multi Path Error
Ionosphere Propogation Effects
Troposphere Propogation Effects
Receiver Error
Interference (other devices etc)
