Navigation Flashcards
What is the general definition of air navigation?
The process or method with which an ACFT is guided safely from its starting to point to its destination. This involves determining the position of the ACFT, monitoring its flight path and making any necessary corrections.
What are the 5 main components of navigation?
Position, Course, Distance, Time and Altitude
What are the 4 methods of air navigation?
- Visual navigation
- Dead reckoning navigation
- Radio navigation
- Area navigation which includes inertial navigation, VOR/DME, DME/DME, Satellite navigation and LORAN C
Approximately how many kilometres does the Diameter of the earth differ from pole to pole to measuring at the equator?
42km
What is the mean circumference of the earth in km and NM?
- 40000 km
- 21600 NM
What is the rotational speed at the equator?
1670km/hr (900kts) - 15 degrees per hour
What is a great circle?
- A circle on the Earth which lies in a plane that passes through the centre of the Earth.
- Route along great circle represents shortest distance on the Earth between 2 points.
- Examples include the equator and all circles of longitude.
What is a Meridian?
- Line of Longitude (great semi-circle) joining the North and South poles.
- Prime Meridian passes through Greenwich - used worldwide since 1884.
What is a small circle?
A circle on the Earth which is not a great circle such as Parallels/Circles of Latitude (Parallel to the Equator)
What is the tilt of the earths axis?
23.5°
What is the Tropic of Cancer?
Parallel of latitude approximately 23.5° North and is the northernmost latitude reached overhead by the sun.
What is the Tropic of Capricorn?
Parallel of latitude approximately 23.5° South and is the southernmost latitude reached overhead by the sun.
Define ecliptic
The name of the plane on which the Earth moves during its orbit around the Sun.
What is a sidereal year?
The orbital period of the earth around the sun, taking the stars as a reference frame. It is 20 minutes longer than the tropical year because of precession.
What is a tropical year?
365.25 days
What is a gregorian year?
A year of mean length which results from normal years and leap years (365.2425 days)
When does a day start?
Starts at the lower culmination of the sun. At midday, the sun reaches the upper culmination.
What is a true solar day?
2 successive lower culminations of the sun
What is a mean solar day?
2 successive lower culminations of the mean sun. Its length is constant and equal to the mean length of all true solar days.
What is Local Mean Time (LMT)?
The time at the meridian of the point in question dependent on the geographical longitude only.
What is Zone Time (ZT)?
Division in zones with 15° longitude. The centre meridian defines zone time.
What is Standard Time (ST)/Legal Time (LT)?
Based on the zone time and fulfils legal, political and economic interests.
What is Universal Time Coordinated (UTC)?
Based on international atomic time, kept within 0.9s of UT1 and is closely related to GMT. This is the time used in air navigation all over the world.
What do the actual times of sunrise (SR) and sunset (SS) depend on and where can they be found?
Season and geographical latitude. Times can be found in the AIP.
What is civil twilight?
Begins or ends when the centre of the sun lies 6 degrees below the horizon. The average length is about 40 minutes at 50° latitude.
Why is a magnetic grid not possible
Due to disturbances in many areas and the magnetic north and south poles are not directly opposite.
What is magnetic variation?
The angle between the magnetic meridian and true meridian.
What are isogonic lines?
Lines on a chart which indicate the magnetic variation in a particular area.
What is deviation?
Angles between compass north and magnetic north.
What are the types of map projections?
Conical, cylindrical (Mercator) and azimuthal
What are the properties of lamberts conical projection? (8)
- Meridians - straight lines converging towards the poles.
- Parallels - concentric arcs of circles.
- Great circles - approximately a straight line.
- Rhumb lines - curve towards the equator
- True Scale - sufficient for practical purposes
- True angles - yes
- Distortion - slight
- Use - all types of navigation at medium latitudes
What scale of chart is used for aeronautical charts?
1:500,000
What are the 3 types of vector in the wind triangle?
- Air vector - single red arrow (Shows heading and TAS)
- Ground vector - double green arrow (Shows track and GS)
- Wind vector - triple blue arrow (Shows wind direction and speed)
What types of speed are used in air navigation? (7)
IAS, CAS, EAS, TAS, Wind speed, GS and Mach number
What do ATC use IAS for?
Applying speed control
What is mach number and when is it applied?
The ratio of TAS to the local speed of sound. Its used for speed control above FL245
What is the difference between upper wind and surface wind with regards to direction?
Upper wind direction is given in degrees true.
Surface wind is given in degree magnetic.
What is the drift angle (DA)?
Angle between heading and track.
What is the wind correction angle (WCA)?
Angle between the desired track and heading (equal but opposite to the DA)
What is the wind angle (WA)?
Angle between ground vector and wind vector
What is the relative wind angle (RWA)?
Angles between the air vector and wind vector
How is the Maximum Elevation Figure (MEF) determined on a chart?
Either:
- Highest obstacle + 60ft rounded to the next 100ft.
or
- Highest elevation + 358ft rounded to the next 100ft.
What is the true heading?
Angle between true north and ACFT longitudinal axis.
What is the true track?
Actual flight path over the surface of the earth.
What is the relative bearing?
Angle between ACFT longitudinal axis and bearing.
What is the true bearing?
Angle between true north and bearing.
equal to true heading + relative bearing.
What is QDM and QDR?
QDM - Magnetic bearing to station.
QDR - Magnetic bearing from station.
What is QUJ and QTE?
QUJ - True bearing to station.
QTE - True bearing from station.
What are 3 type of indicator for an ADF?
RBI - Relative Bearing Indicator.
MDI - Moving Dial Indicator.
RMI - Radio Magnetic Indicator.
What can an ADF be used for?
NDB navigation using homing and tracking.
What happens to the to and from flag when an ACFT passed over the VOR cone of silence?
It flips back and forth
What happens to the DME indication when passing over the DME cone of silence?
It will freeze at the last recorded slant range and unfreeze on exiting the cone of silence.
When is the only time the groundspeed on the DME display reliable?
When the ACFT is tracking directly to or from the station
At 60NM range fro a station, what does track angle error of 1 degree represent?
1NM cross track.
What is an instrument approach?
A series of predetermined manoeuvres by reference to flight instruments with specified protection from obstacles from the IAF, or where applicable, from the beginning of a defined STAR, to a point from which a landing can be completed and thereafter, if landing is not completed, to a position at which holding or enroute obstacle clearance apply.
What are the precision approaches? (5)
ILS MLS GLS (GBAS landing system) PAR (Precision Approach Radar) GNSS with SBAS CATI
What are the additional 2 approaches with vertical guidance (APV)? (2)
GNSS with Baro-VNAV
GNSS with SBAS
What are the non-precision approaches? (6)
LOC VOR NDB GNSS SRA (Surveillance Radar Approach) TACAN
What is a 2D approach classification and a 3D approach classification?
2D - Use lateral guidance only
3D - Use both lateral and vertical guidance
What is the decision height/altitude with reference to?
THR Elev
What is the minimum descent height/altitude (MDA) with reference to?
AD Elev or THR Elev (If THR is more than 7ft below AD Elev)
What are the miscellaneous classifications of instrument approaches?
Standard, vectoring, straight in and circling
What are the classifications of instrument approaches by lowest operating minima?
Type A: MDH or DH at or above 250ft
Type B: A DH below 250ft (Further categorised below)
CAT I:
- DH not lower than 200ft
- Either visibility not less than 800m or RVR not less than 550m
CAT II:
- DH lower the 200ft but not lower than 100ft.
- RVR not less than 300m
CAT III (sub divided into IIIA, IIIB and IIIC):
CAT IIIA:
- DH lower than 100ft but not less than 50ft
- RVR not less than 200m
CATIIIB:
- DH lower than 50ft or no DH
- RVR less than 200m but not less than 50m
CATIIC:
- No DH or RVR limitations
What are the approach categories and what are they based on?
A: < 91kt IAS B: 91kt ≤ IAS 121kt C: 121kt ≤ IAS < 141kt D: 141kt ≤ IAS < 166kt E: 166kt ≤ IAS < 211kt H: Helicopters (May use category A)
Based on the velocity at THR with 1.3 x stall speed in the landing confit at the MAX certified landing mass.
How many instrument approach segments are there and what are these?
5:
- Arrival route, initial approach, intermediate approach, final approach and missed approach.
What is the Minimum Obstacle Clearance (MOC) for the arrival and initial approach segments?
300m
What is the Minimum Obstacle Clearance (MOC) for the intermediate approach segment?
150m
What is the Minimum Obstacle Clearance (MOC) for the final approach segment?
Reducing to OCH
What is the Minimum Obstacle Clearance (MOC) for the missed approach segment?
300m
What are the 3 methods of designing an initial approach with only 1 ground station?
Procedure turns, base turns and racetrack procedures
For a PA what is the OCH/A with reference to?
THR Elev
For a NPA what is the OCH/A with reference to?
AD Elev or THR Elev (if THR more than 2m below AD Elev)
For a circling approach what is the OCH/A with reference to?
AD Elev
What is area navigation?
Method of navigation which permits ACFT operation on any desired flight path within the coverage of ground or space based navaids or within the limits of the capacity of self contained aids (INS/IRS), or a combination of these.
An ACFT can fly between any 2 points (defined by LatLong coords) whatever their distance. Track deviation is know and expressed in terms of distance.
What are the benefits of area navigation? (5)
- Increased safety
- Navigational flexibility
- Shorter routes/reduced time en-route
- Less fuel usage
- Reduced workload for both flight crews and ATCOs
What is a waypoint?
A specified geographical location used to define an area navigation route or the flight path of an ACFT employing area navigation.
There are 2 types, fly over (used in terminal area only) and fly by (used in both en-route and terminal area).
What are the factors which influence turn anticipation?
- The amount of turn to be made.
- The GS of the ACFT.
- ACFT bank angle limitations
- The type of ACFT and/or FMS combination
What are the type of RNAV systems?
- VOR/DME (position by direction and distance)
- DME/DME (position by 2-3 DME stations)
- GNSS (GPS, GLONASS, Galileo and BeiDou)
- ILS
- INS
- LORAN
What are the 3 major GPS Segments?
- Space segment
- Control segment (On the ground)
- User segment (system with the user)
What do the following terms mean on a GPS display? DIS, DTK, BRG, GS, TRK, ETE, XTK
- DIS - Distance (Great circle distance)
- DTK - Desired track
- BRG - Bearing
- GS - Groundspeed
- TRK - Track
- ETE - Estimated time en-route
- XTK - Cross track
How many satellites are required for a 3D position?
4
How many satellites are required to use GNSS as a standalone system?
At least 6
What do the following terms mean on an INS display? TK, GS, XTK, TKE, POS, WPT, DIS, TIME, WIND, DSR TRK, STS
- TK - Track
- GS - Groundspeed
- XTK - Cross track
- TKE - Track angle error
- POS - Position
- WPT - Waypoint
- DIS - Distance
- TIME - Time to waypoint
- WIND - Direction and speed
- DSR TRK - Desired track
- STS - Status
How does the FMS calculate the ACFTs position?
- Primarily by using the INS/IRS to obtain MIX IRS position.
- This is then updated by GNSS.
- If GNSS is unavailable, MIX IRS may be updated using radio navigation ie DME/DME, VOR/DME, LOC in this order of priority.
- IRS only is used if no GNSS or radio navaids are available.
Name an area navigation system which is autonomous
INS/IRS
Which RNAV system will provide the highest position accuracy?
GPS (GNSS)
Which ground based sensor offers the highest position accuracy?
DME/DME
What is the primary purpose of the FMS?
Navigation by integration of all other navigation systems - To compute ACFTs position as accurately as possible.
What is EPU?
Estimated Position Uncertainty - continuously calculated by the FMS to estimate how much FMC position has diverged.
This is compared with the Required Navigational Performance (RNP).
What is PBN?
Performance Based Navigation: Area navigation (RNAV) based on performance requirements for ACFT operating along an ATS route, on an instrument approach procedure or in a designated airspace.
Expressed in terms of accuracy, integrity, continuity and functionality needed for the proposed operation.
LNAV only for the time being
What three components does Performance Based Navigation (PBN) comprise of?
Navigation Application:
- ATS routes
- Free Route Airspace
- Departure Procedure
- Arrival Procedure
- Instrument Approach Procedure
Navigation Specification:
- RNAV5
- RNAV1
- RNP Approach
Navigation Infrastructure:
- VOR
- DME
- Satellite Navigation System and augmentation systems
- Communication
- Surveillance
What are the main benefits of PBN?
- Improved safety
- Improved operating returns
- Increased airspace capacity
- Environmentally friendly
What is the main difference between RNAV and RNP specifications?
On board performance monitoring and alerting is required for RNP.
With regards to RNP, what does on board performance monitoring and alerting detect?
System degradation below an integrity level of 10^-5 or that the integrity level of 10^-5 cannot be guaranteed.
Note: Permits closer route spacing and has better integrity than RNAV.
What are the advantages of RNP over RNAV?
- Operation up to a Total System Error (TSE) of 0.1NM (RNP0.1).
- No surveillance or voice communication required.
- Curved segments (radius to fix) and approach procedures are possible.
What is TSE?
Total System Error - the sum of Path Definition Error (PDE), Navigation System Error (NSE) and Flight Technical Error (FTE).
