Navigation part 1

Question 1

Heading

Answer 1

compass direction which the aircraft is pointing

Question 2

Wind velocity

Answer 2

speed and direction of the wind relative to the surface of the earth

Question 3

Ground speed

Answer 3

aircraft speed relative to the surface of the earth

Question 4

Course

Answer 4

the required ground trace to a waypoint or beacon

Question 5

Track

Answer 5

the path traced on the surface of the earth by aircraft vertically overhead

Question 6

Bearing

Answer 6

magnetic direction to a given object/location

Question 7

Waypoints

Answer 7

predetermined geographical reference point defined by latitude and longitude coordinates ground-based beacons used to indicate fly-by or fly-over information and change in direction

Question 8

Navigation systems

Answer 8

short or long-range - ground station-based systems global coverage - satellite systems autonomous-air data and/or inertial systems

Question 9

Radio navigation aids and communication frequency bands

Answer 9

HF-high frequency VHF- very high frequency UHF- ultra high frequency

Question 10

HF

Answer 10

3-30MHz beyond line of sight long-range communications via skywave propagation(ionospheric refraction)

Question 11

VHF

Answer 11

30-300MHz line of sight VOR-navigation beacons instrument landing systems civilian communications

Question 12

UHF

Answer 12

300-3000MHz line of sight DME-navigation beacons global navigation satellite systems military communications

Question 13

Limitations of short range navaids

Answer 13

• performance is relatively consistent-not affected by ionospheric variation
• subject to the line of sight limitation of VHF communications
  
  • Line of sight range nautical miles (nm) = 1.23√h1(ft) + 1.23√h2(ft)
• significant infrastructure required
• considerations of dessert or oceanic crossings

Question 14

VOR

Answer 14

VHF omnirange VOR uses VHF for bearing pilot tunes navigation receiver into the VHF frequency ground station radiates 2 signals on VHF band phase difference between signal provides the radial on which the aircraft flies

Question 15

DME

Answer 15

DME uses UHF for range but is frequency paired the user selects only VOR/UHF frequency to get both range and bearing transponder based aircraft equipment DME unit interrogates the ground station and measures the time to reply

Question 16

GPS system

Answer 16

control - ground stations providing monitoring and control space- satellites user - GPS receivers, any number of users

Question 17

GPS principle

Answer 17

receiver system knows position of all satellites GPS receivers measure Time of Arrival and receives Time of Transmission of signals from 4 satellites and from this, the Time of Flight values are computed 3D position of the aircraft and offset of receiver clock are computed simultaneously using the navigation equations At lease 4 satellites are required to resolve 4 equations

Question 18

GPS Augmentation

Answer 18

augmentations ar methods used to improve the reliability, accuracy and availability of the system by considering the integration of external information into the calculations

Question 19

ABAS- aircraft based augmentation

Answer 19

receiver autonomous integrity monitoring(RAIM) uses redundant satellites to monitor and predict actual performance improves accuracy, reliability and availability of GPS navigation absolute minimum in GPS aircraft navigation

Question 20

External augmentation- differential GPS concept

Answer 20

correction signals are derived from the difference between the GPS computed positions of ground stations and their actual surveyed locations stations broadcast the difference between the measured and actual pseudoranges GPS users correct their pseudoranges according

Question 21

SBAS satellite based augmentation

Answer 21

corrections over large areas allow aircraft to rely on GPS for all phases of flight including approaches on runways network of ground reference stations measure variations in signal master stations send deviation corrections to SBAS satellites for broadcast to users high accuracy high integrity high availability

Question 22

GBAS- ground bases augmentation

Answer 22

corrections over a small area allows precision GPS instrument approaches GLS which can be used in all weather conditions it is based on real-time differential correction of the GPS signal within a local area corrections are sent via VHF data link on ILS freq ~110MHz

Question 23

Other GNSS

Answer 23

GLONASS - russian system GALILEO-European system planned for operation in 2020 low precision position for free high precision for commercial users with 1m precision transponder function to relay distress signals from emergency beacons

Question 24

Autonomous nav aids

Answer 24

inertial navigation initialised with aircraft lat/long. coordinates / GPS position at parking position in departure airport inertial sensors accelerometer gyro measurements relative to the inertial frame

Question 25

Rigid platform

Answer 25

IRS fixed to airframe, measurements from the body frame solid state components Ring laser gyro used increased accuracy and reliability compared to rotating gyro

Question 26

Stable platform

Answer 26

gyros control gimbal servos platform axis remains fixed in space accelerometers and gyros mounted on the platform

Question 27

INS characteristics

Answer 27

dead reckoning navigation autonomous and self contained high update rates 100MHz no external interference indirect position, velocity and altitude very accurate but accuracy drifts with time

Question 28

GNSS characteristics

Answer 28

relies of satellite availability susceptible to jamming/RF interference accuracy