Avionics Multiple Choice Questions on “Guidance and Navigation”.
1. What is the number of components of the vector that describes the translational motion of the vehicle?
a) 6
b) 3
c) 2
d) 1
Answer: a
Clarification: The three components of position and the three components of velocity make up a six component state vector that fully describes the translational motion of the vehicle.
2. What is the process called when the state vector is calculated on board the vehicle?
a) Navigation
b) Guidance
c) Surveillance
d) Position location
Answer: a
Clarification: When the state vector is measured and calculated on board, the process is called navigation. When it is calculated outside the vehicle, the process is called surveillance or position location.
3. Which type of navigation measure the state vector without regard to the path travelled by the vehicle in the past?
a) Dead reckoning
b) Positioning
c) Direct reckoning
d) AHRS
Answer: b
Clarification: Navigation systems can be categorized as positioning or dead reckoning. Positioning systems measure the state vector without regard to the path travelled by the vehicle in the past.
4. Which one of the following does not fall under the positioning system?
a) Radio systems
b) Celestial systems
c) AHRS
d) Mapping navigation systems
Answer: c
Clarification: There are three types of positioning systems radio systems, celestial systems and mapping navigation systems. AHRS or Attitude Heading Reference System use accelerometer and gyroscope and hence fall under the dead reckoning navigation system.
5. Dead reckoning systems must be re-initialized as errors accumulate.
a) True
b) False
Answer: a
Clarification: Dead reckoning systems use gyroscope and accelerometer whose readings suffer from drift error as time progresses. Thus it is necessary to reinitialize after a particular time interval as errors accumulate and if the electrical power is lost.
6. Which of the following navigational systems is most stealthy?
a) Secondary surveillance radar
b) VOR
c) Celestial navigation
d) SONAR
Answer: c
Clarification: In celestial navigation, the position is computed by measuring the elevation and azimuth of celestial bodies relative to the navigational coordinate frame at precisely known times. Since it is a completely passive system, it is considered to be stealthy and is used in special purpose high altitude aircraft in conjunction with an inertial navigator.
7. How is the velocity of an aircraft measured by passive radio systems?
a) Doppler shift
b) Velocity data is transmitted by the aircraft and received by the station
c) Secondary surveillance method
d) Satellite mapping
Answer: a
Clarification: The aircraft’s velocity is measured from the Doppler shift of the transmission or from a sequence of position measurements. Since the aircraft is continuously moving, each interrogation pulse when it is received will have different phase shift which corresponds to the aircraft’s velocity.
8. Any type of dead reckoning system is independent of radio waves.
a) True
b) False
Answer: b
Clarification: There are two types of dead reckoning navigation system one uses the gyroscope and accelerometer while the other depends on radio stations that create continuous ambiguous radio lanes that must be counted to keep track of the course position.