Avionics - Autopilots and Flight Management Systems Quiz(MCQ)
A)
Better Range
B)
Stable and damped response
C)
Efficient flight
D)
Better climb rate

Correct Answer :   Stable and damped response

Explanation : The height error gain is chosen so that the frequencymax is well below the bandwidth of pitch attitude loop to ensure a stable and well damped height loop response. If the frequency is high, it might lead to oscillations in the vertical axis.

A)
Density of air
B)
Angle of attack
C)
Forward velocity
D)
Aircraft pitch angle

Correct Answer :   Density of air

Explanation : The altitude control loop works using  , Where H is the required height or altitude, θ is aircraft pitch angle and α is angle of incidence.

A)
Engine control
B)
Altitude control
C)
Automated landing
D)
Pitch, roll and yaw control

Correct Answer :   Pitch, roll and yaw control

Explanation : The pitch attitude control loop and the heading control loop, with its inner loop commanding the aircraft bank angle, are thus fundamental inner loops in a common autopilot control mode. They are short, fast period loops which continuously control the control surfaces of an aircraft to maintain the pilot command.

4 .
What is missing in the autopilot loop?
A)
FBL system
B)
FBW system
C)
Autopilot
D)
Flight Management System

Explaination : The basic function of the autopilot is to control the flight of the aircraft and maintain it on a predetermined path in space without any action being required by the pilot. The autopilot can thus relieve the pilot from the fatigue and tedium of having to maintain continuous control of the aircraft’s flight path on a long duration flight so the pilot can concentrate on other tasks and the management of the mission.

A)
Generate commands for the pilot to follow
B)
Generate commands to the inner flight control loop
C)
Access the flight control surfaces to control the pitch and roll of the aircraft
D)
Access the flight control surfaces to control the altitude and heading of the aircraft

Correct Answer :   Generate commands to the inner flight control loop

Explanation : The autopilot exercises a guidance function in the outer loop and generates commands to the inner flight control loop. These commands are generally attitude commands which operate the aircraft’s control surfaces through a closed flight control loop system so that the aircraft rotates about the pitch and roll axes until the measured pitch and bank angles are equal to the commanded angles. The changes in the aircraft’s pitch and bank angles then cause the aircraft flight path to change through the flight path kinematics.

A)
Efficient management of fuel
B)
Management of aircraft systems
C)
Housekeeping management
D)

Explanation : The Light Management System performs various functions such as Automatic navigation and guidance including ‘4D’ navigation, Presentation of information, Management of aircraft systems, Efficient management of fuel, Reduction of operating costs. Housekeeping management is a separate system which takes care of air conditioning, entertainment systems, etc.

A)
Indian Landing system
B)
Indian Levitation System
C)
Instrument landing system
D)
International Levitation system

Correct Answer :   Instrument landing system

Explanation : ILS or instrument landing system is a radio based approach guidance system installed at major airports and airfields where the runway length exceeds 1800 m which provides guidance in poor visibility conditions during the approach to the runway.

A)
ILS
B)
MLS
C)
VHF
D)
SBAS

Explanation : SBAS or Satellite Based Augmentation Systems exploiting differential GPS techniques will be able to provide reliable and accurate approach path guidance in category II visibility conditions. This will be increasingly used in the future.

A)
Localizer transmitter and glide slope transmitter
B)
Center line transmitter and glide slope transmitter
C)
Center line transmitter and approach slope transmitter
D)
Horizontal alignment transmitter and vertical alignment transmitter

Correct Answer :   Localizer transmitter and glide slope transmitter

Explanation : ILS system basically comprises a localiser transmitter and a glide slope transmitter located by the airport runway together with two or three radio marker beacons located at set distances along the approach to the runway. The airborne equipment in the aircraft comprises receivers and antennas for the localiser, glide slope and marker transmissions.

A)
0.5 m
B)
1 m
C)
5 m
D)
10 m

Explanation : The navigation position accuracy of 1 m which can be achieved with the differential GPS technique is being exploited in the US for landing guidance with a system called the Ground Based Augmentation System, GBAS. The Ground Based Augmentation System, when installed at an airport, will be able to provide the high integrity and accurate guidance necessary for landing in Cat. III visibility conditions.

A)
2.91 m/s
B)
3 m/s
C)
3.56 m/s
D)
10 m/s

Explanation : Vertical velocity at the start of flare = approach speed x glide slope angle. Thus Vv= 66.87* x sin(2.5°) = 2.91 m/s . *[converting knots to m/s].

A)
Proportional only
B)
Proportional plus integral
C)
Proportional plus derivative
D)
Proportional plus integral plus derivative

Correct Answer :   Proportional plus integral

Explanation : The auto-flare loop is a high-order system; apart from the lags present in the filtered rad.alt. signals there are also the lags present in the response of the pitch attitude command loop. This loop controls and its response is significantly slower at the low speeds during the approach. A proportional plus integral control term is used in the auto-flare controller to ensure accuracy and some phase advance is generally provided to compensate for the lags in the loop and hence improve the loop stability and damping.

A)
B)
C)
D)

Explanation : The beam error γ = d/R, where d is the displacement of the aircraft’s CG from the beam center line and R is the slant range of the aircraft. γ = 5/1,500 = 0.0033 RAD.

A)
Aircraft range is infinity
B)
When no aircraft is present
C)
Aircraft range is close to zero
D)
When too many aircraft are present

Correct Answer :   Aircraft range is close to zero

Explanation : In the localizer coupling loop gain increases as range between aircraft and runway decreases. The gain reaches a point where it becomes too large and the loop becomes unstable. Thus gain scheduling with range is required.

A)
Flight computer
B)
C)
D)
ILS Localizer transmitter

Explanation : The Localizer coupling loop is integrated with the heading command loop to manage the heading of the aircraft. It is a closed loop system which continuously corrects with respect to the ILS Localizer. The error in flight path is corrected with respect to the localizer beam by means of a localizer receiver in the aircraft.

A)
Runway length
B)
Runway visual range
C)
Decision height
D)
Minimum vertical visibility

Explanation : The two basic parameters used to define the visibility category are the decision height, that is the minimum vertical visibility for the landing to proceed and the runway visual range. The length of a runway is not used to define visibility category.

A)
LF
B)
MF
C)
UHF
D)
VHF

Explanation : The localizer transmitter used VHF range from 108-122 MHz frequency and provides information to the aircraft as to whether it is flying to the left or right of the center line of the runway it is approaching. The localizer receiver output is proportional to the angular deviation γL, of the aircraft from the localizer beam center line which in turn corresponds to the center line of the runway.

A)
LF
B)
MF
C)
UHF
D)
VHF

Explanation : The glide slope or glide path transmission is at UHF frequencies from 329.3 to 335 MHz frequency and provides information to the aircraft as to whether it is flying above or below the defined descent path of nominally 2.5?, for the airport concerned. The glide slope receiver output is proportional to the angular deviation γV, of the aircraft from the center of the glide slope beam which in turn corresponds with the preferred descent path.

A)
Weight of the aircraft
B)
Visibility category
C)
Runway lighting installation
D)
ILS ground installation standard

Correct Answer :   Weight of the aircraft

Explanation : The height limits and visibility conditions in which the autopilot can be used to carry out a glide slope coupled approach to the runway depends on the visibility category to which the autopilot system is certified for operation, the ILS ground installation standard, the runway lighting installation and the airport’s runway traffic control capability.

A)
Category I
B)
Category II
C)
Category III
D)
Category IV

Explanation : Visibility conditions are divided into three categories, namely Category I, Category II and Category III, depending on the vertical visibility ceiling and the runway visual range (RVR). Category III includes zero visibility conditions.

21 .
A)
Direct Height
B)
Decision Height
C)
Distance Height
D)
Direction height

Explanation : This minimum permitted ceiling for vertical visibility for the landing to proceed is known as the decision height or DH. A very high integrity autopilot system is required for fully automatic landing below a DH of 100 ft – Cat. III conditions.

A)
10 ft
B)
25 ft
C)
50 ft
D)
100 ft

Explanation : The auto flare is initiated around 50 ft where the aircraft is over or very near the runway threshold so that the radio altimeter is measuring the height of the aircraft above the runway. Low range radio altimeters are used to ensure accuracy.

A)
1 GHz
B)
1000 MHz
C)
100 MHz
D)
75 MHz

Explanation : The marker beacon transmissions are at 75 MHz. The middle marker beacon is located at a distance of between 1,000 and 2,000 m from the runway threshold and the outer marker beacon is situated at a distance of between 4,500 and 7,500 m from the middle marker.

A)
Decision height of 5m
B)
Runway guidance required to taxi point
C)
Fully automatic landing system with flare
D)
Probability of catastrophic failure of less than 10?7 per hour required

Correct Answer :   Decision height of 5m

Explanation : The autopilot requirements and operational limits for a category III visibility conditions are a probability of catastrophic failure of less than 10−7 per hour, fully automatic landing system with flare, runway guidance required to taxi point. The decision height for a category IIIc condition is 0m. No system is yet certified for category IIIc operation.

A)
Autopilot
B)
FMS
C)
FBW
D)

Explanation : The FADEC or Full Authority Digital Engine Control is a system that controls all aspects of the engine performance. Since there are a lot of variables involved in the control of different engines, the workload of the pilot is increased. The FADEC system is used to reduce the workload at the same time giving full control of the engine to the pilot. It also ensures maximum engine performance at different flight conditions.

A)
Height when flare is initiated
B)
Small negative height
C)
Height where flare should be initiated
D)
Maximum height where flare can be initiated

Correct Answer :   Small negative height

Explanation : In the control law for auto flare, HREF is a small negative height, or bias, which ensures there is still a small downwards velocity at touchdown. This avoids the long exponential ‘tail’ to reach zero velocity and enables a reasonably precise touchdown to be achieved.

A)
Pitot static port
B)
Pitot stagnation port
C)
D)

Explanation : When an aircraft is about to land, accurate altitude measurements are needed. Pitot static measurements suffer from errors due to weather and generally have lag. The aircraft height above the ground is measured by very accurate radio altimeters during the landing phase.

A)
To conserve fuel
B)
To reduce airspeed and rate of descent
C)
To align with the runway
D)
To stabilize the aircraft during crosswinds

Correct Answer :   To align with the runway

Explanation : Just prior to touchdown a ‘kick off drift’ maneuver is initiated through the rudder control so that the aircraft is rotated about the yaw axis to align it with the runway. This ensures the undercarriage wheels are parallel to the runway center line so that no sideways velocity is experienced by the wheels when they make contact with the runway.

A)
To reduce airspeed and rate of descent
B)
To conserve fuel
C)
To align with the runway
D)
To stabilize the aircraft during crosswinds

Correct Answer :   To reduce airspeed and rate of descent

Explanation : The flare maneuver is the increase in pitch of the aircraft seconds before touching the ground. This is done to reduce the airspeed and the rate of descent. If the flare is not executed correctly it may result in a runway overrun, landing gear collapse or a tail strike.

A)
Automatic control of engine thrust
B)
Flight guidance and control of flight path
C)
Monitor and regulate speed of the aircraft
D)
Automatically switch between different types of communication

Correct Answer :   Automatically switch between different types of communication

Explanation : The tasks of the FMS include Flight guidance and lateral and vertical control of the aircraft flight path, Monitoring the aircraft flight envelope and computing the optimum speed for each phase of the flight and ensuring safe margins are maintained with respect to the minimum and maximum speeds over the flight envelope, Automatic control of the engine thrust to control the aircraft speed. However, the communication systems are taken care manually by the pilot.

A)
1
B)
2
C)
5
D)
7

Explanation : There are two independent FMS in a typical commercial aircraft’s cockpit. FMS-1 is on the Captain’s side and FMS-2 on the First Officer’s side to carry ou the flight management functions. The reason why both are independent is that when one fails the other can take over.

A)
Control stick
B)
Control levers
C)
Control Switches
D)
Keyboard and Cursor Control Unit

Correct Answer :   Keyboard and Cursor Control Unit

Explanation : The flight crew can navigate through the pages of FMS and can consult, enter or modify the data via the Keyboard and Cursor Control Unit (KCCU). The Keyboard and Cursor Control Unit (KCCU) enables the flight crew to navigate through the FMS pages on the MFD and enter and modify data on the MFD and can also perform some flight plan revisions on the lateral Navigation Display (ND).

A)
Primary Flight Display
B)
Multi Function Display
C)
Keyboard and Cursor Control Unit
D)
Target Detection and Locking System

Correct Answer :   Target Detection and Locking System

Explanation : The cockpit interfaces to the flight crew provided by each FMS comprise a Navigation Display (ND), a Primary Flight Display (PFD), a Multi-Function Display(MFD), a Keyboard and Cursor Control Unit (KCCU) and an Electronic Flight Instrument System (EFIS) Control Panel (EFIS CP).

A)
Control over flight plan
B)
C)
Control over graphical and textual FMS data
D)
Control over flight performance

Correct Answer :   Control over graphical and textual FMS data

Explanation : The EFIS Control Panel (EFIS CP) provides the means for the flight crew to control the graphical and textual FMS data that appear on the ND and PFD. Control over flight plan and performance is given by MFD. Navigation through the pages is by KCCU.

A)
4
B)
3
C)
2
D)
1

Explanation : There are a total of three Flight Management Computers FMC -A, FMC -B, FMC -C. They are necessary to carry out the necessary functional computations. They can be reconfigured to maintain the system operation in the event of failures.

A)
Single mode
B)
Double mode
C)
Loss of one FMC
D)
Independent mode

Explanation : In Single mode operating mode of the FMS two of the FMC is not in operation and this might cause one of the two FMS to fail. Hence both the FMS get information from one FMC.

A)
GPS filter
B)
Kalman filter
C)
Position error filter
D)
Gyro and accelerometer filter

Explanation : The FMS combines the data from the navigational sources, comprising the inertial systems, GPS and the radio navigation systems, in a Kalman filter to derive the best estimate of the aircraft position. Each navigation system has its own advantages and limits, a Kalman filter combines the resource from all the systems to provide a more accurate position of the aircraft.

38 .
What is the output for the following system?
A)
Aircraft position
B)
All the fight data
C)
Gyro and accelerometer values
D)

Explaination : The final output of a Kalman filter is the best estimated aircraft position derived from various radio and inertial/GPS sensors. The direct information from the sensors ( raw data) cannot be used directly for accurate position location as their error increases with time.

A)
Inertial (IRS) – GPS
B)
Inertial (IRS) – VOR/DME
C)
Inertial (IRS) – DME/DME
D)
GPS only

Explanation : Each FMS computes the aircraft position and the position accuracy. The FMS computed position is an optimum combination of the inertial position and the GPS or radio position, depending on which equipment provides the most accurate data. This results in four navigation modes: Inertial (IRS) – GPS, Inertial (IRS) – DME/DME, Inertial (IRS) – VOR/DME, Inertial (IRS) only. The only GPS is not used as the position information is within a radius where the aircraft is flying.

A)
CG position
B)
Aircraft weight
C)
Position of the aircraft
D)
Wind and temperature models

Correct Answer :   Position of the aircraft

Explanation : The FMS continually monitors the aircraft envelope and ensures that the speed envelope restrictions are not breached. It also computes the optimum speeds for the various phases of the flight profile. This is carried out taking into account factors such as: Aircraft weight – computed from a knowledge of the take-off weight and the fuel consumed (measured by the engine flow meters), CG position – computed from known aircraft loading and fuel consumed, Flight level and flight plan constraints, Wind and temperature models, Company route cost index.

A)
1 hour
B)
24 hours
C)
28 days
D)
1 month