Avionics Mcqs - Set 1

ANSWER: View and assimilate the flight data with his head up in a transparent display

Explanation:
A major improvement in the man-machine interface is the HUD system. The major advantage in HUD is that the pilot is able to view and assimilate the important flight data parameters whilst head up and maintaining full visual concentration to the outside world. The area at which the flight parameters are displayed is only on the transparent display panel thus the pilot does not have a 360° display.

ANSWER: Throttle position

Explanation:
A typical head up display system in a commercial aircraft consists of airspeed, altimeter, heading, slip/skid indicator, turn/bank indicator, artificial horizon lining, angle of attack indicator, vertical speed indicator, flight path vector and much more depending upon the customer requirements.

ANSWER: Information displayed is focused at infinity

Explanation:
A collimated display is a display in which the rays of light emitted/reflected is parallel to the display. Since the rays of light are parallel, its focus is at infinity, thus the pilot is able to view the information on the HUD without changing his focus from the outside world scene without parallax error. Also, the ray of light from a collimated display would not disperse with distance.

ANSWER: Radar and FLIR (Forward Looking InfraRed)

Explanation:
No explanation is available for this question!

ANSWER: CRT -> mirror -> collimating lens -> combiner glass -> pilot

Explanation:
The symbols and flight parameters are generated and magnified by the CRT (Cathode Ray Tube) and is reflected almost 90° by a mirror. The reflected rays are passed through a collimating lens which produces a parallel ray of light with focus at infinity. The collimated rays are then displayed in a combiner glass which combines the outside world picture with the flight parameters generated to be viewed by the pilot.

ANSWER: True

Explanation:
The instantaneous FOV is the total angular coverage of the outside world scene which can be viewed by the pilot at any particular instant.
IFOV=2tan-1 D/2L, where a D= diameter of collimating lens and L=length of pilot’s eyes to the collimating lens. Clearly, as the position of view changes, L changes resulting in a change in IFOV.

ANSWER: 12.6°

Explanation:
D=100mm, L=50+400 =450mm (Since L is the distance from the observer to the collimating lens)
IFOV = 2 x tan-1 (D/2L) =2 x tan-1( 100/2×450) = 12.6803° ≈ 12.6°

ANSWER: Computing flight parameters

Explanation:
The flight parameters are computed by the air data computer. The various controls and functions carried out by the HUD processor are display formats, axis conversion, parameter conversion, format management, brightness and contrast control, power supply and calibration.

ANSWER: 7:3

Explanation:
A combiner allows 70% of the outside world light and 30% of the CRT produced collimated light to pass through it. Thus contrast ration= brightness of real-world light : brightness of CRT light = 70 : 30 = 7 : 3 .

ANSWER: To meet the required brightness level

Explanation:
To clearly see the flight parameters displayed on the combiner glass against the bright sky, it is necessary to achieve a display brightness of 30,000 Cd/m2. This high brightness requirement is the reason why CRT is used instead of LCD or LED, even though CRT’s are heavier and require more power to run.

ANSWER: Altimeter, airspeed indicator, artificial horizon and heading indicator

Explanation:
Avionics update is one of the effective ways to extend the life of an aircraft. The technology is undergoing an exponential growth and is hence viable to use multifunctional CRT displays in places of mechanical dials. However, the basic T instruments, the altimeter, airspeed indicator, artificial horizon and heading indicator are retained because of their importance in flight control. In modern cockpits, even these are being replaced by solid-state devices with LCD display.

ANSWER: Do not require any illuminating source

Explanation:
OLED displays have numerous advantages over the LED display in the aviation industry. They have a high resolution and are super thin flat panel which can even be curved. It is an emissive display and thus do not require any backlighting. This obviously reduces weight and is optimal for the aviation industry.

ANSWER: Altimeter, vertical speed indicator, artificial horizon, heading/compass indicator and Mach meter

Explanation:
The instruments that are replaced by the PFD are the basic instruments necessary to fly an aircraft. These instruments are altimeter, vertical speed indicator, artificial horizon, heading/compass indicator and Mach meter. All the primary information is shown in the PFD so that the pilot does not have to scan for information.

ANSWER: Probability of failure

Explanation:
Although high tech LED Displays are available the mechanical systems are still used as a fail-safe for the LED display. There is always a chance of electrical failure due to engine failure and power supply may be cut off. In situations like this mechanical systems are necessary to land the plane safely.

ANSWER: Take more space in cockpits

Explanation:
In a typical fighter aircraft there are hundreds of flight parameters and focus cannot be given to all of them. In a dial gauge cockpit, the pilot has to keep track of all the parameters by looking into various gauges which are quite confusing and arises a lot of man-made error. To overcome this problem LED/LCD displays are used which are bigger in size for the same weight and customizable. They also take up a lesser place in the cockpit as they are super thin and flat.

ANSWER: Take more space in cockpits

Explanation:
In a typical fighter aircraft there are hundreds of flight parameters and focus cannot be given to all of them. In a dial gauge cockpit, the pilot has to keep track of all the parameters by looking into various gauges which are quite confusing and arises a lot of man-made error. To overcome this problem LED/LCD displays are used which are bigger in size for the same weight and customizable. They also take up a lesser place in the cockpit as they are super thin and flat.

ANSWER: 2

Explanation:
A typical civil aircraft cockpit will have 4 displays, 2 Primary Flight Displays, and 2 Multi-Functional Displays. The 2 PFDs are duplicated (i.e; they display the exact same information) one for the pilot and one for the co-pilot. The other two displays can be chosen what to show either by the pilot or the copilot.

ANSWER: Accurate measurements

Explanation:
Although electromechanical instruments have been used for a long period of time, the cost of ownership of such instrument is high. These also depend on very low friction precision mechanisms which require skilled labor for repair. Since they have rotating components in them they have inevitable wear and deterioration in the spin axis bearing system. Due to this, their measurements may not be accurate with time.

ANSWER: Altimeter, airspeed indicator, artificial horizon

Explanation:
The standby attitude indicator, standby altimeter, and standby airspeed indicator are replaced with a single solid-state integrated standby instrument system packaged in a 3 ATI case. They consist of solid-state gyros and accelerometers, solid-state pressure sensors along with a microprocessor and color AMLCD.

ANSWER: 28V DC

Explanation:
The Solid-state integrated standby instrument operates from the 28V DC supply produced by the emergency batteries. The integral power conditioning electronics are designed to cope with the variations in the battery supply voltage.

ANSWER: True

Explanation:
The instruments are of higher accuracy because of the use of solid-state sensors and the ability to apply complex corrections using the embedded microprocessor. Electro-mechanical instruments are limited in the complexity of the corrections which can be made.

ANSWER: Using HMD the pilot has a FOV (Field OF Vision) of 360° without moving his head

Explanation:
The FOV of an HMD is 360° in the sense that the pilot can look around(by moving his head) in all direction and still view the flight parameters in his line of sight. If the pilot does not move his head the FOV the HMD provides ranges from35° to 50° depending upon the type of aircraft and its role.

ANSWER: Geometry of the cockpit

Explanation:
The geometry of the cockpit does not affect the HMD nor the helmet as the helmet is worn by the pilot and the FOV of the HMD moves with the pilot’s head. Some of the factors that are essential are the minimum weight for comfort while wearing the helmet for long flight hours and in high g maneuvers, crashworthiness of the helmet with HMD and communication systems integrated no interference with other objects in the cockpit such as oxygen mask as it is crucial at ejection at high speeds.

ANSWER: 7.2kg

Explanation:
800grams = 0.8 kg, during a 9g turn the pilot will experience a gravitational force 9 times that of a normal person at Earth surface. The total weight felt by the pilot = 0.8 x 9 = 7.2kg. Typical HMD helmets weigh around 1kg and at 9g the weight felt by the pilot will be 9kg which is just acceptable.

ANSWER: Keeping the head in the upright position

Explanation:
Keeping the head always in an upright position is not an option for pilots since the pilot will lose situational awareness if he does so. The pilot will feel the inertial forces irrespective of his head position. By reducing the moment of inertia we can reduce the inertial torques experienced. Reducing weight and positioning the CG of the helmet with the pivoting point of head ensures that there are minimal out of balance moments.

ANSWER: Provide target locking capabilities by looking at the target

Explanation:
A Helmet Mounted Sights in combination with a head tracker system provides effective means for the pilot to lock on to target. The pilot can look at the enemy aircraft and lock on to it. The relative position of the enemy is then calculated by the head position of the pilot and sent to missiles to engage the target. A typical seeker head needs to be pointed to within about 2° of the target to achieve an automatic lock on.

ANSWER: one eye with display and the other eye without display

Explanation:
Monocular rivalry occurs because the brain is trying to process different images from each eye and rivalry can occur between the eye with a display and the eye without a display. The effect is most significant when flying at night when one eye sees less light whereas the other eye sees more. To overcome this binocular system is used where both the eyes are presented with the flight parameters.

ANSWER: Provide night vision capabilities

Explanation:
IIT is an image intensification device which complements the infrared viewing system by providing night vision. The image form the Image Intensifier Tube is a phosphor screen which emits green light in the centre of the visual band where the eye is most sensitive.

ANSWER: Virtual reality display

Explanation:
Virtual reality displays are for future virtual cockpits where the image is directly projected onto the retina of the pilot by a raster scanned laser light beam. The current technology of implementing a virtual retinal display involves lasers, optical fibers and miniature vibrating mirrors for raster scanning the retina of the eye, together with coupling optics.

ANSWER: Situational awareness is needed in civil aircraft

Explanation:
For a civil aircraft the situational awareness is not essential as they are inherently safer and do not execute high g maneuvers. Also, situational awareness is an important factor only when the flight parameters are rapidly changing, for a civil aircraft which is in steady level flight for most of its flight time situational awareness is not necessary.

ANSWER: True

Explanation:
Dealing with guided weapons system such as missiles and laser-guided bombs the accuracy of HMD is adequate enough but for unguided weapons such as guns, unguided bombs, and rockets the accuracy is not yet feasible since the HMD is constantly moving with the pilots head. Currently, the boresight angles for HMD are 8 to 10 mRad, whereas for HUD it is 1.5 to 2 mRad.

ANSWER: Matrix array of infrared beams

Explanation:
A typical tactical control panel uses a matrix of infrared beams across the surface of the display containing various functional keys. Touching a specific function key on the display surface interrupts the x and y infrared beams which intersect over the displayed key function and hence signal the operation of that particular key function.

ANSWER: Direct voice input

Explanation:
DVI control is direct voice input control through which the pilot can enter flight and navigational commands through voice.

ANSWER: Speech recognition system

Explanation:
The commands given by the pilot is recognized by a speech recognition system which compares the spoken audio with preloaded vocabulary templates. If the command is recognized indication is given either aurally or visually to confirm the command.

ANSWER: reduce pilot work load

Explanation:
DVI control system is used to control the aircraft using voice commands, thus the pilot need not have to operate push buttons, switches. This reduces the workload on the pilot during heavy workload operations such as combat.

ANSWER: Systems that require a pause between each word to recognize

Explanation:
No explanation is available for this question!

ANSWER: False

Explanation:
The DVI control system must be super sensitive to the voice of the pilot so that it can be operated in cockpit noise environment. In a fast jet combat aircraft, the background noise levels can be very high.

ANSWER: Warning messages to pilot

Explanation:
Speech synthesizers are used to provide voiced warning messages to the pilot of system malfunctions and failures. They also aid DVI systems to provide feedback that a spoken command has been correctly recognized.

ANSWER: voice, throttle, stick control

Explanation:
When the audio/tactile system, FBW, and the automated engine control is combined it is called the Voice, Throttle, Stick control. It is used in fighter aircraft such as Eurofighter Typhoon to reduce pilot workload.

ANSWER: Improve accuracy for targeting

Explanation:
Using an eye tracker the pilot’s gaze can be measured with accuracy which helps in better targeting. A fast and accurate data system can be achieved by this means without any discomfort to the pilot. They can track the eye by exploiting the principle of corneal reflection.