Avionics and Instruments Flashcards
(212 cards)
1
Q
What are the three types of aircraft instruments?
A
Primary Flight Instruments
Engine Instruments
Navigation Instruments
2
Q
What types of instruments are Direct Sensing Instruments?
A
Analogue Instruments are often Direct Sensing
3
Q
What types of instruments are Remote Sensing?
A
Digital Instruments
4
Q
What are the main advantages of Digital instruments over Analogue?
A
Reliability
Accuracy
Flexibility
Cost
5
Q
What are the Primary Flight Instruments
A
Attitude Indicator (AI)
Airspeed Indicator (ASI)
Altimeter (ALT)
Vertical Speed Indicator (VSI)
Horizontal Situation Indicator (HSI)
Turn and Slip Indicator (T&S)
6
Q
How many primary flight instruments are there?
A
6
7
Q
What is the classic ‘tee’ shape of primary instruments?
A
ASI, AI, ALT, HSI
8
Q
What is a PFD?
A
Primary Flying Display
9
Q
Power Lever or Thrust Lever?
A
Power Levers for Propellers
Thrust Lever for Jet Engine
10
Q
What is Power?
A
The rate of doing work
Distance/Time
11
Q
What is Torque?
A
The rotating force in the gearbox to turn the propeller.
12
Q
What are the Control Instruments?
A
Power Instruments
Attitude Indicator
13
Q
What are the Performance Instruments
A
ASI
ALT
VSI
HSI
T&S
14
Q
What is the equation for performance?
A
Power + Attitude = Performance
15
Q
What is Static Pressure?
A
Static presure is the ambient pressure
16
Q
What is the AHRS?
A
Attitude Heading Reference System
17
Q
What is the Indirect reading of the ASI
A
Pitch information
18
Q
What is the indirect reading of the ALT?
A
Pitch
19
Q
What is the indirect reading the HSI
A
Bank or Yaw
20
Q
What is the indirect reading of the Turn Indicator
A
Bank or Yaw
21
Q
What is the indirect reading of the Slip Indicator
A
Yaw
22
Q
What is an ESI?
A
Electronic Standby Instrument
23
Q
Where is the Tropopause at its coldest?
A
The Equator, due to its highest point 56 000 ft
24
Q
What is Pressure Altitude?
A
The altitude indicated when the altimeter is set to 1013.25 hPa.
Standard Pressure Setting.
25
What is the Density Altitude?
DA is the pressure altitude adjusted to take into consideration the actual temperature of the air.
DA = Pressure Altitude + 120t (where t is the ISA temperature deviation)
26
What is another term for Static Pressure?
Ambient Pressure
27
From where is static pressure provided?
Static Vents
28
What is Alt Statik?
A backup system should the Static Port freeze of become blocked.
29
How does the Pitot Tube work?
Air in motion possesses energy and therefore exerts a pressure on any object in its path (the pitot tube and chamber)
As Airspeed increases the pressure air entering the pitot tube (ram air) increases.
30
What happens to Static Pressure as we climb?
It reduces.
31
What is the capsule within the Altimeter known as?
Aneroid Capsule.
32
What types of Altimeter are there?
Simple
Sensitive (multiple aneroid capsules)
Servo-assisted altimeter
Digital Display
Cabin Altimeter
33
What is PITHBLOT?
Errors of the Altimeters.
34
What is the **P** in PITHBLOT?
**Pressure Error (Position Error) -** Accuracy of static vents not reading pure static pressure.
35
What is the **I** in PITHBLOT?
**Instrument Error** - caused by irregularities during manufacture, residual error will be noted on a correction card.
36
What is the **T** in PITHBLOT?
**Temperature Error** - Arises when the atmospheric conditions differ from those assumed by standard atmosphere used to calibrate the altimeter.
37
What is the **H** in PITHBLOT?
**Hysteresis Loss** - Imperfect elastic response. Difficult to predict, most noticable in sharp climbs or descents.
38
What is the **B** in PITHBLOT
**Blockages and Leaks** - Uncommon occurences, can be caused by frozen pipework, insects, other obstructions.
39
What is the **L** in PITHBLOT?
**Lag Error** - Caused whenever height is changed rapidly, varies with the rate of change. Reduced by the fitting of a vibration system.
40
What is the **O** in PITHBLOT?
**Orthographic Effect** - Caused when a current of air meets a barrier of hills or mountains.
41
What is the **T** in PITHBLOT?
**Transonic Jump** - At high speeds, near Mach 1, if a shock wave passes over the static source, a rapid change in static pressure will occur. This gives an error in the altimeter indication for the duration of the disturbance.
42
What types of ASI are there?
Simple ASI
Sensitive ASI
Servo ASI
43
What is Dynamic Pressure?
Dynamic Pressure is the difference between Static pressure and Pitot Pressure
44
How is the Flap Operating Range described on the ASI?
A white arc.
The range within the arc represents normal speeds for take off or landing with flaps extended.
45
What types of ASI errors are there?
Instrument Error
Pressure Error
Compressibility Error
Density Error
46
What is CAS?
Calibrated Air Speed (CAS)
47
What is EAS?
EAS is Equivalent Air Speed
It is CAS corrected for compressibility error.
48
What is TAS?
True Air Speed (TAS)
49
What is **Mach**?
**Mach** is the ratio of true air speed to the local speed of sound.
50
What is the structure of a Machmeter?
A Machmeter is an aircraft pitot-static system flight instrument that shows the ratio of the true airspeed to the speed of sound.
An airspeed indicator with a linked altimeter aneroid capsule.
51
What are the components of a VSI?
A differential capsule contained within a case. With a calibrated leak.
52
How does an Instantaneous VSI work?
There are small weights that act as accelorometers to remove lag from the pressure changes.
53
What is the purpose of an Instantaneous VSI?
A IVSI removes the initial lag error when a climb or descent is started. They utilise accelerometers or accelerating weights.
54
What is an ADS?
Air Data System
55
What components comprise a basic ADS?
Probes and Sensors for pressure, temperature, angle of attack and side slip.
Transducers to convert sensor air data into electronic signal.
Air Data computers (ADC) to process the air data for aircraft systems and displays.
56
What is the role of a **Transducer** in an ADS?
The transducer converts sensor air data into electronic signals.
57
What are the roles of **Probes and Sensors** in an ADS?
The probes and sensors check pressure, temperature, angle of attack and sideslip.
58
What is the role of the **Air Data Computer**?
The ADC processes the data input from the sensors, aplies any necessary corrections and supplies output data in a digital form which can be converted into graphical presentations on the primary flight displays.
59
What are the advantages of the Air Data System?
The bulk and complexity of pitot/static pressure pipework is removed.
One ADC replaces the multiple analogue pressure instruments.
Eliminates analogue instrument error.
Increased accuracy and sensitivity.
Minimal time lag.
Digitised air data enables flexibility in presentation.
60
How can we get vertical position from air pressure?
Pressure varies with increases in height
61
What are the 6 degrees of freedom?
Six degrees of freedom (6DoF) refers to the freedomof movement of a rigid body in three-dimensional space. Specifically, the body is free to move forward/backward, up/down, left/right (translation in three perpendicular axes) combined with rotation about three perpendicular axes, often termed pitch, yaw, and rol
62
What are the three types of gyroscopes?
Spinning
Optical
Vibrating
63
What is **Inertia**?
The resistance of an object to any change in its state of motion.
64
What is **momentum**?
The product of an object's mass and velocity.
65
What is **angular velocity**?
An objects speed of rotation or spin.
66
What is **Moment of inertia**?
The product of the moment arm about the spin axis that an object's mass is said to act and the total mass of the object.
67
What is **angular momentum**?
The product of angular velocity and the moment of inertia which defines the amount of force needed to oppose rotation.
68
What is the **conservation of angular momentum**?
As angular momentum is the product of the moment of inertia and angular velocity, if one is decreased so the other will increase to conserve a spinning objects angular momentum.
69
What is the **First Law of Gyrodynamics**?
If a rotating body is free to move in any axis through its centre of mass then its spin axis will remain fixed in intertial space.
**Rigidity**
70
What is the **Second Law of Gyrodynamics**?
If a constant torque is applied about an axis perpendicular to an unconstrained, symmetrical object's spin axis, then the spin axid will precess steadily about an axis mutually perpendicular to both the spin axis and torque axis.
**Precession**
71
What property do Displacement Gyroscopes utilise?
Gyroscopic Rigidity.
72
What is a **rate gyroscope**?
A rate gyroscope system is constrained with a single degree of freedom.
When the gyro experiences a rotation about the constrained axis, it will precess about an axis mutually perpendicular to the applied torque and its spin axis.
73
What are the classifications of spinning gyroscopes?
Rate Gyroscope
Rate-integrating Gyroscope
Displacement Gyroscope
74
What are the applications of **displacement gyros**?
Vertical - **Attitude Indicator**
Horizontal - **Direction Indicator**
75
What are the practical applications of a **rate gyro**?
Rate of Turn
76
What are the practical applications of the **rate-integrating gyros**?
Inertial Measurement units.
77
What is the definition of **wander**?
Wander is defined as any movement of the spin axis away from the reference frame in which it is set.
78
What are the causes of wander?
Real wander- caused by imperfections in the gyroscope mechanism.
Apparent wander- The rotation of the Earth or transportation of the gyroscope from one point on Earth to another can give an indication of apparent wander with regards to the Earth's surface, even though the gyroscope's actual orientation remains fixed in inertial space.
79
Into what components can wander be resolved into?
**Drift and Topple**
80
What is **Drift** when referring to gyros?
**Drift** is the wander of the spin axis in the horizontal plane.
81
What is **Topple** when referring to Gyros?
**Topple** is wander of the spin axis in the vertical plane.
82
What is the **sagnac effect**?
beam of light is split and the two beams are made to follow the same path but in opposite directions. On return to the point of entry the two light beams are allowed to exit the ring and undergo interference. The relative phases of the two exiting beams, and thus the position of the interference fringes, are shifted according to the angular velocity of the apparatus. In other words, when the interferometer is at rest with respect to a nonrotating frame, the light takes the same amount of time to traverse the ring in either direction. However, when the interferometer system is spun, one beam of light has a longer path to travel than the other in order to complete one circuit of the mechanical frame, and so takes longer, resulting in a phase difference between the two beams. This arrangement is also called a Sagnac interferometer. Georges Sagnac set up this experiment to prove the existence of the aether that Einstein's theory of special relativity had discarded.
83
What are the benefits of a **ring laser gyro?**
An RLG is a gyro that is more sensitive and accurate.
There are no moving parts, no wander errors, no spin up time.
Resistant to shock, vibration and temperature changes.
They are small, durable and reliable.
84
What is a **FOG**?
Fibre Optic Gyro
85
What are the benefits of FOGs?
Fibre Optic Gyros
They use optical fibre, to enhance the Sagnac effect. Laser light is sent down km of optical fibres in concentric coils, enclosed in a small container. Increasing sensitivity to angular motion.
86
What are the advantages of **FOGs**?
Fibre optic gyros
Have high sensitivity.
Are relatively cheap.
87
What effect is utilised by Optical Gyros?
They utilise the **Sagnac effect**.
88
What gyros utilise the **Sagnac effect**?
Optical Gyros
89
What effect does a **vibrating structure gyro** utilise?
Coriolis effect.
90
What is a **MEMS**?
Micro Electric-Mechanical Systems
They can be utilised for...
vehicle stability control
robotics
computer game control
segway
camera stabilisation
smart phone operation
91
What is the principle behind the Vibrating Structure Gyros?
**Coriolis Effect.**
92
What was the order of creation for Vibrating Structure Gyros?
Wine Glass Resonator
Hemispherical Resonator Gyros (HRG)
MEMS
93
What is the scientific theory behind optical gyros?
**Sagnac Effect**
94
What is the scientific theory behind vibration gyros?
Coriolis Effect
95
What are the key components of an elementary form radar?
**Transmitting Antenna**
**Receiving Antenna**
**Energy Detecting Device/Receiver**
96
What is a **pulse radar**?
**Pulse Radar**
Transmission is concentrated into very short pulses.
Separated by sufficiently long intervals.
Echo determines the target range.
97
What is **target echoing area**?
Normal targets are complex in shape and do not re-readiate isotropically.
The echoing area of the aircraft targets may vary with aspect over very wide limits.
98
What is **clutter** on the radar?
Unwanted radar echo, includes refelctions from:
land, sea, rain, birds, chaff
99
What is **pulse width**?
**Pulse Width**
Time duration of a single pulse (represented by tau)
100
What is **pulse length**?
**Pulse Length**
Distance between the leading and trailing edge of a pulse.
101
What is **PRI**?
**Pulse Repetition Interval (PRI)**
The time period between the start of one pulse and the start of the next pulse.
102
What is **PRF**?
**Pulse Repetition Frequency (PRF)**
The number of pulses occuring in one second.
103
What are the effects of increased Radar frequency on Resolution?
As frequency increases resolution and precision increases.
104
What are the effects of increased Radar frequency on Interference?
As frequency increases interference increases.
105
What are the effects of increased Radar frequency on Power and Operating Range?
As frequency increases power and operating range reduce.
106
How is range information transmitted by the Radar return?
Range information is provided through timing marks in the transmitted carrier - by modulating amplitude or frequency.
107
What are the fundamental division of radar types?
**Pulse systems** - for range
**Continuous wave** - for velocity
**Other (ie Pulse Doppler)**
108
What are the effects of the atmosphere on Radar?
Pressure has no impact.
Increase in moisture increases refraction.
Decrease in temperature increases refraction.
109
What is a **Moving Target Indicator**?
A **Moving Target Indicator (MTI)**
employs a pulse transmission and discriminates between fixed and moving targets. MTI recognises the presence or absence of phase shift in the echo signals.
110
What is a **continuous wave radar**?
A **CWR** sends the transmitted and received signals continuously.
111
What is a **Frequency Modulated Continuous Wave Radar**?
A **FMCW radar** has the ability to measure the range of a discrete targets, but it cannot resolve a number of targets at differing range.
112
Do long range radars have high or low PRFs?
Typically low, as their role is early warning and detection.
A low PRF allows unambiguous determination of range over longer distances.
113
What are the three main applications of Radar?
**Search**
**Tracking**
**Fire-Control**
114
What are the roles of a **Search Radar**?
**Search Radar**
Scan a wide area less frequently. They transmit short pulses over a wide area and only distinguish between targets that are far apart.
115
What is a **Tracking Radar**?
**Tracking Radar**
Scan a narrow area more frequently. They continuously emit EM waves and detect the target when it comes in the path of the waves. Tracking radars scan a much narrower area far more frequently than search radars. Before they can track they must first acquire the target.
116
What is a **fire-control radar**?
A **FCR** specifically directs weapons onto a target. An FCR is a radar that is designed to provide information to a fire-control system in order to calculate a firing solution. It emits a narrow intense beam of radio waves to ensure accurate tracking information to minimise the chance of losing track of the target.
117
What type of Radar will have the highest PRF?
A Fire Control Radar will have a very high PRF and very high antenna rotation.
They have extreme accuracy, very narrow bandwith but limited range.
118
What are the rhymes for adjusting bearing for magnetic variation?
If the variation is west, the magnetic heading is best (add).
If the variation is east, the magnetic heading is least (subtract).
119
What is the 1/60 Rule?
A 1 degree error of track will lead to a deviation of 6000ft/2000yds/1nm over a distance of 60nm.
120
What is **Horizontally** when referring to compasses?
**Horizontality**
The ability of the compass to use the magnetic field as a directive force at higher latitudes. Horizontality is caused by dip angle.
To keep the compass as horizontal as possible it is mounted on a pendulous pivot. The pivot point is no longer coincident with the CoG of the compass.
121
What arrangement helps overcome horizontality of compasses?
A pendulous suspension of the compass, not attached to the compass assembly itself helps overcome horiontality
122
What is **aperiodicity** or **deadbeat** for compasses?
**Aperiodicity** is a compasses ability to resist disturbance caused by manouevre, acceleration and turbulence.
It is the ability of the compass to settle down to reduce oscilliations and instability around magnetic north.
123
How can **aperiodicity** be assisted for a compass?
Use mulitiple short magents
Encase the assembly in a fluid filled bowl.
Aperiodicity is the ability of the compass to resist oscillations caused by oscillations around magnetic north.
124
What is Operational Accuracy of a Direct Indicating Compass System?
Op Accuracy is ± 10 degrees
125
What is the Target Accuracy of the Direct Indicating Compass?
Target Accuracy is ±2.5 degrees
126
What are the advantages of the DICS compass?
Cheap to install and maintain
Small and light
Simple to use
Requires no power supply.
127
What are the limitations of the DICS compass?
Significant turning error
Unusable near the poles
Subject to EM interference
Gives mag heading only
Cannot provide a heading feed.
128
How does acceleration affect the operation of a Direct Indicating Compass?
DICS experience error during horizontally acceleration/deceleration. The CoG of the magnetic assembly moves away from its normal S&L flight positiosn to belwo the pivot, thereby causing a rotation of the assembly and an error in the compass reading. Errors do not occur in N/S direction or at the equator.
On East/West headings, acceleration/deceleration causing an error.
129
On a North/South heading what causes compass error?
North/South, turns cause compass error not acceleration/deceleration
130
During turns how is the operation of the Gyro compass adjusted?
During turns the Flux Valve (Detector unit) outlet is disconnected.
During the turn, you have to rely on the short-term accuracy of the gyro as the heading reference.
131
When should a compass swing be carried out?
When compass is replaced
If accuracy is in doubt
After a major service
Following lightning strike
Ferromagnetic loads
Been stored on same heading for long time.
Subject to shock
132
What are the key features a DICS compass must have?
Horizontality
Sensitivity
Periodicity
133
What type of Errors can be present for a compass?
East/West (Accleration)
North/South (Turn errors)
134
What compass features can assist aperiodicity?
Fluid filled bowl and less friction assist aperiodicity.
135
What is the accuracy of the DICS compass?
Operational Accuracy ±10°
Target ±2.5°
136
What type of aerial does an ADF have?
Loop and Sense
137
What is a cardioid?
The cardioid polar diagram is the resultant of the loop aerial and sense aerial to remove postional ambiguity in the sytem.
138
What is **night effect**?
NDB/ADF systems use vertically polarised waves. The ADF uses the surface way for direction finding.
By day the D region of the Ionosphere absorbs signals in the LF/MF bands.
At night, skywave interaction with the surface wave causes phase interference, this induces field errors in loop aerial.
139
What types of errors are there on beacon transmissions?
Night Effect
Synchronous transmission
Bank Error
Coastal Refraction
Quandrantal Error
140
What is ADF?
Automatic Direction Finding
Using low and medium frequencies.
Surface wave.
2 aerials, loop and sense to form cardioid.
141
What is a VOR?
VHF Omnidirectional Range
142
What is the symbol for a VOR?
143
What two types of signal are used for a VOR Ground Beacon?
Omni directional reference signal (30Hz FM)
Rotating Direction Signal (1800RPM, 30Hz AM)
144
What is a VOR Ground Beacon measuring?
Phase difference to identify bearing.
Signal fires at magnetic north, then again from return from aircraft VOR. The phase difference (time) identifies the bearing.
145
What frequencies does VOR utilise?
VOR uses bandwith above those used for FM broadcasts.
112. 000 - 117.95 MHz reserved for VOR
108. 000 - 111.85 MHz range shared between VOR/ILS
* (Even tenths are VOR, 108.20 MHz 108.25 MHz, Odd tenths are ILS, 108.30 MHz 108.35 MHz)*
146
What is the symbol for a VOR/DME
147
What are the basic principles for operation of a DME?
An aircraft (interrogator) transmits a stream of 25 omni-directional pulse pairs on the interrogator carrier frequency of the ground station.
The ground station retransmits the pulse pairs after a 50microsec delay on a carrier frequency -63MHz less than the Interrogation freq.
The aircraft identifies its own unique pulse pair stream and calculates the range (ping pong/2)
148
What is DME saturation?
DME ground beacon can only handle 100 targets max
149
Who uses TACAN?
TACAN is the military VOR/DME
150
What is the symbol for a TACAN
151
What is a VORTAC?
A VOR/TACAN unit for civilian and military operations.
152
Why is a TACAN more accurate than a VOR/DME
The TACAN is 'looking' in a 40 degree arc rather than 360.
153
What channels are present for a TACAN?
X
Y (often used for air-air)
154
What are the accuracy improvements of TACAN over VOR/DME?
3 x more accurate
± 0.5 degrees
155
What frequency band does TACAN operate?
UHF
962 - 1213 MHz
252 channels, 1 to 126, X and Y.
Transmits on a given frequency and receives a return ±63 MHz.
156
How many TACAN channels are there?
256
Channels 1 - 126, X and Y
157
What are the key components of a typical EFIS (Electronic Flight Information System)?
Air Data System (ADS)
Air Data Computer (ADC)
Attitude and Heading Reference System (AHRS)
Engine Indicating and Crew Alerting System (EICAS)
Integrated Avionics Unit
Data Bus
Primary Flight Displays (PFD)
MFDs
Integrated Electronic Standby Instrument (IESI)
158
What is an AHRS?
Attitude and Heading Reference System
159
What is N1/N2 on the Phenom EICAS display?
160
What are the three main components of a Data Bus?
Bus Controller (e.g. PFD) - controls flow of data
Bus Monitor/Recorder - Cockpit Voice and Data Recorder
Remote Terminals
161
What is Mil Std 1773?
A high speed data bus network using fibre-optic cable, supporting data rate up to 100Mb/s
1773 has a higher data rate via fibre optic cable than 1553 which is copper cable.
162
What are the basic information feeds for the Air Data Computer?
Pitot
Static
Air Temperature
Alpha
163
How is the course deviation scale and bar displayed on the HSI?
**Course Deviation Scale (dots)**
Each dot represents a distance from the setting. Measure deviation from selected course.
**Course Deviation Bar**
Shows magnitude of course/ILS deviation.
164
What are the two signals for an Instrument Landing System?
Localiser (LLZ)
Glidepath
165
What is the modulation of the left and right hand lobes for a localiser in an ILS?
Right hand lobe is amplitude modulated at 150Hz
Left hand lobe is amplitude modulated at 90 Hz
166
What is the localiser coverage for ±10° and 10-35° from centreline?
18 nm within ±10° of the centreline
10 nm between 10° - 35° from centreline
167
What is the glideslope range in an ILS?
Signal range is 10 nm at 2000 ft within ±8° of the localiser front course.
168
What are the Decision height and Runway Visual Range for Cat I ILS?
Decision Height: Not below 200 ft
Runway Visual Range (RVR): 550 m
169
What is a 3C(IIIC) ILS Category?
No Decision Height limit with dual autopilot, guidance to and along runway and taxiways.
No external visual references required.
170
What number is associated with Schuler Tuning?
84.4 minutes
If a stable platform is disturbed from Earth Horizontal, it will behave like a pendulum with a period of 84.4 minutes
171
How many GPS satellites are present in the constellation?
**27**
with 24 in use at any one time
172
What frequencies does a GPS satellites utilise?
Link 1 (L1) on 1575.42 MHz
Link 2 (L2) on 1227.6 MHz
173
What is the accuracy of Standard Postioning Service GPS?
8m
174
What is the accuracy of the Precise Positioning Service GPS?
4m
175
What INS errors can occur?
**Gimballed systems**
Abrupt gimbal lock can occur during aerobatics or high speed maneouvres.
**Strapdown Systems**
lack many mechanical components but their advanced electronics require careful alignment and cross referencing.
176
What are the three basic types of flight instruments?
Primary Flight Instruments
Engine Instruments
Navigation Instruments
177
Are Analogue Instruments Direct or Remote Sensing instruments?
Analogue instruments tend to be direct sensing instruments.
The relevant parameter is sensed, measured and displayed in a single unit.
178
What is the purpose of Standby Flight Instruments and are they mandatory?
EU Regs state aircraft 5700kg+ or 9 seats+ must have a standby Att-Ind that provides reliable operation for at least 30 mins and works independently of all other aircraft systems.
179
What is Static Pressure and from where is it supplied in the aircraft?
Static pressure is the ambient pressure and is supplied by static vents, either side of the fuselage.
This enables an average pressure to be obtained.
180
What part of the aircraft supplies dynamic pressure?
Pitot Tube.
(Pitot static tubes have integrated static ports which provide a source of static pressure)
181
What aircraft instruments are supplied with static pressure?
ASI
VSI
Altimeter
182
What are the basic components of a **Pitot Static System**?
Ram Air - the air pressure created by the motion of the aircraft enters the pitot tube.
Pressure chamber - comprises static and dynamic pressure entering the chamber.
Static Port and Chamber - provides an average static pressure from multiple ports.
Drain Hole - for the release of moisture.
183
How can the sensitivity of an altimeter be increased?
The addition of secondary, or tertiary aneroid capsules can increase the sensitivity of altimeters.
184
What instruments are **pressure instruments**?
ASI
Altimeter
VSI
Machmeter
185
Total Pressure = ? + ?
Dynamic + Static = Total
186
What pressure instruments have pitot and static pressure?
ASI
187
How does a Machmeter differ from an ASI
A machmeter is an instrument which provides an indication of the Mach Number, (M), which is the ratio between the aircraft true air speed (TAS) and the local speed of sound (LSS).
188
What is the difference between **indicated, calibrated and equivalent air speed**?
**Indicated airspeed** - without correction
**Calibrated airspeed** - without instrument errors.
**Equivalent air speed** - without compression error.
Indicated Airspeed is the speed shown on the airspeed indicator. Calibrated Airspeed is indicated airspeed corrected for position installation error. Equivalent Airspeed is calibrated airspeed corrected for compressibility. True Airspeed is equivalent airspeed corrected for temperature and pressure altitude.
189
What is the heart of the air data system called?
**ADC**
Air Data Computer
190
What are the three types of gyros?
Spinning
Vibrating
Optical
191
What are the classifications of spinning gyros?
Rate
Rate-integrating
Displacement
192
What is the principle of operation expressed by the first law of gyrodynamics?
Rigidity
193
What is the principle of operation expressed by the second law of gyrodynamics?
Procession
194
What are the two types of optical gyro?
Ring laser gyro
Fibre optic gyro
195
What are MEMS?
**Micro electrical mechanical systems**
Microscopic gyros and accelerometers.
196
What is a **Deviation Card**?
A deviation card lists the amount of deviation from magnetic NORTH that is present in your compass, and how much of it you can eliminate for each major heading. This is established through a compass swing.
197
What are the components of a Gyro-mag compass?
Gyroscope
Detector (Magnetic Unit/flux valve)
Transmission and Display
198
How does variation affect the magnetic heading from true?
Variation West, Mag is Best
Variation East, Mag is Least
199
What is an ADC?
**Air data computer.**
Fed with Static, Pitot, Total Air Temp and Alpha
200
What is **IAU**?
**Integrated Avionics Unit**
GPS, Comms, NAV, TAWS, TCAS
201
What are MilStd 1553/1773 and ARINC 429?
**Data transfer standards.**
1773 is the fastest as it is fibre optic.
202
What is the difference between N1 and N2?
N1 - Fan speed
N2 - High pressure compressor stage
203
5 uses of radio NAVAIDS?
At beginning, end of Airways
Centreline of airways.
Fixing.
Approaches.
Holding.
204
What is NDB/ADF?
LF/MF and surface wave
2 aerials, creating cardioid
205
Explain VOR
VOR is VHF
Utilises phase difference
Two signals- omnidirecitional (FM) and rotational signal (AM)
±1 degree
206
Explain DME
UHF signal
It is a form of secondary radar
The aircraft is the interrogator.
Beacon is the transponder.
25 pulse pairs randomly spaced.
Beacon re-transmits ±63 MHz
Ping Pong/2
207
Explain TACAN
**UHF**
Omnidirectional in the middle
Different size oil drums, inner and outer.
Produces 9 sided star 40 degree spacing, 15 revs per second.
208
What is Protected Range?
A column of air in which their is protected reception up to a specific radius and height.
209
Explain ILS
Localiser, left right element, VHF
90/150 Hz provides centreline.
Glide slope, 2000ft, 10nm
210
What is the main error with INS?
Gimbal lock
211
What must be carried out on a strapdown system in flight?
Must be constantly cross referenced to ensure it is in limits.
212
