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HERC REVISION > NAV SPECIFIC TECH > Flashcards

NAV SPECIFIC TECH Flashcards

FMS, RNP, 1553, GPS

1
Q

What are the independent functions of each SP? (Ie computed individually)

A

FD commands
Nav solution

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2
Q

What does partitioned by time and space mean wrt the SPs?

A

designed to protect flight critical functions

Time-protects computational bandwidth for safety critical functions

Space-protects memory space/registers/dedicated interfaces

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3
Q

What does the Flight Management Function provide?

A

Navigation
Route Planning
LNAV/VNAV guidance
RTAs
Prog page predictions
Perf predictions
MCDUs
Datalink
NAV/COM sensor management
Data comms control and routing

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4
Q

What does EGI stand for?

A

Embedded GPS/ inertials

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5
Q

what does a blended INU/GPS solution provide?

A

Position
Attitude
Rate
Filtered update method
Fully populated Nav state vector

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6
Q

What are the characteristics of the pure INU solution?

A

Full Nav state vector
Long term drift due lack of position updating

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7
Q

What are the characteristics of the pure GPS solution?

A

No attitude information
Short term but high accuracy

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8
Q

What does the “gps not in civil” message mean?

A

GPS receiver has lost satellite reception

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9
Q

What can effect INU alignment time?

A

Latitude
Satellite availability

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10
Q

What does PRAIM display?

A

RAIM availability
RAIM hpl
RAIM alert status

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11
Q

What is the only system that sends data to both SPs not just the master?

A

EGIs due time critical nature

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12
Q

How does the comms system work between each channel/bus A/B?

A

Either A or B will be allocated as primary based on continuous health checks by the bus controller (using parity bit)

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13
Q

How are the buses separated to prevent battle damage?

A

A & B separated by at least one inch
1 & 2 separated down opposite sides of aircraft

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14
Q

What is important to note about 1553 intermittent failures?

A

If some info is still getting through the other bus may not take over
Only if a bus is severed completely will the traffic definitely transfer to the secondary bus

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15
Q

How do the SPs communicate using the 1553?

A
  • If SP 1 is master, SP2 becomes a remote terminal on Bus 2
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16
Q

FMCn FAIL plus FMCn NOGO, and POSSIBLY SINGLE OPERATION; what does this mean?
How to ident between 1553 or SP issue

A
  • You can only identify if it’s a 1553 issue not an SP issue by looking at the Equipment history and seeing stuff like TACAN 2 B2 BA FAIL
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17
Q

Why do you select SYS>PWR CTL>ALL ON after an SP event?

A

When two SP resets occur in quick succession (ie 1st reset isn’t complete) the EGIs will be powered off

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18
Q

How many ground monitoring stations and antennas does GPS have?

A

5 monitoring stations updating satellite Nav messages
3 antennas w uplink capability

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19
Q

Where is the zeroise function in the FMS?

A

Init Ref>zeroise

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20
Q

Where are the CMU pages in the MCDU?

A

ACARS > SYS menu > ATS menu

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21
Q

What is the code for the VHFs?

A

RTA-50D

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22
Q

What is the code for the VUHFs

A

AN/ARC210s

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23
Q

What does CMU stand for?

A

Comms management unit

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24
Q

What is the safety standoff for the civil SATCOM antenna? (2)

A

8.5feet
20feet for longer than 3min/hour

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25
Q

Limitation to AWO altimeter

A

Only checked to +/- 200ft above 7000ft by maintenance, therefore unreliable above 7000ft (except hpa)

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26
Q

What are the primary systems used for navigation

A

2x embedded GPS/INS (EGI)/MMR systems

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27
Q

What does the GPS portion of each GPS/EGI do?
How many satellites can it track?

A

Uses precise time & location data from a satellite constellation to determine a/c position.
Up to 12 satellites at once

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28
Q

How does the INS work

A

The Inertial Navigation system
Starts from a known initial position, and using a highly accurate laser ring gyro & accelerometers to calculate the a/c position over time.

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29
Q

What are the five navigation modes in order of preferred use?

A
  • Blended INU/GPS 1 & 2
  • INU only mode 1 & 2
  • GPS only mode 1 & 2
  • INU/RADIO mode 1 & 2
  • No nav mode (inertials only)
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30
Q

What does EHE stand for

A

estimated horizontal error

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31
Q

INU/GPS nav mode drift rate

A

WITHOUT GPS, at max 0.3nm/hr

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32
Q

INU only nav mode drift rate

A

Max 0.8nm/hr

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33
Q

How many satellites are required for RAIM?
exception?

A
  • 5
  • 4 with BARO-AIDING (where the ADC is used as a 5th source)
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34
Q

INU/RAD drift rate

A

Max 0.8nm/hr

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35
Q

Why do we use SPS not PPS

A

SPS is FAA (civil) approved (standard positioning service)
capable of PPS when keyed with crypto

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36
Q

when can you test the EGIs

A

GROUND ONLY (usually by maint) as while the IBIT is occuring, no nav will occur

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37
Q

Why would you turn the EGI into standby & how

A
  • How: turn off & on again via power control page
  • Why: to provide a method of sending initialisation info to the GPS (position/time/date & year)
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38
Q

When would you need to initialise the GPS?
How would you do it?

A

-When the nav sensor index page 3 shows no satellites at all and/or FOM is 9 for example.
- GPS INIT PAGE> IDENT (A/D ICAO code) > DATE > TIME

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39
Q

EGI in flight alignment - when?
how?
What must the aircraft do?
How long does it take?

A
  • In flight, GPS position is valid & FOM is 4 or less.
  • MCDU: Select IN FLIGHT
  • Straight & level & unaccelerated
  • 10mins
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40
Q

During an in flight EGI alignment, what information does it obtain from the GPS/ADC

A
  • TAS
  • Baro-alt
  • Pressure alt
  • Air data valid
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41
Q

GPS satellite page; what do these stand for?
- SV
- CN
- FC
- ST

A
  • SV: space vehicle #
  • CN: Carrier to noise ratio (5 is norm)
  • FC: frequency used & code
  • ST: Channel state
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42
Q

What does GPS RAIM do for the aircraft

A
  • asses the a/c ability to operate under RNP constraints. If outside of limits, FMF will alert the crew.
  • Predicts availability of adequate GPS satellite coverage along the route
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43
Q

What is something to note when calculating GPS predictive RAIM

A

The FMS will not predict past 0000z

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44
Q

What is automatic RAIM prediction?

A

When 2nm inbound to the FAF, the FMF automatically determines the predicted RAIM availability & position error at the FAF & MAPP & will alert if outside of tolerances/RAIM is not available

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45
Q

How to check the RAIM status of any fix or waypoint

A

Predictive RAIM page

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46
Q

How to check RAIM status for entire route & what information is required?

A

Flight plan RAIM page
- operational GPS
- route is active
- Perf is initialised
- ETD date & time are entered
- a/c is not airborne
- Predictive RAIM is not being computed

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47
Q

What to do if a RAIM WNG comes up in RNP asx?

A

Crew must deselect the current active GPS & allow the FMF to choose the next best solution

48
Q

What is RNP

A

Required navigation performance
- provides estimates of the ability of the a/c to maintain is flight path within the prescribed limits

49
Q

What two measures can be used to compare against RNP containment limit

A

ANP (actual navigation performance)
TSE (total system error)

50
Q

When will you get;
the RNP UNABLE condition
The RNP EXCEED condition

A
  • the RNP UNABLE condition: when ANP is greater than the containment limit OR loss of EGI OR SP
    -The RNP EXCEED condition: When TSE exceeds the value for RNP.
51
Q

What methods of navigation are acceptable for RNP asx?

A
  • GPS
  • GPS/INU
  • INU only
  • INU/RAD
52
Q

What information is combined to produce ANP?
What is ANP directly related to?

A
  • Position estimated error
  • Path definition error
  • Path steering error
    Directly related to EHE
53
Q

What are the 6 reasons for an RNP EXCEED message

A
  • AP not engaged in APP mode
  • ANP > than containment limit (2x RNP)
  • Non WGS-84 datum selected
  • Non dual EGI config
  • Non duel SP config
  • PPS mode is selected
54
Q

What are the default RNP values
- ENR
- TERM
- APPCH

A
  • ENR: RNP 4
  • TERM: RNP 1
  • APPCH: RNP 0.3
55
Q

Where can you find the current RNP value

A

MCDU POS REF PAGE 2/4

56
Q

How does a GPS receiver work

A

The GPS receiver calculates its own position and time based on data received from multiple GPS satellites. Each satellite carries an accurate record of its position and time, and transmits that data to the receiver.

57
Q

what are the 3 component of GPS

A

Ground
Space
User

58
Q

What does the below give you?
1 sat
2 sat
3 sat
4 sat
5 sat

A

1 sat: Nil
2 sat: Nil
3 sat: Position
4 sat: Position & altitude
5 sat: Position, altitude & RAIM

59
Q

What are the 8 SP subsystems

A
  • Controls & displays
  • Flight controls
  • FLT mgmt function
  • Nav radios & sensors
  • Communication radios
  • Datalink radios
  • Surveillance
  • Safety & recording
60
Q

What is the standard operation mode of the SPs

A

Dual mode, one SP is designated as the Master SP, and the other as Standby.

61
Q

What are the main functions of the master SP

A
  • Controls Nav & guidance
  • Bus controller on both 1553 busses
  • Provides FD
  • Controls routing of data
62
Q

In normal SP function, which SPs provide which FD data

A
  • SP1 > AFCP1 > Pilots FD
  • SP2 > AFCP2 > Co pilots FD
63
Q

What do the SPs do in terms of FMS Nav solution

A

each SP will individually compute a navigation solution & will alert the crew if they are different.

64
Q

What are the 3 rules of continuous coordination between the SPs

A
  • STBY SP obtains data from its own inputs
  • If the Master SP cannot obtain data directly, the Stanbdy SP passes the data to the Master & vice versa
  • Each partition is responsible for passing sufficient data to the corresponding off-side partition
65
Q

What decides which SP is designated as master

A

The platform systems through monitoring internal health of each SP. The FMF in the Master SP the assumes the role of master FMF.

66
Q

What are the 2 primary functions of the STBY SP

A

-Computes selected Nav solution to compare against -master SP
- Receives & monitors data from Master SP iot to take over if required

67
Q

What are the two redundancy modes of the SPs

A
  • Dual mode: communicating & coordinated, one is master & other is standby
  • Single mode: SPs are not coordinated but are communicating (degraded mode)
68
Q

What criteria have to be satisfied iot have the SPs operating in dual mode. What will happen if they aren’t?

A
  • SPs have completed initial coord
  • Software versions are identical in both SPs
  • Nav databases are identical

The SPs will enter single mode

69
Q

What does the message SP RESYNC mean
What will occur?

A

occurs when there is a breakdown in coordination between the SPs
The Master SP will automatically initiate a cross load - the message ‘RESYNC IN PROG” will appear.

70
Q

What does the message RESYNC REQUIRED mean?

A

When the SP detects a discrepancy that cannot be resolved by normal resync steps, the FMF declares the standby SP as invalid.
MANUAL RESYNC IS REQUIRED

71
Q

How to manually resync the SPs

A

SYS > FMS CTRL > LSK R5 (will only pop up as an option under these cirumstances)

72
Q

SP redundancy: database management

A

FMF ensures identical navigation & MAGVAR databases are loaded into both SPs

73
Q

SP redundancy:MCDUs

A

When standby SP becomes master SP, MCDU displays are maintained

74
Q

SP redundancy: Display system

A

When standby SP becomes master SP, displays are maintained. (momentary black screens & red Xs)

75
Q

SP redundancy: route planning

A

Route planning is performed by the master SP. Flight plan data & changes are transferred to the standby SP

76
Q

SP redundancy: guidance

A

Only provided by the Master SP.

77
Q

SP redundancy: performance

A

computed by the master SP, initialisation data is also transferred to the standby SP

78
Q

SP redundancy: Comms radios management
& Air-ground data link

A

Master SP manages & controls comms. Data is transferred from master SP to standby SP.

79
Q

What is an ADC failure indicated by?

A
  • a red X through IAS/ALT tapes
  • a yellow X through VSI
  • an IAS or ALT miscompare flag
80
Q

What is an AP failure indicated by?

A
  • uncommanded disconnect
  • failure to connect
  • FP or FD FAIL on PFD
  • AFCPn NOGO on SYS STATUS page
81
Q

What is an FD failure indicated by?

A

FDn flag on top RHS of ADI

82
Q

What is an ICU failure indicated by?

A
  • ICU light on one or more EXCAP station or loss of comms
83
Q

What is an EIDS failure indicated by?

A
  • Loss of a screen
  • Red or yellow X
  • warning flags
84
Q

What is an EGI failure indicated by?

A
  • loss of GPS info
  • Loss of pilot ATT/HDG
  • Loss of AFCP/FDs
  • Loss of RADAR stab
85
Q

NARF?

A

Navigation alignment refining feature mode. (Refines sensor parameters using rotation of the earth)

86
Q

When will VNAV not work

A

> 15nm XTRK

87
Q

Whizz wheel: calc HDG drift & GS for;
TRK 063, wind 140/78, TAS 300kts

A
88
Q

RADALT fail affects what systems?

A

EGPWS, RADAR, TCAS

89
Q

Radar alrimeter is valid to what height

A

2500ft

90
Q

Hazardous areas of navcomm systems;
HF, SATCOM, MSAT, VHF, VUHF, TACAN/IFF/RADALT/TCAS

A

HF: 200ft
SATCOM: 20ft
MSAT: 5ft
VHF: 5ft
VUHF: 1ft
TACAN/IFF/RADALT/TCAS: nil direct contact

91
Q

How can you ident a fail of the ICS

A

ICS light illumination on all excaps (located above ENTER button)

92
Q

What are out available nav solutions
Max theoretical drift rate?

A

Blended INU/GPS
INU only
GPS only
INU/RAD
No nav

Drift: max 0.8nm/hr

93
Q

What is ETAS

A

Effective true airspeed.
Used when increasingly large crosswinds are present - aircraft spends less time moving forward and more time moving sideways.
ETAS computes the true TAS experienced by the A/C when drift is >10deg

94
Q

What does EGI BATT FAIL mean
Actions?

A

The EGI BATTERY has failed, the GPS will not store satellite ephemeris and almanac information, may be slow to align or not align at all.

Initialise the GPS
Enter position/time/date if possible

95
Q

FMS does not display GPS date/time.
Cause?
Corrective action?

A
  • If EGI IBIT is performed when the system date/time is incorrect, the EGR will not be able to report correct time/date
  • corrective action: SOPS 2-15
96
Q

What is PBN

A

Performance Based Navigation, encompassing both Area Navigation (RNAV) and Required Navigation Performance (RNP)

99
Q

What are the Approved PBN Navigation Specifications for use on the C-130H

A

RNAV 10,5,2,1, RNP 4,2,1

100
Q

What does the Nav Mgmt function do?

A

Controls, monitors and evaluates the available nav sources/modes and selects the most accurate for use by the FMF, crew & systems.

101
Q

What does the aircraft navigational state include?

A

Aircraft position, speed, track, drift, attitude and wind data = nav state vector

102
Q

What is an EGI

A

A self-contained, all attitude navigation system (GPS & INU)

103
Q

What does the EGI produce

A

seperate position estimates from its GPS and INS subsystems, as well as a blended solution (which applies GPS based corrections to INS position data)

104
Q

Where are the GPS antenna located?

A

2x on upper at FS320

105
Q

What are the EGIs powered by

A

Both on ISOLATED DC bus, but both also powered by PAVS & CAVS seperately.

106
Q

What are the EGIs powered by

A

Both on ISOLATED DC bus, but both also powered by PAVS & CAVS seperately.

107
Q

What is INU/RAD

A

Solution that uses inputs from the INU and NAVAIDs listed in the database to provide nav state vector.

108
Q

How are the EGIs managed in terms of SP/1553

A

Master SP has direct control of EG1 on 1553 Bus 1 and EGI 2 on Bus 2

109
Q

How are the EGIs managed in terms of SP/1553

A

Master SP has direct control of EG1 on 1553 Bus 1 and EGI 2 on Bus 2

110
Q

What band do the HF radios work
What do they provide

A

2 - 29.999999999MHz
Datalink, Automatic link establishment & SELCAL

111
Q

How do HF radios work

A

transmitted from a base unit into the Earth’s atmosphere. These radio signals ‘bounce’ off the ionosphere and return to land, where they are received by another transceiver tuned into the same radio band

112
Q

How do VHF radios work

A

Also LOS comms
30-300MHz

113
Q

How are HF radios affected

A

In the ionosphere, ionisation (electrons stripped from atoms, producing electrically charged particles), occurs due to solar radiation.
Intensity of solar radiation effects the rate of ionisation of different layers of the ionosphere, therefore, when the sun is hotter (Day), frequency needs to be higher in order to reach the F region, to be refracted without being absorbed by the D region,
At night, frequency can be much lower as the D region no longer exists to attenuate the sky waves.

114
Q

How do UHF radios work

A

UHF radio waves propagate mainly by line of sight and ground reflection. Cannot travel beyond a horizon. radio repeaters are used to continue beyond LOS if required. Used for satellite comms etc.

115
Q

What is the 1553 network made up of

A

2x databusses, each with their own circuit, providing redundancy. 2x bus controllers on each bus, and an SP to each bus.
BUS 1/BC 1/SP 1 = one system
BUS 2/BCC 2/SP2 = another system

116
Q

What will occur if one of the 2 1553 communications lines is severed?

A

comms will go back to the affected bus, which will communicate with the other bus. All TFC will transfer to the second bus.

117
Q

FMSn Fail vs
FMCn Fail

A

Both will cause SINGLE OPERATION scratchpad message

  • FMCn fail is a SFD message which identifies the true/hardware fail of an SP
  • FMSn fail in FMS CTRL page indicates a communication error between the SPs

HERC REVISION (14 decks)

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