Everything important!!..except Flight Planning Flashcards
Generic INS components
- Accelerometers (A)
- Computers (C)
- Control Display Unit (CDU) (C)
- Stable platform (S)
Advantages of INS
- Self-contained (S)
- Undetectable (U) (doesn’t radiate)
- Unjammable (U)
- All WX operational (W)
- Worldwide operational (W)
- Accurate Px and very accurate attitude (A)
How INS calculates positions?
- Acceleration is measured (in 3 direction)
- Newton’s 2nd Law: for a constant mass, force and acceleration vary inversely
- Integrate a (acceleration) to get v (velocity)
- Integrate v(velocity to get d (displacement)
Mech gyros have been replaced by Ring Laser Gyros (RLG). Reduction in? & Increases in?
Reductions in: 1. Weight/hardware 2. Power consumption 3. Maintenance 4. Cost Increases in: 1. Reliability 2. Service life
Desired characteristics of Accelerometer
- Low threshold of sensitivity
- Wide range of sensitivity
- Linear output
- High resolution
Parts of a simple Gyro
- Rotor (spinning wheel)
- Spin Axis (about which rotor turns)
- Gimbal (support that provides spin ais with a DOF)
Properties of a Gyro
- Rigidity: dependent on angular momentum
2. Precession: movement of the spin axis in response to an external force
2 Main Advantages of INS integration/hybridization
o Improved Accuracy
o ↑ mission completion
2 Main disadvantages of INS integration/hybridization
- Loss of complete self-containment
* Loss of covertness (dependence on external radiation)
Parts of RLG (CT-142 Honeywell)
- Cervit block
- 3 mirrors
- Prism
- Cathode
- Anode
- Inert gas (Ar)
- Photo cells
2 types of error for the RLG?
Error 1: LOCK IN
o Caused by non-perfect optics (back-scattering)
o Can lead to drift rates of 40-50°/hr if left undetected. Largest source of error: mirror quality
o Fixed with dithering
Error 2: DIFFERENTIAL PATH LENGTH
o T° difference between cervit cavities causes a time/phase
o Eliminated by using one cervit cavity for both lasers.
Initialization (10x initial conditions):
- 2 initial posn cords (Lat/Long)
- 2 initial velocities (N & E)
- 3 initial orientations (x,y,z gyros)
- 3 orientations rates
Types of Alignement :
- Self-Alignment (most popular)
- Reference alignment (Rwy heading)
- Moving alignment (carrier based A/C)
- In-flight alignment (ability to align Airborne)
Self-Alignment Sequence:
- Initialization
- Warm-up (alignment performed by computer)
- Coarse levelling
- Coarse alignment
- Fine levelling
- Fine alignment (aka gyro compassing)
High latitude Problems:
- Undetectable tilt preventing initiation of gyro compassing
* Inability to accurately resolve True North
Types of Errors during the alignment
Unbounded (3x): increase with time
• Leveling gyro drift(largest single error in INS)
• Initial Azimuth misalignment (due to operator input)
• Azimuth gyro drift (2nd largest source of total INS error)
Bounded (3x): oscillate about a mean value with time
• Initial levelling (Platform tilt-computer error)
• Accelerometers (acceleration error)
• First integration errors (velocity errors)
Schuler Theory
- Platform with initial tilt error, thinks it’s moving and is torqued to what it ‘’thinks’’ is level.
- Due to this ‘’correction’’ torque applied to the platform, the accelerometer feel a ‘’real’’ component of acceleration due to gravity.
- The platform retilts in the original direction and goes back to where it was and the cycle repeats itself every 84.4 min.
2 Components of Honeywell IRS
Inertial Reference Unit (IRU) & Mode Selector Unit (MSU)
Electrical Requirements of IRS
- Receives AC & DC power from the aircraft and provides switching to primary AC or secondary DC.
- Can operate with either:
- 115V AC ; or
- 28V DC.
Cooling Requirements of IRS
- Cool air provided via A/C air conditioning
* Loss of cool air = shut down of IRU after a specified time.
Modes of Operation of IRS
OFF
ALIGN
NAV
ATTITUDE
Describe ALIGN mode in IRS
- Computes Hdg and latitude by measuring horizontal earth rate components
- Equator (0°) = 2.5 min, 60-70° = 10 min, 70°+ = longer or may fail
Describe NAV mode in IRS
(Can’t do external update in Nav mode) • Provides output to FMS • A/C attitude • Body rates • Body accelerations • True Heading • Velocity vectors • Wind data • Lat/Long • Inertial altitude
Nav components calculate: • Present location • Velocity • Heading • Attitude
Describe ATTITUDE mode in IRS
• NO Nav output provided
Used when:
• MSU fault enunciator illuminates
• After the IRS temporary loss all power
Describe the System Performance Test
- Entered LAT must pass system performance test at end of alignement phase
- LAT entered must be within 30 min of arc of LAT computed by IRU during alignment
- If entered LAT is good to go, alignment is complete and it allows entry into NAV MODE.
IRU feeds ATS. ATS maintains data base of what ?
- True heading
- True Track
- Present Lat/Long
- Inertial G/S
- Wind velocity & direction
- System status
What does ALERT & WARNING sign means in CT-142 Emulated INS
ALERT: 90 sec to next waypoint if on track or 90 sec to abeam position if off track
WARNING:Malfunction is preventing IRU alignment OR a latitude that is inaccurate by more than ½ a degree is entered.
What are the 2 types of Apparent Precession in the GPS?
- Earth Rate: apparent precession of a stationary gyro due to the earth’s rotation wrt space.
- Transport Wander: apparent precession due to the movement of the gyro from one point on the earth to another.
Unique Capabilities of the GPS
3 Very Gross Children Puked Up Red Ants • Highly accurate 3D position • Provides velocity and time • Global coverage • Continuous availability • Passive service (receiver) • Unlimited # of users • Resistant to interference & jamming • Allows common grid reference
What are the 3 distinct parts of the GPS?
Space segment
Control segment
User segment
Describe the Space segment
- 6 to 11 satellites are always in view
- Orbit period ~12hr
- Orbit à 10 900m
Describe the Control segment
- Monitor the health and operating parameters of the satellites
- 1 master control station @ Colorado Springs
- Monitor stations look for errors caused by gravitational pulls (moon & sun) & solar radiation pressure.
- Master Control Station (MCS) periodically sends data to satellites via Nav Data msg
Describe the User segment
• Military & civilian GPS receivers decode and process the GPS satellite signals. Consists of: • Antenna • Computer • Oscillator • Signal processing equipment
What are the 2 navigation services? Describe them.
SPS (Standard Positioning Service): • L1: coarse acquisition • L2: interim for carrier phase • 60-100nm accuracy when SA (selective availability) active PPS (Precise Positioning Service): • L1: coarse acquisition & P/Y code • L2: P/Y code • 16m accuracy • Requires decryption
Describe the C/A code
- Available to all users
- Code is 1023 bits long
- Tx @ 1.023 mbits/sec
- Accuracy = 100m (95% of the time)
- Each satellite has its own unique code
Describe the P code
- 267 days long code (each satellite gets a portion of the code (7 days)
- 10.23mbits/sec
- Accuracy = 16m (95% of time)
- Available to US mil & limited allies
Describe the Y code
• P Code that has been encrypted
What are the operating freq of the GPS?
- Satellite clock freq: 10.23 MHz
- L1 is 154 * 10.23MHz = 1575.42 MHz
- L2 is 120 * 10.23MHz = 1227.6 MHz
Describe the GPS clock
- 1ns = 1ft posn error
- Each satellite has 4 atomic clocks
- Clock drift between updates is predicted and passed to users
Describe the Receiver clock and Pseudo-Ranging
Receiver Clock
• Uses cheap clock (quartz clock)
• Uses pseudo ranging to calculate difference in timing accuracy between satellite and receiver (Clock Bias)
Pseudo Ranging
• 3D position could be established with 3 satellites but due to inherent clock erros in the satellite, we need a 4th to resolve posn using pseudo ranging.
What contains the Navigation Message?
• Contains the info req’d by the receiver to perform the operations & computations req’d to navigate using GPS.
• Message is superimposed over the C/A and P codes
• Divided in 5 sub-frames and it takes 30 sec to receive:
1. Clock correction
2. Ephemeris data
3. Ephemeris data
4. GPS NOTAMs
5. Almanac/Health status
What are the components of the Flight Management System UNS-1C?
2x CDUs (Control & Display unit) • Cockpit centre console • Each has internal GPS receiver • Req. 28V DC and 26V AC power 1x DTU (Data Transfer Unit) • Located Co-Pilot (right knee) • Req. 28V DC 2x ACUs (Air data Converter Unit) • Convert DADC output to a message format for UNS-1c • Req. 28V DC and 26V AC power 2x Glareshield Advisorie • Row of 7 annunciator light set • Only active if AUX mode selected 2x GPS antennas • Aft of cockpit escape hatch Config module • Attaches to CDU • Stores system configuration information
FMS inputs
- AHRS
- DADC
- IRU
- DTU
- GPS
FMS outputs
- Flight Instruments
- FGS (Auto-Pilot)
- IRU
- DTU
How does the UNS-1c do a Position computation?
o Kalman filter blends the 2 GPS positions with the IRU in a statistical model to determine best position
o Doesn’t use input from NavTac or VOR2 receivers
o Can manually deselect doubtful inputs
o FMS will indicate ‘’dominant’’ sensor
Describe GPS-RAIM-HIL (RAIM: Receiver Autonomous Integrity Monitoring)
o 4 Sats→ 3D Position o 5 Sats→ RAIM (bad satellite present) o 6 Sats→ FDE (False Detect Exclude) Ident & Drop bad satellite HIL (Horizontal Integrity limit) • If HIL exceeded→GPS Integ warning Alarm given: • Enroute: HIL > 2nm after 27 sec • Terminal: HIL > 1nm after 7 sec • Approach: HIL > 0.3nm after 7 sec
Talk me through the GPS Process
Satellite Selection
o Uses almanac data and/or entered position, velocity, and time
o Chooses the BEST 4 satellites
Searching the Sky
o Receiver picks a sat & search for its unique C/A code
o Once one is found, it looks for others in the vicinity
Satellite Acquisition
o Estimates phase shift req’d for time diff and Doppler shift req’d for relative speeds (Allows reception of weaker signal)
o Locks onto the signals
Needed to commences Navigation
o Required satellites (4+), clock bias, nav message
Code Tracking Loop
o Tracks phase shift caused by time difference
Carrier Tracking Loop
o Tracks Doppler Shifts caused by relative speed changes
What is GPS #1 Error?
GPS #1 error: User Radial Error (URE)
o An error in the measurement of the distance from satellite to receiver
• SATELLITE: time error = up to 3.3m (95% of time)
• CONTROL: inaccurate ephemeris data = up to 4.2m (95% of time)
• RECEIVER LARGEST of URE: (Atmospheric Modeling is the largest cause of error):
Ionosphere
Troposphere
Multi-path error (antenna location/vehicle dynamics
What is GPS #2 Error?
GPS #2 error: Dilution of Precision (DoP)
o Comes from having less than perfect geometry
o DoP is 2.54, 95% of the time
What is the Total system accuracy of the GPS?
o P Code = 16.8m 95% of time (2.54*6.6)
o C/A Code = 35.3m 95% of time (2.54*13.9)
What are the different receiver types?
o Sequential: 1 or more channels o Multiplex: 1 or more channels + software channels o Continuous (THE BEST): 4 or more channels
What are the GPS Inputs ( Aircraft GPS to Emulated GPS) ?
o GPS Position o Time o Satellite Info o System status o Altitude o Ground speed o Ground track o IRU to Emulated GPS = TAS (from DADC)
What are the GPS Ouputs (Emulated GPS to User interface →LCD Displays)?
o Position & time o Satellite info (Visible & tracking info) o Altitude o Ground track o Ground speed o TAS
What can display the TDS?
o Fly to Points (FTPs) o Contacts o Reference narks o Vectors o SAR patterns o Free form graphics o Range circles
What are the sources for TDS?
- GPS (default)
- INS
- DR (doesn’t update automatically, i.e. good until you turn)
Give the different function of the TDS
1. FTPs: Calculate track, Time to go, Distance to go • Types: • Flight Plan • Intercept • Normal • Monitor 2. Reference Marks • 50 max per console • Used to mark ETP aerodrome, destination or alternate aerodromes, ETP on track 3. Line (Fixed Vector) • Lat/Long to Lat/Long 4. Line (Normal Vector) • Aircraft to Lat/Long 5. Circles • Max of 5 6. RADAR circle • Shows LOS range for the A/C 7. SAR Patterns • To plan, fly and monitor
What are the 3 components of the ADF?
1) ADF receiver
2) Antenna
3) RMI
Explain the operation of ADF
- Low/med f receiver with a directional and fixed antenna
- Receive signal from NDBs and commercial radio stations
- Indicates continuous compass bearings to a transmitter which are indicated on an RMI
- Readings to TRUE bearing must be corrected for Dev + Var
- Interference from atmospheric noise and thunderstorm due to f band, and A/C electric field and structure.
- Ground wave may be contaminated by sky wave.
- Accuracy = +/- 3 degree for 1 CFFTS (30 degree under poor conditions)
- Range up to 200nm (200KHz) – 50nm (1600KHz) and decreases at night (Sky wave contamination)
What are the 4 component of the ADF on the CT-142?
1) Radio compass receiver (Avionics rack)
2) CDU (x2 center console)
3) Antennas (under A/C)
4) Bearing indicators (Pilot, Co-pilot, ACSOs)
Operating limits of the ADF on CT-142
f range 190,0-1799,0 KHz
2) Can also receive noise on continuous wave transmission on Int’l distress f 2182 and provide relative bearing to crash site.
What are the principles of operation for the VOR (VHF omni directional range)?
1) Airborne reception receives 2x 30Hz signals from VOR ground station, measure phase dif., converts phase dif. to a radial which is displayed on RMI.
2) Aligned to MAG (SDA) and TRUE (NDA)
3) Accuracy limitations: +/- 2°–5° (Theorical) 1CFFTS accepts +/- 2.5 degree
4) LOS
5) Affected by variety of effects = Echos from hills and bldgs & Mag anomalies
6) 80° cone of confusion
7) VHF: 108.00-117.95 MHz (50KHz spacing)
8) ILS: 108.10-111.95 loc (VHF) // 330.95-334,70 glideslope (UHF)
Explain what the VOT is
1) Avail at most major airports
2) Transmit a test signal to allow functional inspection of VOR receiver without knowing your location on specific radial
3) Both signal are in phase (000 degree radial on RMI)
4) ATIS on same f.
What are the capabilities & limitations of the TACAN and DME?
1) range is LOS (UHF)
2) Max of 252 users (126 mode ‘X’ & 126 on mode ‘Y’)
3) Cone of confusion varies (60-110°)
4) Bearing accuracy +/- 0.75°
5) DME is slant range, accurate +/- 1nm
6) Aligned to MAG (SDA) & TRUE (NDA)
Describe the principles of operation of the TACAN
1) Components: Radial calculations (Azimuth) & DME calculations (Distance)
2) Radial calc ≠ same as ADF/VOR & DME calc = slant range
Describe the TACAN on CT-142
- CT-142 has a SINGLE TACAN system
1) TACAN antenna located upper + lower fuselage
2) TACAN system is in secondary avionics rack
3) NAV TAC controller located on pilot side
What are the 3 sources of position lines?
1) Visual
2) Electronic (Navaids/radar)
3) Celestial
What are the different types of position lines?
1) Straight (ADF, VOR, TACAN, RADAR bearings)
2) Curved (DME, RADAR only)
Explain how to do a fix with an ADF
1) Tune
2) Identify station (Morse and expected needle)
3) Read tail to have COMPASS bearing from station
4) Convert to TRUE bearing (Variation = position & Deviation = ADFI 1 and 2)
5) If needle oscillates >5 Degree, not valid anymore
Explain how to do a fix with a VOR/TACAN
1) Tune
2) Identify station (Morse code and expected needle)
3) Read tail to have MAG bearing of A/C from stn
4) Plot on map by aligning protractor with MAG North at the stn.
Explain how to do a radar fix
1) Identify radar point
2) Read cursor info to give relative bearing of A/C from point (+2 -2)
3) Convert to TRUE bearing by adding TRUE heading (based on compass heading, dev, var at A/C px)
4) Plot using local meridian at A/C DR Position
What are the single lines uses?
1) Homing: fly the needle, don’t apply the drift
2) Tracking: Apply Drift to needle (used at 1 CFFTS)**
What are the advantages of cruise control?
1) Increase safety and efficiency
2) Conservation fuel on ferry flights
3) Optimize payload
4) Saving on fuel in long range tactical flights
5) Efficiency fuel conservation on a long range flight where max range is required
6) Controls may be adjusted in flight
What are the factors that affect cruise control?
1) En-route weather
2) W/C
3) T°
4) Fuel capacity
5) Fuel availability
6) Amount of fuel reserve req’d
7) Max T/O and Min landing weight
8) Payload
9) Distance
10) ATC restrictions
Define Endurance
Operation of A/C at a specific speed and altitude to achieve the lowest Fuel Flow and thus, MAX time A/B.
Define range
Operation of A/C at a specific speed and altitude to achieve MAX ground range per pound of fuel, for a given fuel load.
Describe the Specific Fuel Consumption (SFC)
Ratio of fuel used to the amount of thrust produced.
1) SFC measures the efficiency of an engine
2) The lower the SFC, the better
3) Turbo jets: SFC = Fuel Flow/Thrust
4) Turbo prop: SFC = Fuel Flow/ESHP (Effective Shaft Horsepower)
5) Variables:
a. Altitude
b. Engine RPM
c. IAS
d. OAT
Variables VS. ESHP
↗Alt = ↘ESHP
↗Engine RPM = ↗ESHP
↗IAS = ↗ESHP
↗OAT = ↘ESHP
Variables VS. SFC
↗Alt = ↘SFC then ↗SFC
Optimum RPM = ↘SFC
↗IAS = ↘SFC
↗OAT = ↗SFC
What to keep in mind for MAX RANGE?
1) Alt: Fly high
2) Eng RPM: operate engines at max continuous RPM
3) IAS: Fly Long Range Cruise speed (LRC)
4) OAT: Can’t do much about this one!
Why is it important to manage fuel?
1) Ensure enough fuel for mission
2) Detect early a fuel leak
3) Check if fuel consumption matches predicted consumption
4) Be aware of remaining fuel in order to respond to diversion/re-task (Search and Rescue mission)
What is Specific Air Range (SAR)?
Measure of efficiency with which an A/C fly through the air.
SAR = TAS/Fuel Flow
What is Specific Ground Range (SGR)?
Measure of efficiency with which an A/C fly over the ground.
SGR = Ground Speed/Fuel Flow
Ex.:
G/S = 195
FF = 880 lbs/h
SGR = 195/880 = 0.221 nm/1lb of fuel = 221 nm/ 1000 lbs of fuel
How to do a fuel analysis?
1) Obtain fuel read from pilot
2) Compare actual to expected performance (HOWGOZIT)
3) Compare flight environment to expected environment
4) If req’d, take corrective action.
What are the factors that causes changes in consumption?
1) IAS condition not as planned
2) Winds dif. From planed
3) Wx avoidance
4) Fuel leak
5) A/C performance is dif. than expected
6) ATC re-routing
What are the corrective actions for fuel management?
1) Change A/C speed to LRC (FF improvement)
2) Change altitude (wind or FF may improve)
3) Change Alternate (↘ min div fuel)
4) Change route (Cut a corner for shorter distance)
5) Change destination
Describe the Terminal Area of CYWG
Class D airspace
• 7 nm around A/D center = below 3000’ ASL
• 12 nm around VORTAC = 2000’-12 500’ ASL
• 35 nm around VORTAC = 3000’-12 500’ ASL
• Extension to 55 nm over Portage = 3000’-7000’ASL
Class E airspace
• Outside of 70 nm = 7000-12 500’ ASL
Class B airspace
• Above 12 500’ to 18 000’ ASL (not included)
• 35 nm around YWG
Why is Aircraft Ranges important?
Flights often require calculation to determine distances that are crucial to the success of the operation or safety of the flight.
What are 2 common ranges?
a. Radius of action
b. Point of safe return
Define Radius of Action
• Max ground distance that an A/C can travel from a datum before returning to that same datum within a specified time
Formula method: T = PH/O+H
T=Time out, P = Patrol Time, O=G/S out, H=G/S home
Define Point of Safe Return (PSR)
A point beyond which an A/C cannot fly and return to its own or same other associated base within safe limit of endurance (SLE).
**AT 1 CFFTS SLE = Total endurance – 1500lbs (90 min
T = (SLE)H/O+H where T= time to PSR
Define ETPs
• A point on the intended track from which it will take the same amount of time to fly to either critical point A/D.
What are the steps to build ETPs?
- Draw line between ETP A/D. Find middle and bisect it.
- Your approx. ETP is where it cut the track
- Measure distance between ETP and both A/D (should be the same). Using reduced TAS (160 kts) calculate the still air time to fly this distance
- Using 10 000’ winds(9000’), avg between each ETP A/D, plot a wind vector for the amount of time found in step 3.
- Join the ends of the two points found and construct a right bisector on that line.
- Your ETP is where it cut the track.
* *Why 10 000’ & 160 Kts?: Because depressurization and loss of 1 engine.
What are the Aerodrome requirements for ETP?
- 3000’ long, 100’ wide, hard surface with usable fuel
- NOTAMs must be considered
- CRFI, de-icing, power cart
- Forecast Wx must be at or above published landing minima for the approach aid serving the rwy from 1 hour before earliest ETA to 1 hour after latest ETA.
