Allegiant A320 - Navigation
Terms in this set (60)
What is an ADIRU?
It is a combination of an Air Data Reference (ADR) unit and an Inertial Reference Unit (IRU)
What is the purpose of the IRUs?
To provide the aircraft with attitude, heading, track, speed and present position.
What is the basic operation of the IRUs?
Each IRU utilizes a set of ring laser gyros to sense rotation about the aircraft's three axes and accelerometers to sense g-force and changes in velocity. The IRUs are aligned prior to each flight.
What other position data do the IRUs utilize to calculate the aircraft's present position?
They utilize radio navigation data and GPS data to calculate a hybrid GPIRS position.
What is the basic operation of the ADRs?
Receiving data from the pitot static system the ADRs provide the aircraft with airspeed, mach, barometric altitude and backup vertical speed information.
In normal operations to which PFD and ND do each ADR provide data?
ADR 1 - Captain's PFD and ND
ADR 2 - First Officer's PFD and ND
ADR 3 - backup
In normal operations to which PFD and ND do each IRU provide data?
IRU 1 - Captain's PFD and ND
IRU 2 - First Officer's PFD and ND
IRU 3 - backup
How is the switching to a backup ADR or IRU accomplished?
By use of the switching panel.
Use the AIR DATA selector to switch to the backup ADR.
Use the ATT HDG selector to switch to the backup IRU.
How is IRU alignment initiated?
By selecting the ADIRU selector to NAV
How can the flight crew determine the IRU alignment process has started? Finished? How long does it take for the normal alignment?
When NAV is selected, the 10 minute alignment process is started, the "ALIGN" light illuminates and an ECAM "IRS IN ALIGN" memo is displayed. When complete, the "ALIGN" light extinguishes and the ECAM memo is cleared.
During alignment, how does the crew normally enter the present position information to all three IRUs?
On the INIT page of the MCDU
During an IRU alignment, what happens if more than 9 minutes have elapsed since the IRU alignment was initiated and no present position information has been entered?
The white "ALIGN" light will flash, reminding the pilot to enter the present position.
During IRU alignment, what is another reason the white "ALIGN" light will flash?
1. IRU alignment fault. Aircraft movement during alignment
2. If the alignment present position coordinates differ by more than 1 degree (60 nm) from the IRU present position memory, then the white "ALIGN" light will flash to alert the crew to verify the coordinates. A second selection of the present position coordinates will continue the alignment.
How is an IRU quick realignment initiated?
By turning all three IRUs OFF and back to NAV within 5 seconds. This starts a quick 3 minute realignment. This is only possible if electrical power to the IRU has not been interrupted.
How are the ADIRUs powered?
The ADIRUs primarily use AC power, with DC battery power as a backup
What indications do the crew have that one or more ADIRUs have lost AC power and are operating on DC battery power?
The "ON BAT" light illuminates. And on the ground, the external warning horn sounds.
During normal ADIRU operations, when would the "ON BAT" light be illuminated?
The "ON BAT" light illuminates for 5 seconds after going from OFF to NAV. This verifies the IRU can operate on aircraft battery power.
If the IRUs are operating on DC battery power, what happens after 5 minutes?
IRU 2 and 3 are automatically shutdown.
When does the IRU fault light illuminate steady?
When a total failure of the IRU has occurred
When does the IRU fault light flash?
When a partial failure of the IRU has occurred. Present position from the IRU is lost for the remainder of the flight. Attitude and heading information may be restored.
In the event of a partial failure of the IRU, what is the procedure to restore attitude information?
The selector must be pulled out and moved from NAV to ATT. The aircraft attitude should remain straight and level with constant airspeed during the in flight alignment (approx 30 seconds).
What does an amber ADR FAULT light indicate?
A failure of the ADR
How do you turn off the ADR without turning off the IRU?
By selecting the ADR pb to OFF.
What would be lost on the Captain's PFD if IRU 1 failed?
Attitude and heading information
What action would recover the attitude and heading information on the Captain's PFD in the event of an IRU 1 failure?
Selecting CAPT 3 on Switching panel ATT/HDG selector
What would be lost on the Captain's PFD if ADR 1 failed?
Airspeed and altitude information
What action would recover the airspeed and altitude information on the Captain's PFD in the event of an ADR 1 failure?
Selecting CAPT 3 on Switching panel AIR DATA selector
How many GPS satellites must be tracked so the aircraft's 3-dimensional position can be determined?
Four or more.
In normal operations, in what mode are the GPS receivers operating?
NAV mode. The receivers are tracking at least four satellites and continually provide position data to the ADIRS / FMGC.
Which MCDU page allows the pilot to deselect Nav Aids such as the GPS?
What happens if one GPS fails?
The ADIRUs automatically get GPS data from the remaining GPS.
How many VOR receivers are installed?
What is the normal method the pilot will use to select a VOR station?
Entry to the RAD NAV page of the MCDU.
How many DME receivers are installed?
How many channels are in each DME receiver?
3 - FMS radio position updating
1 - VOR-DME display
1 - ILS-DME display
How many ILS receivers are installed?
Note: both ILS receivers are always tuned to the same frequency
How is the ILS information displayed on the PFD?
By pressing the LS pb on the EFIS panel
When is a flashing amber "ILS" displayed in the bottom right hand corner of the PFD?
1. ILS approach entered in the MCDU
2. FCU panel APPR pb is armed
3. EFIS panel LS pb is not selected
If the ND Nav Selector is positioned to the ILS position, which ILS receiver will be displayed?
The off-side ILS receiver
In the event of a dual FMGC failure, how are the navigation receivers manually tuned?
By using the STBY NAV tuning on the Radio Management Panel (RMP)
By looking at the ND, how can the pilot determine if a navigation receiver has been automatically tuned, manually tuned on the MCDU or manually tuned via the RMP?
The method used to tune VOR/DME navaids is displayed on the ND using the following symbols:
- no symbol indicates auto tuning
- an "M" symbol indicates manual tuning
- an "R" symbol indicates STBY NAV tuning using the RMPs
If an RMP is used to tune the ILS, which ILS receivers are tuned to the selected frequency?
Both ILS receivers
If an RMP is used to tune the VOR, which VOR receiver is tuned to the selected frequency?
The associated VOR receiver
How many Radio Altimeters are installed?
When is the Radio Altimeter height information automatically displayed on the PFDs?
Below 2500 feet AGL
How many transponders are installed?
What are the primary functions of the radar system?
1. weather avoidance
2. turbulence detection
3. terrain mapping
4. predictive windshear detection
Weather radar is displayed on which screen?
What would prevent the radar display on the ND?
1. ND mode selector in PLAN, or
2. TERR selected ON
The weather radar tilt is based upon what?
What do the colors of the radar images indicate?
Black - min intensity
Green - low intensity
Amber - moderate intensity
Red - high intensity
Magenta - significant turbulence
At what range is the weather radar TURB mode available?
At ranges of 40 nm or less
When is predictive windshear (PWS) active?
1. PWS switch in AUTO
2. Aircraft below 2300 ft AGL
3. ATC switch is ON or AUTO
4. Either engine running
Below what altitude are PWS warnings and cautions displayed and announced?
Below 1500 feet AGL
The PWS system scans the airspace within a range of how many miles ahead of the aircraft?
PWS Cautions are provided in what range?
Below 1200 feet AGL, from 1.5 to 3.0 nm ahead of the aircraft and within +/- 25 degrees either side.
PWS Warnings are provided in what range?
Below 1200 feet AGL, from 0.0 to 1.5 nm ahead of the aircraft and within approximately +/- 0.25 nm either side.
On final approach, the PWS Warnings are downgraded to Cautions below what altitude?
Below 370 feet AGL
PWS alerts are inhibited on takeoff (above 100 kts) and landing below what altitude?
50 feet AGL
On the takeoff roll, below 100 kts, PWS Warnings and Cautions are available out to what range?
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