Systems - Flight Management, Navigation

Question 1

How many GPS receivers are available?

Answer 1

• Left GPS and Right GPS receiver Both GPS receivers are independent and supply very accurate position data to the IRS.
• The IRS in turn supplies a very accurate hybrid GPS inertial position to the FMC.
• If the IRS becomes inoperative, the GPS supplies position and track datar directly to the FMC.
• All GPS tunning is automatic.

Question 2

What does the IRS provide?

Answer 2

• The IRS calculates airplane’s airspeed, attitude, heading and position, provides data for the display FMS, flight control, engine control, and other systems.

Question 3

What are the main components of the IRS?

Answer 3

• IRUs (Inertial Reference Unit)
• AHRUs (Attitude and Heading Reference Unit)

Question 4

What does the IRU provide?

Answer 4

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- The IRU combines inertial reference functions with GPS position information to provide hybrid GPS inertial position outputs.

Question 5

What does the AHRU provide?

Answer 5

• The AHRU provides a stable source of attitude, Heading and rate information used in voted solutions for flight controls. displays, and other using systems.
• Although AHRUs do not have the ability to provide an independent intertial position they do contribute to a hybrid GPS inertial position that combines the accuracy of the GPS position with the stability of the AHRUs inertial sensors.

Question 6

If both of the IRSs fail (meaning both AHRUs and both IRUs), what provides POSITION, HEADING, and ATTITUDE information?

Answer 6

• POSITION: Directly from GPS
• HEADING: Manually set on the CDU POS INIT page
• ATTITUDE: ISFD

The EICAS caution message NAV INERTIAL SYS is displayed.

Question 7

What happens if an IRU fails?

Answer 7

• Should both IRUs fail the FMC will continue to receive hybrid GPS Inertial position solution, using the AHRUs Inertial sensors combine with GPS.

Question 8

Can we recover the IRU if it is lost in flight?

Answer 8

• Inflight alignments allow the IRU to recover from a inflight loss of alignment due to a power interruption or inadvertent shutdown.
• Attitude information becomes available within a few seconds and full navigation capability is restored within 10 minutes, this capability relies on GPS data.

Question 9

What does the ADRS provide?

Answer 9

ADRS provide Airplane altitude and Air speeds for:
* Displays
* Flight control,
* FMS,
* Engine control and,
* Other aircraft systems.

Question 10

From where does the ADRS (Air Datar Reference System) get its information?

Answer 10

• 3 pitot probes
• 6 static ports
• 2 Angle of attack vanes (AOA)
• 1 Total Air Temperature (TAT)
• Engine TAT sensors

Question 11

If the ADRS fails, what provides speed and altitude information?

Answer 11

• SPEED: AOA
• ALTITUDE: GPS

Question 12

What are ADMs?

Answer 12

• Air Data Modules remote sensors that convert the sensed analog pressures to digital values for the air data functions within the ADRS.
• There are 6 ADMS

Question 13

From where does the ISFD get its information?

Answer 13

• Center pitot static system
• Altitude, attitude, and airspeed are independent of IRU and AHRU values.

Question 14

What happens in the event of both voted (ADRS) and backup air data being unavailable?

Answer 14

• ISFD altitude (ISFD ALT) displayed on PFDs
• ISFD airspeed (ISFD SPD) displayed on PFDs