Flight Management and Navigation

Question 1

What information do the IRSs provide?

Answer 1

Attitude, heading and position information (including groundspeed)
SH 11.010 pg 10

Question 2

Are the IRSs dependent on, or independent of, external navigation aids?

Answer 2

Independent

SH 11.010 pg 10

Question 3

How is the GPS activated and what does it provide data for?

Answer 3

GPS is always on when aircraft is powered
provides an accurate aircraft geographical position to the FMC and other aircraft systems.
GPS operation is automatic.
SH 11.010 pg 19

Question 4

With the FMC SOURCE select switch in NORMAL, which FMC is primary and what does it
control?

Answer 4

L FMC is PRIMARY and provides information for CDUs and autothrottles
SH 11.020 pg 3

Question 5

Describe the criteria for airports included in the nav database.

Answer 5

PAVED
5000x100ft runway

Instrument approach (though there are exceptions to this)
SH 11.020 pg 15

Question 6

When using the Autothrottle system, how are reference thrust limits calculated, and how is
thrust equalization maintained?

Answer 6

reference thrust limits calculated by the FMC
thrust equalization maintained through the electronic engine controls (EEC)
SH 11.020 pg 17

Question 7

How are the FMCs operated?

Answer 7

Uses flight plan information entered by the Crew into the MCDU
Left is master
Left shares data with the Right
Controls the A/T
Provides information to the Display Units
SH 11.020 pg 3

Question 8

Where do the FMCs receive their inertial data from?

Answer 8

The IRS through their on-side ADIRU (ex left ADIRU to left FMC

If the on-side ADIRU malfunctions or it is in the ATT or ALIGN mode, the FMC uses the data from the other ADIRU.

SH 11.020 pg 2

Question 9

What does the FMC use to determine position?

Answer 9

In this order:
GPS
--->IRS
------->Ground based navaids (except for ADF)
SH 11.010 pg 19

Question 10

If GPS data is not available, how does the FMC calculate the present position?

Answer 10

IRS then ground based navaids
If GPS data is not available, the FMC calculates the present position based on IRS data.
SH 11.030 pg 5

Question 11

FMC position updates from navigation sensor positions are used in what priority order?

Answer 11

FMC position updates from navigation sensor positions are used in the 
following priority order:
- GPS
- two or more DME stations
- one VOR with a co-located DME
- one localizer and co-located DME
- one localizer 
NOTE: DME updating is defaulted OFF
SH 11.030 pg 5

Question 12

How does the FMC calculate a descent path during a VNAV PTH descent?

Answer 12

Starts at the bottom of descent and works backward, taking into account altitude and speed constraints and restraints for an idle descent, factoring in preset winds and anti ice
SH 11.030 pg 19

Question 13

How can you further reduce a derated takeoff?

Answer 13

Select a derated setting in FMC and use an assumed temp to further derate
SH 11.020 pg 18

Question 14

What is the lateral navigation (LNAV) intercept criteria?

Answer 14

Inside 3 miles it will automatically intercept
Outside 3nm you must be:
- Intercept angle less than 90deg to the course with a valid TO waypoint

Question 15

When does IRS position and ground speed information become available and up to how long
could it take?

Answer 15

after it is aligned
Alignment time varies from 5 to 17 minutes depending on the aircraft latitude
High latitude could take up to 17 minutes
SH 11.010 pg 17

Question 16

When does an ALIGN (white) light illuminate steady?

Answer 16

Respective IRS is in:
ALIGN mode
Initial ATT mode, or
Shutdown cycle
SH 11.010 pg 12

Question 17

What does a flashing ALIGN light (white) on the IRS panel during preflight indicate?

Answer 17

• Fault in alignment process
• Gross error with position entry
• No position has been entered
• contradictory to last known position

SH 11.010 pg 12

Question 18

If IRS AC power has failed, how long can the right IRS operate?

Answer 18

5 minutes then you’ll still have 60 min on the left IRS
You would see an ON DC light
SH 11.010 pg 17

Question 19

On the Boeing 737-NG, how many GPS receivers are installed?

Answer 19

2 GPS receivers

SH 11.010 pg 19

Question 20

What will happen if both ON DC lights (amber) lights illuminate?

Answer 20

Means that the IRS is on DC power (battery power).

After 5 minutes, right IRS will shut down and the left will stay powered as long as batteries are providing power (about 60 minutes)

SH 11.010 pg 17

Question 21

What could cause the call horn in the nose wheel well to sound while the aircraft is on the
ground?

Answer 21

IRS is on battery power alerting that a battery drain condition exists
SH 11.010 pg 12

Question 22

If position information while programming the FMC CDU on the ground is contradictory, what
indication, if any, will alert the crew to this?

Answer 22

Flashing white ALIGN light

SH 11.010 pg 12