737 Flight Management and Navigation

Question 1

What is the function of the FMC Source Select Switch?

Answer 1

BOTH ON L - selects left FMC for all FMC operations

NORMAL
- Left FMC controls CDUs and provides input to the auto throttle system.
- Right FMC operates in synchronization with left FMC
-Maps display composite information from both FMCs

BOTH ON R - selects right FMC for all FMC operations

Question 2

Explain the function of the VHF NAV transfer switch.

Answer 2

NORMAL - VHF navigation from default receiver. In the event of a receiver failure, this switch must be manually positioned to one of the below positions.

BOTH ON 1 or BOTH ON 2 - transfers VHF navigation source to selected receiver

Question 3

Explain the function of the IRS Transfer Switch.

Answer 3

NORMAL - Attitude and heading info from default IRS. In the event of a failure this switch must be manually positioned to one of the below positions.

BOTH ON 1 or BOTH ON 2

Question 4

Explain the meaning of the Amber FMC P/RST alert light on the forward panel.

Answer 4

An alerting message exists for both CDUs.

Question 5

Describe the alert associated with failure of a single FMC.

Answer 5

If the right FMC fails, the amber FMC alert light and the FMC message light will illuminate. The message SINGLE FMC OPERATION will be displayed in both scratchpads.

If the LEFT FMC fails, the FMC alert light will illuminate. The MENU page will appear on both CDUs.

Question 6

What alert indicates that ANP exceeds RNP.

Answer 6

If ANP exceeds the displayed RNP value, the UNABLE REQD NAV/ PRF-RNP message will be displayed on the CDU scratchpad.

ANP and RNP annunciations on the MAP display turn amber

When in the approach environment an additional amber UNABLE REQD NAV/ PRF-RNP will be displayed across the MAP.

Question 7

How are VNAV Speed/Altitude restrictions entered into the FMS

Answer 7

• All speeds are considered “at” restrictions unless modified by the pilot

Speed -
- “A” after the speed means At or above
- “B” after the speed means At or below
- mandatory speeds are entered with no suffix A or B

Altitude is the same principle.

Altitude restrictions between two altitudes are displayed as follows: 220A240B.

Question 8

Explain the meaning of the CDU messages DRAG REQUIRED and DES PATH UNACHIEVABLE displayed during VNAV PATH descent.

Answer 8

DRAG REQUIRED - Airspeed is 10 kts or more above FMC target speed

DES PATH UNACHIEVABLE - the descent profile is too steep for the aircraft

Question 9

Describe the commanded acceleration after takeoff when VNAV is engaged.

Answer 9

• Aircraft will accelerate to the previous MCP speed of V2 + 20 kts until the acceleration height.
• If engine failure is detected it will maintain existing airspeed if that speed is between V2 and V2 + 20kts. If above V2 + 20 it will pitch to maintain V2 +20.
• The flap placard speed minus 5 kts after reaching the acceleration height.
• 230 kts or less until the leading edge flaps are retracted
• After TE flaps are retracted the most restrictive of the following:
  • 250kts
  • Active target speed
  • A waypoint constraint
    -Speed restriction asssociated with origin airport.

Question 10

Explain the meaning of an illuminated GPS light on the IRS Mode Selector Unit. (ISDU)

Answer 10

• Indicates failure of other ? GPS units
• Indicates failure of a single GPS unit when Master Caution recall is initiated.

Question 11

Explain meaning of a flashing ALIGN light on the IRS Mode Selector Unit. (ISDU)

Answer 11

• No present position entry
• Unreasonable present position

Question 12

What warning is there if the IRS system switches from it’s normal AC 115 volt power supply to battery or DC power on the ground?

Answer 12

A horn will sound in the nose wheel well.

Question 13

When the IRS system is turned off what will remain illuminated?

Answer 13

The ALIGN lights on will stay on for about another 30 seconds while the system shuts down.

Question 14

How is a fast align performed on the IRS on a quick turn?

Answer 14

Instead of turning knob to NAV mode turn it to ALIGN mode. Perform entry of GPS coordinates in CDU.

Once the coordinates are in the IRS should be aligned and the knob can be switched to NAV mode like normal.

Question 15

How is IRS normally set up?

Answer 15

Switch knob on IRS to NAV mode. The light will switch to DC ON for about 2 seconds and then will switch to ALIGN.

To aid in the alignment process enter the current GPS coordinates (from left side) into the CDU.