Flight Instruments

Question 1

What is the purpose of the Display Processing Computers (DPCs)?

Answer 1

Each DPC interfaces with aircraft subsystems and sensors to collect data. The collected data is then processed and displayed on the Flight Deck DUs.

Question 2

How are outboard Display Unit failures automatically handled?

Answer 2

When an outboard DU failure is sensed, the displays will automatically reconfigure to ensure that each pilot has a PFD, and that an Engine Display is shown.

Question 3

How are the standby instruments provided airspeed and altitude information?

Answer 3

Airspeed and altitude are computed from pneumatic pressure data provided by direct connections to the auxiliary pitot and alternate static sources.

Question 4

How is inertial position and track data provided to the FMC?

Answer 4

The Air Data Inertial Reference System (ADIRS) produces flight data such as position, speed, altitude, and attitude for the flight displays, flight management computers, flight controls, engine controls, and all other systems requiring inertial and air data.

Question 5

How is maximum operating speed indicated on the PFD?

Answer 5

Maximum Operating Speed (red and black vertical band). Bottom of the bar indicates the maximum speed as limited by the lowest of the following: • VMO/MMO • landing gear placard speed • flap placard speed.

Question 6

What does the VNAV speed band on the PFD indicate?

Answer 6

The VNAV Speed Band (magenta) indicates the FMC target airspeed during VNAV PTH descents. The bottom of the bar indicates the autothrottle wake-up speed. The top of the bar indicates the speed at which VNAV will change VNAV PTH to VNAV SPD.

Question 7

When do the Pitch Limit Indicators (PLIs) display?

Answer 7

The Pitch Limit Indication (amber) indicates pitch limit (stick shaker activation for existing flight conditions). • displayed when the flaps are not up • displayed at slow speeds with the flaps up. They look like bushy eyebrows.

Question 8

How is flight path angle and drift angle displayed on the PFD?

Answer 8

The Flight Path Vector (FPV) Indication (white) displays flight path angle and drift when selected on the EFIS control panel: • flight path angle is displayed relative to the horizon line • drift angle is displayed relative to display center.

Question 9

How is standard pressure set on the altimeter?

Answer 9

By pressing the Barometric Standard (STD) switch on the respective EFIS control panel.

Question 10

What does the ALT DISAGREE alert indicate?

Answer 10

Indicates the Captain’s (left) and First Officer’s (right) altitude values disagree by greater than 200 ft for more than 5 seconds. The alert is shown on both PFDs and does not indicate which altitude value is erroneous.

Question 11

What does the IAS DISAGREE alert indicate?

Answer 11

Indicates the Captain’s (left) and First Officer’s (right) airspeed values disagree by greater than 5 kts for more than 5 seconds. The alert is shown on both PFDs and does not indicate which airspeed value is erroneous.

Question 12

What does the AOA DISAGREE alert indicate?

Answer 12

Indicates the Captain’s (left) and First Officer’s (right) pitch disagree by more than 10 degrees for more than 10 seconds.

Question 13

What does the solid green dot along the vertical flight path vector of the Vertical Situation Display (VSD) indicate?

Answer 13

Its called the Range to Target speed dot. Indicates where the aircraft will achieve the FMC or MCP target speed. If the aircraft is within 5 kts of the target speed the dot will be blanked. If the aircraft increases 10 kts or more faster than the target speed the dot will reappear.

Question 14

At what altitudes are decision gates on the VSD provided?

Answer 14

Decision Gates (white, amber) – Displayed on the FMC approach glide path angle line or 3° reference line at 500 ft and 1000 ft above field elevation.

Question 15

How is the HGS system controlled?

Answer 15

The HGS is controlled from a menu within the MCDU.

Question 16

What standby instrument(s) are available?

Answer 16

The standby flight instruments include a standby magnetic compass and an Integrated Standby Flight Display (ISFD). The ISFD displays attitude, airspeed, altitude, localizer/glideslope deviation, and magnetic heading information.

Question 17

How is the Integrated Standby Flight Display (ISFD) powered?

Answer 17

Normally by the battery bus. The ISFD contains an independent battery pack charged by the battery bus. Should the battery bus no longer be energized, the battery pack can power the ISFD for approximately 150 minutes with the BAT switch on. Turning the BAT switch off removes the ISFD from the circuit and removes all power from the ISFD.

Question 18

Which displays utilize failure flags to display instrument failures?

Answer 18

The flag replaces the appropriate display to indicate system failure. The flag is amber text indicating what system has failed.

Both the PFD and NAV displays use amber symbology.

Question 19

How many GPS receivers are installed?

Answer 19

Two GPS sensors in the MMRs receive GPS satellite signals, left and right. The left and right GPS sensors are independent, and each provides an accurate raw GPS position to the FMC, ADIRU, and other aircraft systems.

Question 20

Are IRS outputs independent of external navigation aids?

Answer 20

IRS outputs are independent of external navigation aids.

Question 21

What is indicated by a white ALIGN light on the IRS panel?

Answer 21

The ALIGN light illuminates steady when the respective IRS is operating in either the: • ALIGN mode, • initial ATT mode, or • shutdown cycle.

Question 22

What is indicated by a white flashing ALIGN light on the IRS panel?

Answer 22

The ALIGN light will flash when alignment cannot be completed due to IRS detection of: • significant difference between previous and entered positions or an unreasonable present position entry, or • no present position entry.

Question 23

What does an illuminated FAULT light on the IRS panel indicate?

Answer 23

The FAULT light illuminates if a system fault affecting the related IRS ATT and/or NAV modes has been detected. The illumination of the FAULT light will cause the IRS System Annunciator and MASTER CAUTION lights to illuminate.

Question 24

What does the illumination of an ON DC light on the IRS panel indicate?

Answer 24

The ON DC light illuminates if the related IRS is operating on DC power from the switched hot battery bus (AC power not normal). If this occurs while the aircraft is on the ground, the call horn in the nose wheel well sounds, providing an alert that a battery drain condition exists. Illumination of the ON DC light causes the IRS System Annunciator and MASTER CAUTION lights to illuminate.

Question 25

How long can the right IRS operate without AC electrical power?

Answer 25

Backup DC power to the right IRS is automatically terminated if AC power is not restored within 5 minutes.

Question 26

How long does a full IRS alignment take?

Answer 26

Alignment time varies from 5 to 17 minutes depending on aircraft latitude.

Question 27

What is Automatic Navigation Realignment (ANR) and when does it activate?

Answer 27

When a fast realignment is initiated or the aircraft parks after a flight and remains motionless for at least 7.5 to 15 minutes with the ADIRUs still in the NAV mode and valid GPS data available, the Automatic Navigation Realignment (ANR) mode will perform a complete realignment automatically. The ADIRU’s position (latitude/longitude) will reset and inertial states (i.e., attitude, heading, and horizontal velocities) will reset to remove the drift errors accumulated on the flight. The outputs will reset in a step like manner. The aircraft must be stationary long enough for ANR to complete (7.5 to 15 minutes). If the aircraft is not stationary long enough for ANR to complete, the ADIRU will not apply any position corrections using GPS and will start over from the beginning when the aircraft is stationary again. If the aircraft continues to remain motionless, the ANR mode will apply small alignment resets once every minute to keep the system from drifting until it moves again. NOTE: ANR can cause movement of the MAP and various alerts as the IRSs align. To prevent an ANR, pilots should perform an initial full IRS alignment (i.e., MSU to OFF, then to NAV).

Question 28

What does the illumination of the ILS light on the IRS panel indicate?

Answer 28

Illumination of the ILS light indicates a failure of both ILS sensor units. Illumination of the ILS light during a MASTER CAUTION recall indicates a single ILS sensor unit has failed.

Question 29

How are outboard Display Unit failures automatically handled?

Answer 29

When an outboard DU failure is sensed, the displays will automatically reconfigure to ensure that each pilot has a PFD, and that an Engine Display is shown.