A320 Autoflight Questions

On an autoland approach, with both autopilots on, which FMGC is master?

• FMGC 1
• FMGC 2
• Both
• None

Explanation: With two autopilots engaged, FMGC 1 is always the master (with a single AP engaged, whichever FMGC is paired with that AP is master).

Auto Flight - Description (Master FMGC Logic)

The ATT HDG and AIR DATA selectors on the switching panel in the NORM position indicate that:

• ADIRU 1 is supplying information to PFD 1 and ND 2, and ADIRU 2 is supplying power to PFD 2 and ND 1.
• ADIRU 1 is supplying information to PFD 1, ND 1 and the DDRMI; ADIRU 2 is supplying power to PFD 2 and ND 2.

Explanation: In NORM, ADIRU 1 supplies data to PFD 1, ND 1, and the DDRMI, while ADIRU 2 supplies PFD 2 and ND 2 — matching this option exactly (the FCOM also notes ADIRU 1 feeds VOR/DME, not mentioned in the option but not contradicted by it).

Navigation - ADIRS Controls & Indicators (Pedestal)

If both ELACs fail, what controls the elevator and stabilizer?

• FACs.
• SECs.
• Elevator and stabilizer revert to mechanical backup.
• Backup mode of ELAC's

Explanation: SECs (Spoiler Elevator Computers) provide standby elevator and stabilizer control — so if both ELACs fail, the SECs take over pitch control.

Flight Controls - General (Computers)

If the IR mode rotary selector is selected OFF:

• AD and IR information will be disconnected.
• AD information will be disconnected.
• IR information will be disconnected.
• The ADIRU is not energized: AD and IR information is lost.

Explanation: Setting the IR mode rotary selector to OFF de-energizes the ADIRU entirely, so neither ADR nor IR data is available.

Navigation - ADIRS Controls & Indicators

How many Air Data/Inertial Reference Units (ADIRU's) are installed?

• One
• Two
• Three
• Four

Explanation: There are three ADIRUs installed (each split into an ADR and an IR part), plus a switching facility that lets ADR 3 or IR 3 substitute for ADIRU 1 or 2.

Navigation - ADIRS Description

The IR ALIGN light is extinguished. What does this mean?

• Alignment has been completed.
• Air data output has been disconnected.
• The respective IR is operating normally.
• Alignment has been restarted.

Explanation: The ALIGN light goes out (extinguished) once alignment has been completed.

Navigation - ADIRS Controls & Indicators

What does the LOW ACCURACY message mean?

• FMGC 1 & 2 position difference exceeds limits.
• FMGC position & actual radio position difference exceeds limits.
• FMCG position & IR position difference exceeds limits.
• FMGC 2 position difference exceeds limits.

Explanation: LOW ACCURACY reflects the FMGS's Estimated Position Uncertainty (EPU) exceeding the Required Navigation Performance (RNP) — in the radio-updated navigation modes, EPU is computed from how well the FM position agrees with DME/VOR radio fixes, which is broadly what this option describes as an FMGC-vs-radio-position mismatch.

Auto Flight - Flight Management (Evaluation of Position Accuracy)

What causes a DU to display a black screen with a white diagonal line?

• The circuit breaker for that particular DU has popped.
• DMC failure.
• No power.
• New DMC installed, remove screen protection film.

Explanation: When a DMC fails, each of its associated Display Units shows a diagonal line — the black screen with a white diagonal line is the signature of a DMC failure.

Indicating/Recording Systems - Switching Panel / Reconfiguring the DMC