A320 Technical Interview Preparation: Airline Cadet to Junior First Officer
Airline recruiters are no longer satisfied with pilots reciting FCOM definitions by rote. They test whether you understand the operational consequences of system degradations. Master the high-yield A320 technical questions asked by major airlines.
Airbus A320 Fly-By-Wire Reversion Tree
1. Normal Law
Pitch: Load factor demand (+2.5g / -1.0g). Roll: Roll rate demand (max 15°/s). Protections: Pitch limit (+30°/-15°), Bank limit (67°), High speed, Alpha Floor & Angle of Attack protection. Auto-trim fully active.
2. Alternate Law
Pitch: Load factor demand preserved. Roll: Direct sidestick-to-roll surface relationship. Envelope protections downgraded to audio/visual warnings. Auto-trim remains operational.
3. Direct Law (Triggered when Gear Extended)
Deflection of elevators and ailerons proportional to sidestick deflection. Zero protections. Auto-trim is LOST—pilot must manually fly and trim using the pitch trim wheel (THS).
The Golden Rule of Airline Interviews: 'The Why Behind the What'
When interviewing for an Airbus A320 First Officer position at carriers like IndiGo, Air India, Emirates, or British Airways, the interview captain is evaluating far more than memorized numbers. They want to see if you understand the underlying architectural philosophy of fly-by-wire systems.
If an interviewer asks, 'What is the Power Transfer Unit?', reciting 'It transfers hydraulic power between Green and Yellow without fluid transfer' will only earn you a passing nod. But explaining *when* the PTU operates, *why* it is self-tested during second engine start, and *why* it is inhibited during single-engine taxi to prevent premature pump wear demonstrates the command maturity of a future captain.
Recruiter Secret
Assessors look for structural thinking: State the System Purpose → State Normal Operation → Detail the Degraded/Failure Mode → Explain Operational Consequences for the Flight Crew.
Flight Control Laws: Normal, Alternate, Direct & Mechanical Backup
The Airbus A320 flight control system commands control surfaces via flight control computers (ELACs, SECs, FACs). Understanding how the aircraft degrades through the control laws is the centerpiece of almost every technical interview.
| Flight Control Law | Pitch Handling | Roll Handling | Active Protections | Flight Deck Annunciation |
|---|---|---|---|---|
| Normal Law | Load Factor Demand (g-load) | Roll Rate Demand (max 15 deg/s) | Pitch, Bank, Load Factor, High Speed, Alpha Floor | Green '=' ticks on PFD attitude indicator |
| Alternate Law (with prot) | Load Factor Demand | Direct Roll (spoilers/ailerons) | Load Factor preserved; High/low speed stability warnings | Amber 'x' ticks; PFD displays 'ALTN LAW' |
| Alternate Law (without prot) | Load Factor Demand | Direct Roll | Only Load Factor protection (+2.5g/-1.0g) | Amber 'x' ticks; No stability warnings |
| Direct Law | Direct Stick-to-Elevator deflection | Direct Stick-to-Roll deflection | Zero protections; manual trim required | 'USE MAN PITCH TRIM' amber warning on PFD |
| Mechanical Backup | Mechanical cables to THS wheel | Mechanical cables to rudder pedals | None; solely aerodynamic forces | 'MAN PITCH TRIM ONLY' on PFD |
Key Requirements & Action Items:
- Why does Alternate Law revert to Direct Law when the landing gear is extended? Because without auto-trim and flare mode in Alternate Law, conventional landing flare feel requires a direct stick-to-surface relationship.
- What are the Normal Law pitch protection limits? +30 deg nose-up (decreasing to +25 deg at low speed) and -15 deg nose-down.
- What is the maximum bank angle in Normal Law? 67 deg. Beyond 33 deg, positive sidestick pressure is required to maintain bank angle; upon release, the aircraft automatically rolls back to 33 deg.
Hydraulics & The Power Transfer Unit (PTU): Critical Interview Scenarios
The A320 features three independent hydraulic systems operating at 3000 PSI: Green (Engine 1 driven), Blue (electric pump driven), and Yellow (Engine 2 driven + electric pump + hand pump for cargo doors).
The PTU is a bidirectional motor-pump that transfers power between Green and Yellow whenever the differential pressure exceeds 500 PSI. Crucially, the PTU is automatically inhibited under specific flight deck conditions to avoid ground hazards:
Key Requirements & Action Items:
- During first engine start (inhibited until both engines are running or electric pump is activated).
- When the parking brake is set and only one engine master switch is ON (prevents PTU running during single-engine taxi).
- When the PTU push-button switch on the overhead 40VU panel is selected OFF.
- When hydraulic reservoir fluid temperature or low level is detected on either Green or Yellow system.
Electrical Emergency Configuration & RAT Deployment
In the event of a total failure of AC BUS 1 and AC BUS 2 in flight, the Ram Air Turbine (RAT) deploys automatically from the belly fairing.
The RAT drives an emergency generator rated at 5 kVA, supplying essential AC and DC electrical networks (AC ESS BUS and DC ESS BUS via ESS TR). In this degraded electrical state, the flight controls downgrade immediately to Alternate Law, leaving the pilots with vital instruments, Captain's PFD, and basic communications.
Frequently Asked Questions
What happens to auto-trim in Direct Law?
Auto-trim is completely lost in Direct Law. The message 'USE MAN PITCH TRIM' appears on the PFD, requiring the flight crew to manually position the pitch trim wheel (THS).
How do you fly a crosswind landing on the A320?
Airbus recommends a crabbed approach into the wind on final. During the flare (at approximately 20 to 30 feet AGL), apply rudder to align the aircraft nose with the runway centerline ('decrab') while applying gentle opposite sidestick into the wind to keep wings level.
Can the PTU transfer hydraulic fluid between Green and Yellow systems?
No. The PTU is a mechanical shaft linking two separate hydraulic pumps. It transfers hydraulic pressure and mechanical energy, never hydraulic fluid.
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