Airbus A320 Fuel System Operation: Transfer Sequence & Crossfeed Logic Explained

The Airbus A320’s fuel system is designed to do three things very well: store fuel safely, deliver it reliably to the engines and APU, and keep the aircraft’s balance within limits with minimal pilot workload.

This article walks through the practical operation of the system—tank layout, normal engine feed, automatic fuel transfer, and crossfeed usage—then ties those concepts to the indications you see on ECAM and standard operating techniques.

References to Airbus source material are included parenthetically where helpful (e.g., ATA 28 in the FCOM/AFM; FCTM Procedures).

A320 System Overview and Tank Layout

The A320 family uses integral fuel tanks in the wings and center fuselage. In the most common configuration, fuel is stored in the wings (a wing inner tank and an outer tank on each side) and in a center tank—that is, a wing and a center arrangement typical of the A320/A321 family. Each wing also has a vent/surge tank connected via a spill pipe and fuel vent to manage expansion and overflow during refueling. These tanks prevent overfill help avoid fuel spillage on the ramp.

Fuel quantity indication uses capacitive probes and compensators to compute fuel level, fuel volume and the amount of fuel in each tank. The totals and per-tank values appear on the ECAM FUEL page; this is your primary reference to check the fuel quantity before flight and monitor fuel in each tank in cruise. While the article focuses on the A320, note that the A321 follows the same logic with configuration differences in tank capacity and some options.

Controls and Indications

From a pilot’s perspective, everything important lives on the overhead FUEL control panel in the cockpit and the ECAM FUEL page. On the overhead you’ll find wing tank pumps, main fuel pumps for the center tank (CENTER L/R), the X FEED pushbutton (crossfeed valve), and refuel/defuel selectors for ground use at the refueling points. Associated fuel valves (including engine LP isolation valves and transfer valves) and, on some configurations, a jet pump for transfer, work under system logic to allow fuel movement without constant crew input. Suction capability through suction valves provides backup feed paths in certain conditions.

On ECAM, you’ll see pump/valve status, per-tank quantities, and alerts tied to system protections. Labels such as TK PUMP 1 or CTR TK PUMPS OFF cue you to what the logic is doing. The system is part of ATA 28 Fuel; system includes balanced feed manifolds, tank sensors, transfer valves, and protections that system to ensure stable fuel to the engines and the auxiliary power unit.

Normal Engine Feed Sequence Operation (What the System Tries to Do by Itself)

In normal operations the A320 follows a predictable feeding order to ensure structural and CG considerations are respected while keeping engine supply stable:

1. Center tank first when permitted. When usable fuel from the center tank is available and logic criteria are met, the system prioritizes fuel from the center. Dedicated center pumps pressurize the manifold so that center fuel is used before inner wing fuel (typical operation when the center tank has sufficient quantity; center tank pump automatic cut-off occurs at low quantity, e.g. ≈200 kg remaining, to avoid dry running). You may see an ECAM memo inhibiting center feed at specific phases to prevent fuel pressure transients (center feed is inhibited for takeoff/initial climb and re-enabled automatically once the logic criteria are satisfied).
2. Then inner wing tanks. After center-tank depletion or inhibition, the engines receive fuel from the tank (left/right inner wing) via their main fuel pumps—i.e., wing tanks to the engines is the default path for most of the flight (each inner tank carries several tonnes of usable fuel; automatic outer-to-inner transfer typically begins when inner quantity decreases to about 750 kg ±150 kg).
3. Outer-to-inner top-up. Outer tanks are not direct feed sources. When inner tank quantity decreases to a threshold, transfer valves open to allow fuel to gravity-transfer from outer to inner, maintaining wing bending relief and center-of-gravity control (outer tank content is on the order of ≈700 kg and is transferred to the inner tank; valves close again once the inner tank rises above the threshold).

Two subtleties matter to pilots:

• Center tank inhibition at takeoff/initial climb. To protect engine feed pressure and lateral balance at a critical phase, center feeding is inhibited. The system re-enables it automatically when criteria are satisfied; you’ll see associated ECAM status changes (expect the ECAM center-tank pump annunciation to remain inhibited until the phase-of-flight logic clears).
• Automatic pump shutoff. When a center pump runs dry, it shuts off automatically and the status is shown on ECAM, preventing damage and nuisance messages (center pump auto-off at low quantity—commonly cited around ≈200 kg—protects the pump).

Typical Fuel Quantity References (A320 family, ATA 28; verify per aircraft MSN)

Notes: Quantities above reflect typical A320 family values and are provided for explanatory context. Always use your aircraft’s Airbus FCOM/AFM (ATA 28) and company procedures for exact thresholds and limitations.

Crossfeed Valve: Purpose and Practical Use

The crossfeed valve connects the left and right manifolds. In balanced operations it remains closed. You open it deliberately for specific scenarios:

• Feeding both engines from one side to manage a suspected leak or pump issue. With crossfeed open and appropriate pump selection, you can supply both engines from the heavy side while isolating the other.
• Correcting a small imbalance. A short, timed crossfeed session—favoring the heavy side pumps—can bring the wings back within limits. Many training programs use practical targets like approximately 500 kg of fuel difference as a cue to act and 500 kg as a typical “within limits” goal after correction; always follow the AFM/QRH values for your tail.

Use a disciplined call-out: open, time, monitor, close. Extended crossfeed without monitoring risks creating the very imbalance you were trying to fix.

ECAM: What You See When the Logic Works (and When It Doesn’t)

The ECAM FUEL page and E/WD alerts provide the “glass” view of the logic. Typical items you’ll observe:

• CTR TK FEED / CTR TK PUMPS OFF around takeoff/climb, reflecting the inhibition logic.
• PUMP status tied to pushbutton states and automatic shutoff protections.
• Valve positions (X FEED and transfer) depicted with open/closed symbology.
• Low level and FUEL IMBALANCE cautions if thresholds are exceeded.

Operating Techniques by Flight Phase

Preflight and Refueling

At the gate, confirm fuel is available in the required tanks and that the planned tank usage supports CG. During refueling, monitor the amount of fuel loaded and watch the vent surge tank for any overflow behavior if temperatures rise quickly. Verify totals on ECAM against the release (check the fuel quantity) and ensure all wing tank pumps and center pumps are set ON unless MEL dictates otherwise. The A320 fuel management design uses logic and protections to fuel efficiently with minimal pilot workload.

Engine Start and Taxi

With pumps ON and crossfeed CLOSED, each engine should see stable fuel pressure on ECAM. The APU, if running, will normally draw from the left side. Any FUEL LO PR-type message prompts a quick scan: fuel valves, pump state, then crossfeed if needed to restore pressure while troubleshooting.

Takeoff and Initial Climb

Expect inner tanks to supply the engines during the inhibit window. Once inhibit conditions clear, fuel transfer logic resumes normal priorities, including fuel from the center tank when permitted. If logic seems out of step (e.g., center fuel remains but pumps show off with no inhibit reason), follow the ECAM/QRH path rather than forcing configuration.

Cruise

In cruise, the system mostly looks after itself. Center fuel (if any) is used first; then inner tanks; outer-to-inner transfer opens automatically to allow fuel movement when thresholds are met. Monitor trends: planned burn, balance, and pump/valve states. If you’re managing a small imbalance, a short, timed crossfeed is usually enough; avoid over-correction.

Descent and Approach

By approach you are almost always on inner wing tanks. Aim for a tidy lateral balance and stable CG. If a balancing action is required, complete it early and re-establish the normal configuration well before landing. As a rough training figure some operators use approximately 750 kg as a practical pre-landing target to keep any remaining difference small; always respect the specific AFM/QRH limits for your aircraft.

Component and Function Summary (ATA 28)

Abnormal Scenarios Worth Practicing

Fuel Imbalance

When ECAM calls an imbalance, verify cause before acting. If no leak is indicated, feed both engines from the heavy side for a short period (crossfeed OPEN, light-side pumps OFF), then close crossfeed and re-check. Record start/stop times to avoid overshooting. Many training programs treat approximately 500 kg of fuel as a practical imbalance cue; always apply your AFM/QRH values.

Suspected Fuel Leak

Focus on isolation. Use trends in quantity, engine parameters and alerts to identify the likely side, close the appropriate fuel valves, and use crossfeed to keep both engines supplied from the unaffected side. Work the QRH methodically.

Center Tank Anomalies

If a pump won’t stay on with fuel indicated, suspect sensor/logic issues and follow ECAM/QRH. Avoid ad-hoc workarounds that defeat inhibit protections. If the system needs attention after maintenance, confirm status of related fuel components on the overhead and ECAM before dispatch.

Readability Cues on ECAM

Think of the FUEL page as a storyboard: highlighted pumps/valves are the actors; amber labels demand attention; the quantity blocks tell you if transfers are happening. If a message like TK PUMP 1 or a valve disagrees with the expected phase, pause and reconcile before changing configuration.

Answers to Common Questions

What are the core parts of the A320 fuel system?

Center, inner and outer fuel tanks; vent/surge tanks; center and wing tank pumps; transfer and isolation fuel valves; the crossfeed valve; sensors for fuel quantity indication; and the ECAM/overhead control panel. Together, the A320 fuel system is designed to protect feed pressure, balance and CG.

How many fuel pumps does the A320 use?

Each inner wing tank has its pump set; the center tank has its own main fuel pumps (L/R). Some configurations include a transfer jet pump. Exact counts and labels can vary by engine and options; refer to your aircraft’s FCOM/AFM.

Which fuel is used on the A320?

Certified aviation turbine fuels per AFM limitations (e.g., Jet A/Jet A-1, depending on approvals). Always use the AFM/AMM for specifics.

How does fuel move from the outer to the inner wing tanks?

Via automatic transfer valves that open at defined thresholds, allow fuel to gravity-flow inward. The engines then feed from the inner tanks.

Why is center tank feeding restricted at takeoff?

To protect engine feed pressure and lateral balance at a critical phase. The logic inhibits center feed and then restores it when criteria are met.

Good Habits That Make Fuel Easy

• Keep pumps ON, crossfeed CLOSED unless a checklist directs otherwise.
• Monitor trends (burn and balance) rather than single snapshots; verify fuel is stored where you expect and fuel is available to the current feed path.
• Use crossfeed deliberately—brief, announced, monitored, then closed.
• Respect inhibit logic; don’t out-smart protections close to the ground.
• If maintenance touched ATA 28, verify expected tank usage and panel states on power-up.

Key Takeaways

The A320 fuel system is largely self-managing: center first when permitted, then inner tanks; outer tanks quietly replenish inner tanks; the crossfeed is there for balancing and abnormals. ECAM and the overhead panel give you the full picture to manage the system efficiently and safely from start to shutdown.

Editor’s Notes on Sources

Content aligned with Airbus primary documentation for the A318/A319/A320/A321 fleet (ATA 28 Fuel): Flight Crew Operating Manual (DSC-28 Fuel; DSC-31 Indications), Airplane Flight Manual (LIM-28/ABN-28), and Flight Crew Techniques Manual (SOP and abnormal handling). Operator policies and MEL always take precedence.

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