How does the A320 outflow valve work in a simulator?

The Airbus A320 outflow valve controls cabin pressure by varying how quickly conditioned air escapes; it does not pump air into the cabin. In Aviation & Real-World Flying simulators, automatic cabin-pressure controllers normally move it through climb, cruise and descent, while the ECAM PRESS page shows valve position and the resulting pressure.

What does an outflow valve in an aircraft actually control?

The A320 outflow valve meters air leaving the pressurised fuselage while the air-conditioning packs provide a continuous inflow. Closing the valve retains more air and increases pressure; opening it releases air, reduces differential pressure and allows cabin altitude to rise.

An outflow valve in an aircraft is therefore a controlled outlet, not a compressor or air pump. In any pressurised plane, cabin pressure depends on both sides of the equation: conditioned-air inflow and controlled outflow. Our explanation of how airflow, cabin altitude and differential pressure interact covers that underlying relationship. The standard spelling is outflow valve, although some simulator material uses out flow valve for the same component.

The A320 has one main electrically operated outflow valve. Two automatic motors are associated with the two cabin-pressure controllers, while a separate motor provides manual control. One controller normally operates the system, the other is available as a backup, and their duties alternate between flights.

Independent safety valves protect the fuselage against excessive positive or negative differential pressure. They are protective devices, not the normal method of regulating A320 cabin pressure. Selecting DITCHING also commands the outflow valve closed as part of sealing openings below the flotation line.

How does the cabin pressure controller on an A320 use the valve?

In AUTO, the active A320 cabin pressure controller schedules cabin altitude for each flight phase and positions the outflow valve to achieve that schedule.

The controllers use aircraft altitude, flight phase, planned cruise level and landing elevation. With landing elevation in AUTO, a detailed simulation normally obtains the destination elevation from the programmed flight plan. A missing destination, incorrect arrival airport or unsuitable manual landing-elevation entry can cause strange descent behaviour even when the valve itself is serviceable.

A valve shown near closed during climb is not automatically stuck. The meaningful evidence is the combination of valve position, cabin altitude, cabin vertical speed and differential pressure over time.

How is the A320 outflow valve modelled in a simulator?

Outflow-valve fidelity depends mainly on the aircraft add-on rather than the simulator platform.

• Systems-level aircraft: The two controllers, automatic and manual motors, electrical supply, pack flow, doors, landing-elevation logic, failures and ECAM indications may all interact.
• Simplified aircraft: Cabin altitude may use generic simulator pressure variables while some overhead controls and ECAM indications remain decorative.
• Visual-only implementation: The external valve animation may respond to airspeed or ground state without affecting cabin pressure.

Older FSX packages illustrate this distinction clearly. One Air Macau A320 implementation documents ground-valve opening below 30 knots, while a TAM package describes XML-driven pressurisation and outflow-valve animation. These features provide useful visual feedback, but they do not by themselves prove that dual-controller logic or realistic pressure physics are modelled.

How should you operate and monitor A320 cabin pressure?

Normal simulator operation is to establish pack airflow, seal the aircraft, leave pressure control in AUTO and monitor the result rather than positioning the valve directly.

1. Establish an air supply. Supply the packs from an appropriate engine or APU bleed source. A closed outflow valve cannot pressurise a cabin with no incoming air.
2. Close the aircraft. Check passenger doors, cargo doors and any modelled cockpit windows. A simulated open door can act as a large leak.
3. Programme the flight data. Enter the cruise level and destination. Leave landing elevation in AUTO unless the aircraft simulation or a specific failure procedure requires a manual value.
4. Leave MODE SEL in AUTO. Manual control is intended for controller failures and training, not routine adjustment.
5. Monitor the ECAM PRESS page. Read cabin altitude, cabin vertical speed, differential pressure and outflow-valve position together.
6. Confirm depressurisation after landing. Differential pressure should return towards zero and the valve should eventually show open. It need not move fully open at the instant of touchdown.

How does manual outflow-valve control work?

Manual mode lets the crew drive the valve using the spring-loaded MAN V/S CTL switch. The labels describe the desired direction of cabin altitude: UP opens the valve and raises cabin altitude, while DN closes it and lowers cabin altitude or slows its rise.

Use short inputs and watch the cabin vertical-speed trend rather than holding the switch continuously. Valve movement and pressure response are not instantaneous, so prolonged input can cause a large pressure change. Some simplified A320 simulations animate the switch but do not model the separate manual motor.

ECAM outflow valve stuck: what it means in an A320 simulator

An ECAM outflow valve stuck indication means the displayed valve position remains open, closed or unchanged when the flight phase and pressure trend suggest that it should move.

How can you recognise a genuinely stuck indication?

A fully open valve while parked is normal after the cabin has depressurised. Some add-ons also keep the external animation open during taxi until their ground-speed logic triggers pre-pressurisation.

• Apparently stuck open: During climb, the ECAM position remains at the open end while cabin altitude rises rapidly, differential pressure stays low and the cabin begins to follow aircraft altitude.
• Apparently stuck closed: The indication remains closed during descent or after landing, cabin altitude does not approach airport elevation, or positive differential pressure does not reduce. A near-closed indication during climb or cruise can still be normal.
• Unresponsive indication: The position pointer, symbol or percentage never changes through several flight phases or after a brief manual command. If pressure values respond normally, the display or animation may be cosmetic rather than the valve being physically stuck.

Do not diagnose the valve from position alone. A controller can command it closed because pack airflow is weak, yet the cabin still fails to pressurise because there is not enough incoming air.

Safe simulator troubleshooting sequence

Use this order to separate a genuine modelled failure from incorrect configuration or incomplete add-on logic.

1. Return to normal simulation speed. Stop time acceleration, slew and state changes. Pressure controllers in some aircraft become unstable or skip logic when the simulation is accelerated.
2. Read the whole PRESS page. Note the flight phase, cabin altitude, cabin vertical speed, differential pressure and valve position. An open valve and zero differential pressure are normal on the ground.
3. Confirm automatic configuration. Put MODE SEL in AUTO, release the MAN V/S CTL switch and check that DITCHING is not selected. Verify that the aircraft has the electrical power needed by its controllers and valve motors.
4. Check packs and bleed supply. Confirm that at least one valid pneumatic source is feeding the packs and that pack flow is indicated. Check engine bleed, APU bleed, crossbleed and any modelled pressure-regulating valve status.
5. Check every door and opening. Close passenger and cargo doors and allow the aircraft state to update. A door animation that looks closed may still have an open system variable in some add-ons.
6. Validate flight-plan data. Confirm the destination, cruise altitude and landing elevation. If AUTO landing elevation is unreliable in that aircraft, enter the airport elevation only as its documentation directs.
7. Reinitialise a bad aircraft state. Directly loading an aircraft at cruise altitude can leave pressurisation variables in a ground or undefined state. Reload from a supported ground state, then establish power, bleed air and packs in the normal sequence.
8. Test MAN only in a controlled simulator setup. Preferably on the ground, select manual mode and make brief UP and DN inputs while watching the indication. If MAN moves the valve but AUTO does not, suspect controller logic, flight data or an automatic-system failure.
9. Inspect add-on-specific failures. Check the aircraft's own failure or maintenance system for controller, valve actuator, pneumatic or electrical faults. If the add-on has no pressurisation failures and the display never responds, the control may simply be unmodelled.

This is simulator fault isolation, not a substitute for an approved real-aircraft abnormal procedure. When an add-on provides its own ECAM actions or checklist, follow those actions rather than improvising prolonged manual valve movement at altitude.

What is the A320 PRSOV?

The pressure-regulating shut-off valve, often abbreviated PRSOV, belongs to the pneumatic bleed-air supply path; it is not the cabin outflow valve.

A PRSOV regulates bleed pressure and can shut off an engine's contribution to the pneumatic manifold. A320 terminology varies between manuals and simulator add-ons, so the equivalent component may be labelled as an engine bleed valve or pressure-regulating valve. The pack flow-control valves are separate components farther along the supply path.

If a PRSOV is closed because of a command, protection logic or simulated failure, the affected engine may provide no usable air to the packs. Another engine or the APU may still supply them through the appropriate crossbleed configuration. With no pack airflow from any source, the cabin cannot pressurise even if the outflow valve closes and operates correctly.

For PRSOV A320 troubleshooting, check the BLEED indications and pack flow before blaming the outflow valve. No pack flow, rising cabin altitude and differential pressure near zero point first towards pneumatic supply, pack control or a large leak.

A320 cabin pressure: ECAM-led troubleshooting table

The quickest diagnosis comes from matching the ECAM pressure trend to valve and pack behaviour rather than treating any single indication as proof of failure.

Across A320 add-ons, the mistake we see most often is trying to cure missing pack or bleed airflow by closing the outflow valve manually. The valve can retain air that reaches the cabin, but it cannot create airflow, close a simulated door or repair an unmodelled pressurisation system.