Starting up an Airbus A320 involves a sequence of checks and procedures to ensure the aircraft is ready for operation. Below is an outline of the general startup process, but always refer to your airline's Standard Operating Procedures (SOP) and the Aircraft Operating Manual (AOM) for precise details.

1. Pre-Startup Preparations

• Exterior Walkaround: Confirm the aircraft is in good condition with no visible issues.

• Power-Up: Connect external power or use the APU for electrical power.

2. Cockpit Preparation

• Battery Master Switches: Turn on BAT 1 and BAT 2.

• External Power: If available, turn on EXT PWR.

• APU Start (if needed):

  • Press the APU MASTER SW.

  • Press the APU START button. Wait for the "AVAIL" light.

• Emergency Equipment: Confirm fire extinguisher, crash axe, oxygen masks, and life vests are in place.

3. Preliminary Cockpit Checks

• Aircraft Documents: Verify required documents are onboard.

• FMS Initialization: Program the flight plan, departure/arrival, and performance data.

• IRS Alignment: Set the IRS mode selectors to NAV and confirm alignment status on the MCDU.

• Fuel Quantity: Check against the operational flight plan.

• Lights and Signs:

  • Turn on NAV & LOGO lights.

  • Seatbelt and no smoking signs ON.

4. Before Engine Start

• APU Bleed: Turn ON if APU is being used for engine start.

• Beacon Light: Turn ON.

• Parking Brake: Ensure it is set.

• Pushback Clearance: Obtain clearance if required.

5. Engine Start Procedure

1. Engine Mode Selector: Set to IGN/START.

2. Start Engine 2:

   • Move ENG 2 master switch to ON.

   • Monitor N2 and ensure stable idle (~20%).

3. Start Engine 1:

   • Move ENG 1 master switch to ON.

   • Monitor parameters for stable idle.

4. Check Engine Instruments: Ensure all parameters are within limits.

6. After Engine Start

• Engine Mode Selector: Return to NORM.

• APU: Turn OFF if no longer needed.

• Hydraulic Systems: Verify pressure.

• Flight Controls: Perform control surface checks.

• ECAM: Check for warnings or errors.

7. Taxi Preparation

• Ground Clearance: Confirm taxi clearance.

• Taxi Lights: Turn ON.

• Parking Brake: Release.

• Throttle: Apply as needed for taxi.

This sequence provides a general overview. The specifics may vary depending on the airline and aircraft configuration. Always prioritize safety and compliance with regulatory procedures.