If there's a mistake in your name, nationality, date of birth, or passport/ID details, the carrier might not allow you to board. You might also face difficulties getting through immigration.

Putting the wrong passport number on a flight booking is a serious error that must be corrected before travel. Here’s what happens and what you should do:

Immediate Consequences & Risks:

1. Check-In Denial (Most Likely Outcome): At online check-in or at the airport, the passport number you provided will be checked against the actual passport. A mismatch will flag the system. You will likely be blocked from checking in online and will have to go to the airline counter for manual verification and correction.

2. Significant Delays at the Airport: You cannot simply breeze through. An agent must manually correct the passport details in the booking system, which can take time, especially during peak hours.

3. Security & Immigration Issues: Airlines are required to send accurate API (Advanced Passenger Information) to immigration authorities of the destination country before departure. A mismatch can cause alerts, leading to additional questioning by immigration officers or even denial of boarding if the error can’t be resolved in time.

4. Possible Fees: Some airlines may charge a fee to correct passport details, especially if done at the airport. This is less common if you correct it yourself in advance.

5. Risk of Being Denied Boarding: In the worst-case scenario, if the error is discovered too late (e.g., at the gate) and there isn’t enough time to verify and correct it, the airline has the right to deny you boarding. This is because they face fines for submitting incorrect passenger data.

What You MUST Do:

1. Don’t Panic, But Act Immediately.