For domestic flights, it is generally recommended to arrive at the airport about 1.5 to 2 hours before your scheduled departure. This allows enough time for checking in luggage if needed, going through security, and reaching your gate without rushing. If you have only hand luggage and have checked in online, arriving about 1 hour before departure may be sufficient, provided there are no long queues or other delays. Airlines and airports may vary slightly in their recommendations, but the common advice for domestic flights is roughly 1.5 to 2 hours prior to departure. Larger and busier airports may require more time due to longer security and check-in lines. In summary:

• Domestic flights: Arrive 1.5 to 2 hours before departure.
• If only hand luggage and online check-in done: About 1 hour may suffice.
• For large or busy airports or checked luggage, plan for a full 2 hours.

This is a widely accepted guideline for airports in many countries, including Germany, the U.S., and Japan.