TSA security checkpoints at Miami International Airport (MIA) generally open between 4:00 AM and 4:30 AM, though the exact timing can vary slightly by terminal. For instance, Checkpoint E (Central Terminal) frequently begins operations as early as 4:00 AM to accommodate early morning international and domestic departures. The North Terminal (Concourse D), which handles a large volume of American Airlines traffic, also typically opens its main checkpoints by 4:30 AM. To avoid long morning queues, passengers are encouraged to use the "MIA Reserve" system, which allows for scheduled security appointments. It is worth noting that while checkpoints are open, specialized lanes like TSA PreCheck or CLEAR might have slightly different start times depending on staffing levels. Travelers are advised to arrive at least three hours before international flights, even with early morning openings, to account for potential bag drop or immigration processing delays.