New Study Challenges the Conventional Wisdom of Arriving Two Hours Early for Flights

A new National Bureau of Economic Research (NBER) study shows that the conventional wisdom about when to arrive at the airport could be costing you more time than it saves in missed flights.

The research, conducted by Joshua S. Gans at the University of Toronto’s Rotman School of Management, analyzed the best airport arrival timing and found that the best time to get to the airport isn’t a set time like two hours, but depends on how often flights depart, how much you’d lose if you missed one, and whether earlier flights are available. In fact, under certain conditions, the option to hop on an earlier flight can increase your waiting time at the airport, even as it reduces your risk of missing your original departure.

The Math Behind Airport Anxiety

While United Airlines (UAL) and other airlines still tell passengers that the Transportation Security Administration (TSA) recommends arriving at airports two hours before domestic flights and three hours before international departures, the TSA itself has shifted toward a more vague recommendation to “allow time for parking/shuttle transportation, airline check-in, obtaining a boarding pass and going through the security screening process, which includes screening of your carry-on bag.”

TSA wait times vary dramatically across airports. Recent data show average TSA wait times ranging from just 9.1 minutes at Salt Lake City International Airport to over 20 minutes at major hubs like Honolulu’s Daniel K. Inouye International Airport.

According to Department of Homeland Security data, TSA screened 904 million passengers in 2024, a 5% increase from 2023. Despite this growth, the agency maintains that 99% of TSA PreCheck passengers wait 10 minutes or less, though independent surveys suggest the reality is closer to 36 minutes on average for PreCheck members.

The NBER study reveals how these differences can help you determine when to arrive for your flight. Gans modeled the trade-off between waiting costs (your time) and missing flight penalties (rebooking fees, lost time waiting for the next flight). His model suggests something that few travelers are willing to chance: you should occasionally miss flights since that means you’re shaving off time on other flights.

When Earlier Flights Work Against You

Perhaps the study’s most counterintuitive finding involves what Gans calls the “earlier flight paradox.” In one of his examples, a traveler faces a moderate $35 penalty for missing their flight, but increases their average waiting time from 10.21 minutes to 13.54 minutes when an earlier flight becomes available.

This happens because the earlier flight option creates what economists call a “recourse opportunity”—travelers rationally adjust their departure time to capture the value of potentially catching an earlier flight, even though this means arriving at the airport sooner and waiting around longer, on average.

This becomes more pronounced for business travelers and those with moderate costs for missing a flight. For high-penalty scenarios (such as a significant rebooking fee), earlier flights deliver substantial benefits, reducing waiting time by almost half (44.4%). But when the penalties are less severe, the benefit of doing so drops.

The Half-Headway Rule: Why Frequent Flights Have Limits

The study introduces what Gans calls the “half-headway rule”—a built-in limit on how much planning can cut your wait. Simply put: when flights run on a regular schedule, your average wait will always be about half the gap between flights, no matter how carefully you time your arrival.

That means if flights leave every hour, you can expect to wait about 30 minutes on average. If they leave every two hours, the wait averages closer to an hour. This helps explain the intuition that you’re better off when there are more frequent flights between your airport and the destination. More departures don’t just give you flexibility—they mathematically cap your airport wait time. But even the most meticulous planner can’t beat the half-headway ceiling.

The Bottom Line

A new NBER study sheds light on a classic travel debate: how early do you need to arrive at the airport? You can check historical wait times and the busiest parts of the day for your specific airport by checking with the TSA. However, the “right” arrival time also depends on how much it would cost you to miss a flight and whether earlier flights are an option. Ultimately, though, procrastinators can be heartened: getting to the airport super early is often a waste of time.