A viral TikTok trend has emerged called “airport theory” that advises arriving at the airport just 15 minutes prior to departure – the claim is that you can still make it through security and board before the doors close.

Of course most airlines will give away your seat if someone is standing by for it 15 minutes prior to departure, and close the doors 10 minutes out. So 15 minutes is a bit of an exaggeration. But the general sentiment is right, but the advice – especially for people likely to receive it on TikTok – is not.

@itslexismith

testing airport theory at LAX

♬ original sound – Lexi Smith

However, not all attempts are successful—there are clear instances where travelers missed their flights. Reportedly the TikTok trend has led to a dramatic spike in online searches for missed flights.

@jenny_kurtzz i would not recommend ✈️ #airporttheory #airport #flying #fyp #lifehack #tipsandtricks ♬ son original – tswiftmusic

I frequently say that there’s no reason for many people to show up at the airport 2.5 hours prior to a domestic flight. Airlines and airports give very conservative guidance because (1) they don’t want to be blamed by outlier cases where someone shows up closer to departure and misses their flight, and (2) they benefit from people who are there earlier, ready to travel, and spending money at the retail shops while they wait.

However, the amount of time you should arrive prior to departure depends on:

• Checked bags. That adds time to your airport journey. How much time depends on whether you’re flying coach or in a premium cabin, whether you have status with the airline, and whether there are other options like curbside check-in that you could pay for in a pinch.

• Priority security. If you have PreCheck or CLEAR or both – and these are going to be available to you – there’s less risk that security will take inordinately long to get through. The biggest risk factor in getting through the airport is the security line. There may be almost no line at all, or it may be an hour long, and while there are ways to make educated guesses about which to expect the truth is that it simply varies. Having options to use different queues helps reduce (but not eliminate) this risk.

• Whether you have special needs and that’s not just a need for wheelchair service. It includes the need for frequent bathroom stops, or the need to shop for snacks and other items to prepare for a trip. If you must stop to buy a toy to keep a child occupied during the flight, that’s a special need too. So is having time to run a toddler around and let them get out excess energy before they’re forced to stay still for the flight.

• Which airport you’re flying from since some major airports are easy to get through while others like Miami, Austin, Denver, and Atlanta can be a disaster.

• How bad it would be to miss the flight? There are some meetings that you absolutely must get to, and some personal engagements too. You don’t want to miss your annual board meeting or your wedding! But maybe if you missed the flight to see the in-laws for Thanksgiving that’s actually ok? You made the effort and were hosed by the airline – and dodge the bullet of excruciating conversation over turkey!

If you absolutely must be somewhere, travel early and with backup options to get where you’re going in time.

However, for many trips, take ordinary care. If you have PreCheck and CLEAR and you aren’t checking bags, walking into Washington’s National airport while your plane begins boarding is actually usually ok! You might not get overhead bin space but you’ll probably have no difficulty making your flight – as long as you don’t need to stop at Starbucks or for a long potty break along the way (they have lavatories on planes).

If I want to be leisurely about it, I’ll leave home around 90 minutes before my flight. That way I’m comfortably walking into the airport an hour out, which is great even if I’m checking bags (at elite bag check, or pay for curbside – American outsourced its curbside check-in and there’s now a per bag fee which of course trades off with tips for staff). Austin airport’s security situation has gotten quite bad, with only a single checkpoint offering TSA Pre. Nonetheless, that’s plenty of time to clear security in the worst case and make it to the gate prior to boarding commencement. But I could easily shave that down 20 minutes, and my worst case scenario becomes having to gate check my bag.

It all comes down to knowing how long the different pieces of the journey are likely to take, how much buffer your planning gives you, and just how bad it would be if you suffer a two standard deviation event along the way.