If a TSA agent stops you, they must have a good reason to do so.

A TSA agent can’t just take a look at you and decide they have a bad feeling

A specific reason is necessary.

Thankfully – or perhaps not so thankfully in the interest of aviation safety – in 2015 a paper was leaked that stated the “92 signs to look out for” that TSA agents must follow.

So, here are the most common reasons why you might get flagged at the airport.

1. Your Behavior is Suspicious

TSA agents are trained to look at your behavior to see if you are suspicious in any way.

Your behavior, such as nervously looking around, even if you are overwhelmed for a good reason, such as you have a fear of flying, makes no difference.

A TSA agent may flag you for:

  • Looking nervous
  • Your eyes darting around
  • Yawning excessively
  • Coughing and clearing your throat excessively
  • Blinking excessively
  • Looking down at the ground often
  • A pale face due to having recently shaved
  • Rubbing or wringing your hands
  • Whistling
  • Exaggerated or excessive grooming gestures

2. You Are Traveling With Suspicious Items or Substances

Suspicious items or substances that could pose potential risks is one of the most common reasons why you can get flagged at the airport.

A black firearm handgun on a table

In particular:

  • Weapons and Sharp Objects: Firearms, knives, box cutters, and other sharp objects that can be used as weapons are not allowed in your carry-on.
  • Explosive and Incendiary Materials: Fireworks, flammable liquids, and explosive devices will all get you flagged.
  • Liquids and Gels: Liquids, gels, or aerosols that exceed 3.4oz/100ml are not allowed in your carry on.
  • Tools and Implements: Tools that can be used as a weapon, such as hammers, crowbars, and drills, are typically not allowed in carry-on luggage.
  • Chemicals and Toxins: Certain chemicals and toxic substances are prohibited due to their potential for harm or misuse.
  • Disguised Items: Objects designed to appear harmless but are concealing prohibited items, like hidden knives or weapons, are strictly forbidden.
  • Excessive Cash: If you are flying domestically within the USA, there is technically no limit to how much money you can bring on a plane, though excessive amounts can certainly arouse suspicion.

3. Your Travel History and Patterns

Your travel plans can make you seem more suspicious.

All of the following are part of the extensive list of 92 behaviors that TSA agents look for to deem if a passenger is high risk or not:

  • Pay for your ticket in cash
  • Book a one way ticket
  • Book your ticket at the last minute
  • Fly to or from a high-risk country
  • Have irregular recent travel patterns

4. Your ID is Inconsistent/Has Discrepancies

As your ID is used to verify your identity, there are certain discrepancies and inconsistencies that can get you flagged.

  • Name Changes: If you changed your name due to marriage, legal proceedings, or other reasons, there will be a mismatch between your current name and the name on your ID.
  • Typographical Errors: A simple typographical error, such as your name spelled wrong.
  • Expired or Invalid Identification: Carrying expired identification or documents that are no longer valid.
  • Different Spellings: Variations in spelling, use of initials, or abbreviation of names can all lead to inconsistencies.
  • Use of Nicknames: If a nickname is used on one document and the full name on another, it might cause confusion.

US passport resting on a global map

5. You Have Been Randomly Selected

Sometimes there is nothing about your behavior or actions that will cause you to get flagged. You have just been randomly selected for additional screening.

While it can be annoying, random screening adds an element of unpredictability to security checks, which makes it more challenging for potential threats to anticipate screening procedures.

How to Know If You’ve Been Flagged

You know if you’ve been flagged by a TSA agent in one of two ways:

1. You Boarding Pass Has “SSSS” Printed on It

SSSS stands for Secondary Security Screening Selection, which means that you will be required to undergo a more intensive screening process that may involve pat-downs.

Your carry-on luggage may also be inspected by hand, and a hand held metal detector will be used on your body.

2. You Are Flagged At Airport Security

When you begin the security screening process, you may be pulled aside and have to undergo additional screening.

Again, you and your personal belongings will have to undergo additional checks, that may involve a patdown.

TSA officers and passengers going through security screening procedures

How to Avoid Being Flagged

There are a few things you can before your flight to minimize the likelihood that you will get flagged at the airport.

1. Organize Your Luggage

Pack your belongings neatly to avoid clutter during X-ray screening, so the machines can identify your items more easily.

Place electronic devices, liquids, and items like keys in separate compartments for easier access.

2. Check Prohibited Items

  • Familiarize yourself with the list of prohibited items
  • Avoid carrying items that could raise security concerns, even if they are allowed, such as sharp objects and items that could be used as a weapon.

3. Accurate Documentation

  • Ensure all your identification documents are accurate and up to date.
  • Double-check your booking details to ensure they match the information on your ID.

a TSA agent confirming a passenger's identity

4. Dress Wisely

  • Opt for comfortable clothing that is easy to remove if required during security checks.
  • Avoid wearing clothing that may trigger an alarm, such as excessive metal elements or accessories that might trigger alarms.

What to Do If You’re Flagged

If a TSA agent flags you, and you are sure you haven’t done anything wrong, it’s likely that you will undergo a brief additional screening with minimal hassle and stress.

To ensure that things go as smoothly as possible:

1. Remain Calm

  • Stay composed if you are flagged during security checks.
  • Understand that you being flagged can occur due to a variety of reasons and are not necessarily indicative of wrongdoing.

2. Cooperate with Security Personnel

  • Follow instructions from security personnel calmly and promptly.
  • Answer questions truthfully and provide any necessary information.

A TSA officer inspecting a passenger's ID

3. Understand the Process

  • If asked, explain the contents of your luggage and any items that might appear suspicious on X-ray scans.
  • Be prepared for additional screening, which can include physical searches and more detailed inspections.

Ella Dunham, a Freelance Travel Journalist and Marketing Manager, boasts an impressive career spanning eight years in the travel and tourism sectors.

Honored as one of "30 Under 30" by TTG Media (the world’s very first weekly travel trade newspaper), a "Tour Operator Travel Guru" and "Legend Award" winner, Ella is also a Fellow of the Institute of Travel, a Member of the Association of Women Travel Executives, has completed over 250 travel modules, and hosts travel-focused segments on national radio shows where she provides insights on travel regulations and destinations.

Ella has visited over 40 countries (with 10 more planned this year).