How Airport Security Works

Airport security begins long before a passenger reaches the checkpoint.

The visible part of the system includes:

• Identity verification
• Carry-on screening
• Passenger screening
• Checked-baggage screening

But behind that are other layers:

• Passenger vetting
• Airport access control
• Employee authorization
• Restricted security areas
• Cargo security
• Perimeter protection
• Law enforcement
• Airline security programs
• Onboard security measures
• Incident response

No single scanner or checkpoint procedure is expected to stop every threat.

Modern aviation security is designed around layers.

This guide focuses primarily on the U.S. system built around the Transportation Security Administration, while explaining where international systems differ.

For the broader physical and operational airport system, see Airport Operations 101.

Security Versus Safety#

Aviation safety primarily deals with preventing accidental harm.

Examples include:

• Aircraft maintenance
• Runway incursions
• Weather
• Fire protection
• Operational errors

Aviation security is primarily concerned with protecting civil aviation from intentional unlawful acts.

Examples include:

• Weapons
• Explosives
• Unauthorized access
• Sabotage
• Hijacking
• Other deliberate threats

The two overlap operationally, but they are not the same discipline.

Airport Security Is Not Just TSA#

In the United States, TSA is the federal agency most passengers associate with aviation security.

But TSA is only one part of the system.

Responsibilities are shared among organizations such as:

• TSA
• Airport operators
• Airlines
• Contract screening companies at participating airports
• Local and airport law enforcement
• Federal law-enforcement agencies
• Cargo and ground-service organizations

The airport operator itself has extensive security responsibilities under federal regulation.

TSA#

TSA's aviation-security responsibilities include areas such as:

• Passenger screening standards
• Baggage screening
• Security oversight
• Passenger vetting
• Transportation-security regulation
• Inspection and compliance
• Federal Air Marshal operations
• Security technology

At most U.S. commercial-airport checkpoints, screening is performed by TSA personnel.

But not all of them.

Private Screeners Can Operate TSA Checkpoints#

Under TSA's Screening Partnership Program, participating airports can use qualified private screening companies.

Those companies still:

• Work under TSA oversight
• Follow TSA screening procedures
• Use approved screening standards

So: "Every airport checkpoint is staffed directly by TSA employees"

is not quite correct.

TSA retains federal oversight and ultimate responsibility for the screening program.

The Airport Operator Has Its Own Security Program#

U.S. airports subject to 49 CFR Part 1542 must maintain a TSA-approved airport security program.

That program covers high-level areas such as:

• Restricted-area boundaries
• Access control
• Personnel identification
• Employee authorization
• Law-enforcement support
• Security training
• Incident management

The details of individual airport security programs can contain Sensitive Security Information and are not public operational manuals.

For understanding airport security, the important point is:

the airport itself is an active security organization, not merely the building where TSA operates.

Airlines Have Security Responsibilities Too#

Aircraft operators also operate under federal security requirements.

Airline responsibilities can include areas such as:

• Passenger information transmission
• Aircraft security
• Baggage processes
• Cargo security
• Access to aircraft
• Coordination with TSA and airport operators

Responsibility is therefore distributed.

Security Is Different From Customs and Immigration#

Another common misconception is that:

airport security = border control.

They are different systems.

Security#

Asks questions such as:

Is the person and their property cleared to enter the protected aviation environment?

Customs and immigration#

Deal with questions such as:

May this person or these goods legally enter or leave the country?

In the United States, Customs and Border Protection handles border-entry functions.

TSA screening is not immigration inspection.

Security Starts Before the Checkpoint#

For passengers on covered flights, security screening begins conceptually before they reach the terminal.

Passenger information is processed through TSA's Secure Flight program.

Secure Flight performs passenger prescreening and watch-list matching before the physical checkpoint.

That is different from the TSA officer checking your ID.

Watch-List Matching Versus Identity Verification#

These are separate functions.

Passenger vetting#

Secure Flight evaluates passenger information against applicable government screening information.

Identity verification#

At the airport, TSA verifies that the person presenting themselves for travel matches an acceptable identity credential and an eligible reservation/screening status.

Physical screening#

The passenger and accessible property are then screened for prohibited security threats.

So the sequence is roughly:

vetting → identity → physical screening

not one single "ID check."

REAL ID#

As of May 7, 2025, TSA began enforcement of REAL ID requirements for state-issued driver's licenses and identification cards used at U.S. airport security checkpoints.

For an adult traveler using a state-issued driver's license or ID:

• The credential generally needs to be REAL ID compliant.

But REAL ID is not the only acceptable identification.

Other acceptable forms can include documents such as:

• Passports
• Passport cards
• Certain federal credentials
• Other TSA-accepted identification

So: "You must have a REAL ID card to fly"

is incomplete.

The more accurate statement is:

you need an acceptable TSA identification document; a noncompliant ordinary state ID no longer serves as the standard accepted state credential.

REAL ID Does Not Apply to Every Kind of Travel#

REAL ID enforcement is specifically relevant to federal identification requirements such as U.S. commercial-airport checkpoint access.

It does not mean: "REAL ID is legally required whenever you travel anywhere."

A passport, for example, can serve as an alternative acceptable credential at the TSA checkpoint.

Credential Authentication Technology#

Many TSA checkpoints use Credential Authentication Technology, or CAT.

CAT can assist TSA with functions such as:

• Authenticating identification documents
• Detecting signs of fraud or tampering
• Verifying flight-reservation information
• Verifying Secure Flight screening status

Newer versions can also support identity-comparison technologies at participating locations.

The exact checkpoint workflow varies with equipment and local deployment.

The Passenger Checkpoint#

Once identity requirements are satisfied, passengers enter physical screening.

The checkpoint normally has two broad screening tasks:

1. Screen the passenger
2. Screen accessible property, including carry-on baggage

Different technologies handle different parts of that problem.

Shoes: The Old Rule Changed#

For more than two decades, removing shoes became one of the most recognizable U.S. checkpoint procedures.

That changed.

On July 8, 2025, DHS announced the end of the general shoes-off policy at TSA checkpoints.

Passengers at U.S. domestic TSA checkpoints can now generally keep their shoes on during screening.

This makes statements such as: "Every standard-screening passenger must remove their shoes"

outdated.

Individual passengers can still receive additional screening when required.

Why This Matters Editorially#

Airport-security rules evolve.

Technology changes.

Threat models change.

Risk-based procedures change.

That is why this guide should teach the security system rather than turn one year's divestment checklist into timeless aviation doctrine.

Carry-On Preparation Depends on the Lane#

Passengers should follow the instructions at the checkpoint they are actually using.

Depending on:

• Screening lane
• Technology
• Passenger status
• Airport
• Current procedure

you may be instructed differently about:

• Electronics
• Liquids
• Outerwear
• Items in pockets

Modern CT-equipped lanes can reduce the need to remove certain electronics or liquids from baggage.

Do not assume yesterday's airport procedure applies everywhere today.

Passenger Screening#

TSA uses multiple methods to screen passengers.

Common technologies include:

• Walk-through metal detectors
• Advanced imaging technology
• Physical pat-downs when required

Different passengers can receive different screening processes based on the lane and screening requirements.

Walk-Through Metal Detectors#

Walk-through metal detectors are designed primarily to detect metallic objects.

They remain useful because many potential threats contain:

• Steel
• Aluminum
• Other conductive metals

But a metal detector does not provide the same type of detection capability as advanced imaging technology.

Advanced Imaging Technology#

Modern TSA body scanners use millimeter-wave technology.

A millimeter-wave scanner uses non-ionizing radio-frequency energy to identify anomalies that may indicate concealed objects.

It does not use X-rays to scan the passenger.

Modern systems use automated target-recognition techniques rather than presenting officers with the old-style detailed passenger imagery associated with early-generation scanners.

The purpose is to identify areas requiring resolution.

A Scanner Alarm Is Not a Determination of Guilt#

A screening alarm means:

something needs to be resolved.

It does not automatically mean:

• A prohibited item was found
• The passenger committed an offense
• The object is dangerous

Resolution can involve:

• Additional screening
• A targeted pat-down
• Property inspection
• Explosive Trace Detection

depending on the situation.

Secondary Screening#

Secondary screening is an additional examination after or alongside initial screening.

It can occur because:

• Equipment alarms
• Property requires additional examination
• Screening procedures require it
• Additional screening is selected

Secondary screening is part of the layered system.

It should not be interpreted automatically as an accusation.

Pat-Downs#

A physical pat-down may be used:

• To resolve an alarm
• When another screening method is unsuitable
• As part of additional screening

Passengers can also request private screening under TSA procedures.

Checkpoint personnel should explain the process.

Carry-On Baggage Screening#

The passenger and the carry-on bag are separate screening problems.

Carry-on baggage can be screened using technology such as:

• Conventional X-ray
• Computed tomography
• Manual inspection
• ETD where needed

Conventional X-Ray#

Traditional carry-on X-ray systems produce images that trained officers use to identify:

• Prohibited objects
• Suspicious structures
• Items requiring further examination

The X-ray equipment scans the property.

Do not confuse this with the passenger's millimeter-wave body scanner.

Computed Tomography#

CT screening systems provide three-dimensional information about a bag's contents.

Officers can inspect the image from different perspectives.

The additional information can make threat detection and alarm resolution more effective and can reduce the need for passengers to remove certain items at CT-equipped lanes.

Deployment is not identical at every airport.

Explosive Trace Detection#

Explosive Trace Detection, or ETD, can test samples collected from:

• Baggage
• Property
• Other surfaces

for traces associated with explosive materials.

ETD is often part of:

• Alarm resolution
• Additional screening

rather than something every carry-on necessarily undergoes.

X-Ray Diffraction Is Not the Everyday Checkpoint Story#

The old article presented x-ray diffraction alongside ordinary checkpoint X-ray and ETD as though passengers routinely encounter all three.

That overstates its role in the normal passenger-screening workflow.

For a general airport-security guide, the core technologies worth understanding are:

• X-ray
• CT
• Millimeter-wave imaging
• Metal detection
• EDS
• ETD

Specialized detection technologies can exist elsewhere in the security ecosystem, but they do not need equal billing here.

The 3-1-1 Liquids Rule#

The U.S. TSA carry-on liquids rule continues to use the familiar:

3-1-1

framework.

For ordinary liquids, aerosols, gels, creams, and pastes:

• Each container must generally be 3.4 oz / 100 mL or less.
• Containers fit into one quart-size clear bag.
• One such bag is permitted per passenger.

This is a carry-on checkpoint rule.

It does not mean every liquid over 100 mL is universally forbidden from aviation.

Medically Necessary Liquids and Infant Supplies#

TSA permits certain exceptions to the standard 3-1-1 limit.

These include appropriate quantities of items such as:

• Medically necessary liquids
• Liquid medication
• Breast milk
• Infant formula
• Toddler drinks and food

These items can receive additional screening.

Travelers should follow TSA's current instructions when carrying them.

International Liquids Rules#

Many countries use broadly similar liquids, aerosols, and gels restrictions.

But national implementation can differ.

Some airports also deploy advanced screening systems that change what passengers need to remove from bags.

Do not assume the exact U.S. checkpoint workflow applies worldwide.

Prohibited Items Versus Dangerous Goods#

This is another distinction worth understanding.

Security-prohibited item#

A prohibited item is restricted because it can pose an aviation-security threat.

Examples can include certain:

• Weapons
• Sharp objects
• Explosives

Dangerous goods#

Dangerous goods are regulated because their physical or chemical properties can create a transportation hazard.

Examples include:

• Flammable materials
• Compressed gases
• Certain batteries
• Corrosives

An item can be restricted for:

• Security reasons
• Hazardous-material reasons
• Both

TSA primarily answers the security-screening question.

FAA/DOT hazardous-material rules govern many dangerous-goods questions.

Lithium Batteries Are a Good Example#

A power bank may not be a weapon.

But it can create a fire hazard.

Current FAA rules generally require:

• Spare lithium batteries
• Power banks
• Portable chargers

to remain in carry-on baggage rather than checked baggage.

If a carry-on is checked at the gate, those items may need to be removed and retained in the cabin.

That is a dangerous-goods/fire-safety rule, not simply a TSA prohibited-item rule.

Firearms Show the Same Distinction#

Firearms are not permitted through the passenger checkpoint in carry-on baggage.

But under U.S. rules, certain firearms can be transported in checked baggage when all applicable:

• TSA
• Airline
• Packaging
• Declaration
• Legal

requirements are satisfied.

So: "Firearms are banned from airplanes"

is too broad.

Checked Baggage Is Also Screened#

The old article largely stopped following the security process once a suitcase disappeared at check-in.

That leaves out one of the largest screening systems in the airport.

In the United States, TSA has a mandate to screen 100 percent of checked baggage.

Explosive Detection Systems#

An Explosive Detection System, or EDS, is TSA's primary checked-baggage screening technology.

Modern EDS equipment commonly uses computed-tomography principles to evaluate bags for explosive threats.

Checked baggage can move through several screening and alarm-resolution stages before being cleared.

Checked-Bag Alarm Resolution#

When automated screening cannot clear a bag, additional review can occur.

Depending on the circumstance this can involve:

• Further image review
• Physical inspection
• ETD
• Specialist or law-enforcement referral

The internal decision rules and equipment settings are security-sensitive.

The useful public concept is simply:

checked-bag screening has escalation layers just like passenger screening.

Screening and Baggage Handling Are Different#

Security screening answers:

Is the bag cleared from a security perspective?

Baggage handling answers:

How does the cleared bag physically reach the correct aircraft and destination?

The systems interact but solve different problems.

A checked bag can pass through:

• Screening equipment
• Conveyor systems
• Sorting systems
• Make-up areas
• Aircraft loading

before reaching the cargo hold.

Baggage Reconciliation#

Airlines and security systems also use controls intended to ensure that baggage accepted for carriage meets the applicable security requirements.

The exact reconciliation requirements vary by:

• Flight
• Operator
• International or domestic context
• Applicable security program

Do not reduce baggage reconciliation to the oversimplified rule: "Every passenger's bag is always removed whenever they miss every flight."

The regulatory and operational details are more nuanced.

Airport Security Zones#

The checkpoint creates one obvious security boundary.

But commercial airports contain several different regulated areas.

U.S. terminology includes:

• Sterile area
• Secured area
• Security Identification Display Area
• Air Operations Area

These terms are related but not interchangeable.

Sterile Area#

The sterile area is the passenger-accessible protected area beyond the security-screening boundary where access to aircraft is possible.

For an ordinary departing passenger:

checkpoint → sterile area → gate → aircraft

is the familiar flow.

Access must be controlled when the checkpoint is not operating as well.

Secured Area#

A secured area is an airport area subject to specific access controls because of its relationship to screened passenger-aircraft operations.

Airport operators must control and monitor unauthorized access to these areas.

A secured area is not simply: "any place behind a fence."

It is a defined regulatory security area.

Security Identification Display Area#

A Security Identification Display Area, or SIDA, is an area where authorized personnel must comply with the airport's identification and access requirements.

Under U.S. regulation:

• Every secured area is a SIDA.
• Certain cargo-related portions of the Air Operations Area must also be SIDAs.
• Other areas may be designated as SIDAs.

That means:

SIDA and secured area are not exact synonyms.

Air Operations Area#

The Air Operations Area, or AOA, covers portions of the airport used or intended for:

• Landing
• Takeoff
• Surface maneuvering
• Related aircraft activities

Airport operators must protect against unauthorized entry into the AOA.

Some or all of an AOA can also be designated as a SIDA.

Airport Badges Do Not Mean "Employees Skip Security"#

Airport employees who require unescorted access to controlled areas operate under:

• Authorization
• Identification systems
• Training
• Background/security checks
• Access restrictions

The specific process depends on the individual's role and airport.

It is incorrect to imagine: "Employees have a badge, therefore they bypass airport security."

Their access is controlled through a different security pathway.

Background Checks and Training#

For unescorted SIDA access, U.S. regulations require measures including:

• Fingerprint-based criminal-history checks
• Security training
• Airport-approved identification/access media

Personnel are authorized for the areas they need to perform their jobs.

An airport badge is not a universal key to the airport.

Escorting#

People who do not possess independent unescorted-access authority can sometimes enter controlled areas under an approved escort process.

The purpose is to preserve accountability and control.

Detailed local escort procedures are airport-security-program information and are intentionally not reproduced here.

Challenge Procedures#

Airport-security programs also require processes for identifying and responding to unauthorized presence in sensitive areas.

Again, the useful concept is:

access is continuously controlled after the checkpoint too.

Passenger screening is only one access path.

Perimeter Security#

Airports also protect the boundary between:

• Public space
• Operational airport property
• Restricted airside areas

High-level measures can include:

• Physical barriers
• Controlled access points
• Identification systems
• Surveillance
• Patrols
• Intrusion detection
• Law-enforcement response

The precise deployment, coverage, and response procedures at an individual airport are security-sensitive and vary by facility.

Security Continues on the Ramp#

The ground handling environment contains:

• Employees
• Contractors
• Vehicles
• Baggage
• Cargo
• Aircraft

all moving within restricted areas.

Security therefore includes controlling:

• Who is present
• Where they are authorized to go
• What property they can access

not simply screening airline passengers.

Cargo Security#

Passenger aircraft frequently carry cargo in addition to passenger baggage.

This is often called belly cargo.

Air cargo therefore has its own security framework involving:

• Regulated entities
• Screening
• Security controls
• Custody and access protection

The exact requirements differ between:

• Passenger-aircraft cargo
• All-cargo operations
• Domestic and international systems

Cargo security is a separate layer from passenger carry-on screening.

Security Does Not End When You Board#

Once passengers enter the aircraft, additional layers exist.

These can include:

• Controlled flight-deck access
• Airline security procedures
• Trained cabin and flight crews
• Law-enforcement coordination
• Federal Air Marshal capabilities
• Passenger-management procedures

The exact deployment of onboard law-enforcement resources is intentionally not public operational information.

Federal Air Marshal Service#

The Federal Air Marshal Service is TSA's law-enforcement arm for civil-aviation and transportation security.

Its mission extends beyond what passengers see at checkpoints.

Publicly useful information is limited to the fact that FAMS supports:

• Aviation-security law enforcement
• Threat mitigation
• Transportation-security operations

Operational deployment details should not be treated as public trip-planning information.

Hardened Flight Decks#

Modern airliner flight decks also operate under controlled-access procedures.

After the September 11 attacks, flight-deck security became a major part of the broader layered-security model.

Aviation security therefore protects:

airport → aircraft → cockpit

rather than stopping at the checkpoint.

What Happens During a Security Incident?#

Different incidents can trigger different organizations.

Depending on the event, responses may involve:

• TSA
• Airport operations
• Airport police
• Local or federal law enforcement
• Airlines
• Emergency services

Examples include:

• A prohibited item at a checkpoint
• An unattended bag
• Unauthorized access
• A security-boundary breach
• A threat involving an aircraft

The response is situation-specific.

Sterile-Area Breaches#

If the integrity of a protected passenger area cannot be assured, authorities may need to:

• Restrict movement
• Clear affected areas
• Re-screen passengers

That can create significant delays even when no aircraft itself has been compromised.

See Flight Delays & Cancellations Explained.

Airport Police and TSA Are Not the Same Thing#

TSA officers perform transportation-security functions.

They are not the ordinary police force for the airport.

Criminal matters can be referred to:

• Airport police
• Local law enforcement
• Other appropriate authorities

That is why discovery of a firearm or another illegal item can transition from:

security screening

to:

law-enforcement action.

TSA Is Not Primarily Looking for Drugs#

TSA's checkpoint mission is to detect threats to transportation security.

TSA is not a general narcotics-enforcement agency.

If officers encounter suspected illegal drugs while performing security duties, the matter can be referred to law enforcement.

TSA PreCheck#

TSA PreCheck is a risk-based expedited-screening program.

Eligible travelers can receive a modified checkpoint process.

PreCheck does not mean:

• No screening
• Guaranteed expedited screening every time
• Exemption from prohibited-item rules

It is a different screening pathway within the same security system.

CLEAR Is Different From TSA PreCheck#

CLEAR is a private identity-service provider at participating airports.

It is not:

• TSA
• Secure Flight
• TSA PreCheck

CLEAR can provide an expedited identity-verification pathway at participating locations.

Passengers still undergo required TSA security screening.

The two products solve different parts of the passenger journey.

Do Not Memorize One PreCheck Price#

The old article hard-coded:

$78 for five years

as though that were a permanent program fact.

TSA now supports multiple enrollment providers, and fees can change.

For evergreen editorial content, it is better to tell readers to check the current TSA enrollment page.

Do Not Memorize Checkpoint Wait-Time Promises Either#

Statements such as: "Security normally takes 10–20 minutes"

or: "PreCheck always takes under five minutes"

are too brittle.

Checkpoint time depends on:

• Airport
• Terminal
• Time of day
• Staffing
• Passenger volume
• Screening lane
• Equipment
• Irregular operations

A security guide should explain the system rather than promise a queue length.

International Airport Security#

ICAO provides the international aviation-security framework through Annex 17 — Aviation Security.

Its objective is to establish international Standards and Recommended Practices for protecting civil aviation from acts of unlawful interference.

But ICAO does not operate the passenger checkpoint at Heathrow, Frankfurt, Singapore, or Delhi.

Each State implements its own:

• Regulations
• Security authority structure
• Screening procedures
• Access-control requirements

So TSA procedures should never be taught as universal world airport rules.

ICAO Security Guidance Is Intentionally Restricted in Part#

ICAO's detailed Aviation Security Manual, Doc 8973, has restricted distribution.

That is appropriate.

Aviation security requires enough public information for:

• Travelers
• Operators
• Education
• Regulatory understanding

without publishing detailed information that could assist attempts to defeat protective systems.

General Aviation Airports Are Different#

A small general-aviation airport may have:

• No passenger checkpoint
• No TSA screening lane
• No sterile passenger concourse

That does not mean:

no security exists.

Security measures can instead involve:

• Aircraft access
• Hangars
• Gates
• FBO procedures
• Airport access controls
• Local security measures

A large scheduled-airline terminal and a small GA airport should not be described as though they use the same security architecture.

Why Airport Security Is Layered#

Imagine that one control fails.

A layered system still has other opportunities to:

• Detect
• Deter
• Prevent
• Respond

That is the basic rationale for combining:

• Intelligence
• Vetting
• Identity
• Screening
• Access control
• Baggage screening
• Cargo controls
• Law enforcement
• Aircraft security

No layer needs to be treated as infallible for the architecture to be useful.

Common Myths About Airport Security#

Myth: Airport security starts at the TSA checkpoint#

No.

Passenger vetting begins before arrival, and baggage, employee, cargo, access-control, perimeter, and onboard layers exist beyond the checkpoint.

Myth: TSA runs every part of airport security#

No.

Airport operators, airlines, law enforcement, contractors, and other organizations have major responsibilities.

Myth: Every U.S. checkpoint is staffed by federal TSA officers#

No.

Some airports participate in TSA's Screening Partnership Program and use private contract screeners operating under TSA standards and oversight.

Myth: TSA still requires everyone to take off their shoes#

No.

The general shoes-off policy ended on July 8, 2025.

Myth: The body scanner X-rays passengers#

No.

Current TSA advanced imaging uses non-ionizing millimeter-wave technology.

Carry-on baggage X-ray is a different system.

Myth: PreCheck means you are not screened#

No.

PreCheck provides expedited risk-based screening.

Myth: CLEAR and TSA PreCheck are the same thing#

No.

CLEAR primarily addresses identity processing at participating locations.

PreCheck changes the TSA screening pathway for eligible passengers.

Myth: An airport badge lets employees bypass security#

No.

Employees with unescorted access operate through a regulated identification, authorization, training, and access-control system.

Myth: All checked baggage simply disappears into the baggage system after check-in#

No.

U.S. checked baggage is subject to TSA screening before transportation.

Myth: Security-prohibited items and dangerous goods are the same thing#

No.

Security rules address deliberate-threat concerns.

Dangerous-goods rules address hazards such as fire, chemical, or pressure risks.

Some items fall under both.

Myth: REAL ID is the only ID accepted for U.S. air travel#

No.

REAL ID-compliant state identification is one option. TSA accepts other approved documents such as passports.

Myth: Security and immigration are the same process#

No.

TSA aviation screening and border/customs controls serve different functions.

Myth: Every airport in the world follows TSA procedures#

No.

ICAO provides a global framework, but States implement aviation security through their own laws and systems.

Frequently Asked Questions#

Key Takeaways#

• Airport security is a layered system, not just a passenger checkpoint.
• Security and aviation safety are related but distinct disciplines.
• TSA is a major U.S. aviation-security agency, but airports, airlines, law enforcement, and other organizations also have security responsibilities.
• Some U.S. airports use private checkpoint screeners under TSA's Screening Partnership Program.
• Secure Flight passenger vetting occurs before the physical checkpoint.
• Passenger vetting, identity verification, and physical screening are separate security functions.
• REAL ID enforcement began at TSA checkpoints on May 7, 2025, but other TSA-approved identification can also be used.
• CAT systems help authenticate identity credentials and verify flight and screening information.
• The general TSA shoes-off policy ended on July 8, 2025.
• Checkpoint divestment rules can vary with lane technology and local instructions.
• Walk-through metal detectors and millimeter-wave scanners solve different screening problems.
• TSA advanced imaging uses non-ionizing millimeter-wave technology rather than passenger X-rays.
• Screening alarms require resolution; they are not themselves findings of wrongdoing.
• Carry-on baggage can be screened using X-ray, CT, inspection, and ETD.
• The U.S. 3-1-1 carry-on liquids rule remains in effect, with exceptions for medically necessary and certain infant-related liquids.
• Prohibited-item rules and dangerous-goods rules are not the same thing.
• Spare lithium batteries and power banks must remain in carry-on baggage under current FAA rules.
• TSA maintains a 100-percent U.S. checked-baggage screening mandate.
• EDS is the primary TSA checked-baggage screening technology.
• Checked-baggage security and baggage handling are different systems.
• Sterile areas, secured areas, SIDAs, and AOAs are related but distinct airport-security concepts.
• Employees with unescorted access operate under identification, authorization, training, and security-check requirements rather than simply "skipping security."
• Airport operators must maintain access control and response systems for regulated airside areas.
• Cargo security forms another layer beyond passenger and baggage screening.
• Federal Air Marshals are part of TSA's aviation-security law-enforcement capability.
• TSA screening and customs/immigration serve different purposes.
• TSA PreCheck is expedited screening, not an exemption from screening.
• CLEAR is a private identity service and is not the same thing as TSA PreCheck.
• ICAO Annex 17 provides the international framework, while individual countries implement their own security systems.
• Small general-aviation airports do not necessarily use the passenger-checkpoint model found at large airline terminals.
• Detailed airport security-program procedures are intentionally protected; useful public education should explain the system without publishing ways to defeat it.

Sources & References#

• Transportation Security Administration, current passenger screening, identification, prohibited-items, liquids, TSA PreCheck, Secure Flight, and screening-technology guidance.
• DHS/TSA, July 8, 2025: End of the general U.S. passenger shoes-off checkpoint policy.
• TSA, Credential Authentication Technology and Checkpoint Requirements and Planning guidance.
• TSA Checked Baggage Capability Maturation Roadmap and current checked-baggage screening documentation.
• 49 CFR Part 1540 — Civil Aviation Security: General Rules.
• 49 CFR Part 1542 — Airport Security.
• 49 CFR Part 1544 — Aircraft Operator Security: Air Carriers and Commercial Operators.
• 49 CFR Part 1546 — Foreign Air Carrier Security.
• FAA PackSafe guidance and 49 CFR hazardous-material rules for dangerous goods in passenger baggage.
• ICAO Annex 17 — Aviation Security, 12th Edition, July 2022, with current amendments/corrigenda as applicable.
• ICAO Aviation Security Policy Section public guidance. Detailed Aviation Security Manual Doc 8973 has restricted distribution.