Yes, airports use two main TSA scanner types: body screening for people and X‑ray or CT machines for bags, and you’ll pass both at most checkpoints.
That short question pops up the moment a traveler faces the lane: one arch to walk through and one tunnel for carry‑ons. The wording “two TSA scanners” fits, though the setup blends several tools. People are screened by either a walk‑through metal detector or a millimeter wave body scanner. Bags ride through an X‑ray or newer computed tomography unit that builds a 3D view. You meet both families on a standard trip.
Scanner types at a glance
Here is a quick map of what each machine looks at and why you might see it on your next flight.
| What It Scans | Core Equipment | Primary Purpose |
|---|---|---|
| People | Walk‑through metal detector (WTMD) | Finds metal objects carried on the body |
| People | Millimeter wave body scanner (AIT) | Checks for concealed items, metal or non‑metal |
| Carry‑on bags | 2D X‑ray conveyor | Flat image to spot dense or odd shapes |
| Carry‑on bags | Computed tomography (CT) checkpoint unit | 3D image for better threat resolution |
| Photo ID | Credential Authentication Technology (CAT) | Validates ID and flight details |
Why there seem to be two TSA scanners at checkpoints
The lane is split into two tracks that run in parallel. One is for your body; the other is for property. This is why it feels like “two scanners.” Officers direct you to the body portal while your bins enter the tunnel. When both lanes clear, you move forward, collect your things, and step away. The choreography keeps people moving while officers watch both streams.
People screening: metal detector or body scanner
Two tools handle people screening. The walk‑through metal detector is fast and familiar. If it stays quiet, you move on. If it alarms, an officer checks the area that set it off. The millimeter wave body scanner looks for more than metal and shows a generic figure with any flagged spots marked on a simple outline. Many lanes use one or the other based on layout, screening level, and traveler program.
Metal detector at a glance
The metal detector senses items like knives, tools, belt buckles, steel shanks, and stray coins. Small things often pass in the PreCheck lane, while standard lanes ask for more items to be removed. Empty your pockets, tuck watches and large jewelry in a bin, and you’ll glide through that arch.
Millimeter wave body scanner basics
The body scanner uses low‑power radio waves in the millimeter band to check for hidden items on the surface of clothing. It does not use medical X‑rays. You stand on the footprints, hold still for a second, and wait for the “OK” on the screen. If the unit shows a box on the outline, the officer will clear that area with a brief pat‑down or ask you to adjust clothing and try again.
Bag screening: X‑ray versus CT
Carry‑on bags go through either a classic X‑ray or a newer CT unit. A 2D X‑ray stacks flat slices and can hide layered items. CT rotates the bag and builds a 3D view that an officer can spin on screen. With CT, many airports let you leave laptops in the bag and keep small liquids where local rules allow. With either system, clutter slows review, so pack with clean layers and use bags with simple compartments.
Are there two TSA security scanners for bags?
Yes, there are two checkpoint systems for cabin bags in use today. The first is the long‑standing 2D X‑ray belt. The second is the CT checkpoint machine that creates a volumetric image. Both look like a dark tunnel with rollers, though the CT unit tends to have a larger scanner head and a short pause while the bag rotates. If your airport has CT lanes, you may keep electronics inside your bag and see fewer manual checks when packing is tidy.
Rules still apply to liquids. The 3‑1‑1 standard sets a limit for travel‑size containers in a single quart‑size bag where that policy is enforced. Oversized liquids go in checked luggage unless exempt for medicine or special needs. Pack light in the bin and keep your bag free of food slurries, loose chargers, and tangled cables.
What each scanner can and cannot see
Each device targets a narrow task. A metal detector finds metal, not plastic or paper. A body scanner looks for objects on the surface of clothing and marks a region if it senses an anomaly. It does not view inside the body. A 2D X‑ray shows density on a flat image; glass or thick ceramics can hide items in a cluttered bag. CT solves many of those blind spots by rotating the bag and letting officers slice through the image from multiple angles.
Knowing those limits helps you pack. Hard blocks of cheese, brick‑style makeup palettes, tightly stacked books, and bags full of cables often trigger bag pulls. Spread heavy items apart and use pouches to separate chargers, toiletries, and snacks. When the image is clean, your bag glides past the operator and drops onto the rollers with no delay.
What happens when a scanner flags something
Alerts are common and usually quick to resolve. Officers will rescreen the item, ask a question, or perform a short check. Here is what those moments look like and how to avoid repeat trips through the lane.
| Trigger | Typical follow‑up | Prevention tip |
|---|---|---|
| Bulky pocket item in the body scan | Brief pat‑down or remove item and rescan | Empty pockets into a bin before you enter |
| Dense block in a carry‑on | Bag pulled for a quick open‑bag check | Spread items; avoid stacking books or gear |
| Unclear laptop in a 2D lane | Officer asks to send laptop alone | Use a sleeve and remove it the first time |
| Liquid above size limit | Item discarded or returned to your car | Use travel bottles; keep only one quart bag |
| Alarm at the metal detector | Hand wand or targeted pat‑down | Remove belts and heavy jewelry in standard lanes |
Tips to move through both scanners faster
Plan like a pro and those machines become a brief pause, not a hurdle. These simple habits shave minutes off busy mornings.
- Use a front pocket for your phone and empty it before you step up.
- Pack carry‑ons with tidy layers so the image is easy to read.
- Choose slip‑on shoes and light outerwear during peak travel days.
- Place snacks in a clear pouch to cut down on food bag checks.
- Keep meds and medical items together with any supporting papers.
Privacy, health, and opt‑out choices
Millimeter wave body scanners run on non‑ionizing radio waves. That energy does not add to an X‑ray dose. The display shows a generic figure, not a photo of your body. If the unit alarms, officers only check the marked spot. Most travelers may choose a manual screening in place of the body scan. Rarely, officers may require the body scan for security reasons. Kids, those with mobility aids, and travelers with a medical device can get tailored screening with help from officers on duty.
Checked bags: the other screening you don’t see
Behind the ticket counter sits a second world of machines built for checked luggage. Airports use large explosive detection systems fed by conveyor. Many of those systems use computed tomography to build 3D images of each suitcase while it moves toward the sorting hall. If the system marks a bag, it goes to a resolution area where officers clear the alert. This all happens out of sight and does not affect the checkpoint process unless you are called back to open a bag.
PreCheck lanes and the “two scanners” idea
Travelers with PreCheck usually meet a metal detector for the body scan and may keep shoes, belts, and light jackets on. That lane can still use the millimeter wave portal at times. On the bag side, many PreCheck lanes now have CT units, which means laptops often stay inside and small liquids remain packed when local policy allows. The flow is the same: body lane plus bag lane, two quick scans, and you are on your way.
Special items and medical needs
Traveling with a prosthetic, insulin pump, ostomy supplies, breast milk, baby food, or formula calls for a short chat with the officer at the front of the lane. Place those items in a separate pouch and tell the officer before screening starts. You may see a swab test for trace explosives on bottles or devices. That test takes seconds and uses a small piece of paper wiped on the surface of the item. Most travelers are on their way right after that check.
Lane choice and timing
Most airports post signs near the queue that list lane types: standard, PreCheck, and sometimes a family or assistance lane. Pick the lane that matches your ticket and needs. If you carry items that must be removed in a 2D lane, such as a game console or video camera, look for a CT lane if one is available. That swap alone can save a rescreen and a bag check.
Putting it all together at the lane
Think of the process as two quick scans with short choices along the way. Hand your ID to the officer or the CAT unit, place bins on the rollers, then step to the body portal you are sent to. Keep pockets empty, hold still, and watch for the screen to read “OK.” Grab your gear, check the bin for stray items, and move clear of the belt before you reassemble. With clean packing and calm steps, the whole pass often takes just a few minutes.
Helpful links for travelers
Want official details on the machines you’ll meet? See the TSA security screening page for body screening basics, read about the TSA computed tomography program for carry‑on lanes, and review the 3‑1‑1 liquids rule before you pack.