Yes, every piece of checked luggage on a commercial flight is scanned before it goes anywhere near the aircraft. In the United States, the TSA screens 100% of checked bags, and international standards set by the International Civil Aviation Organization require the same globally. Your bag goes through a multi-step screening process that happens entirely behind the scenes, between the moment you hand it to the airline and when it’s loaded into the cargo hold.
How Checked Bags Are Screened
After you drop your bag at the check-in counter or bag drop, it enters a conveyor belt system called a Baggage Handling System. This network of belts routes your luggage through security screening equipment that’s built directly into the airport’s infrastructure. At most major airports, the scanning machines are fully inline, meaning bags move through them automatically without anyone needing to pick them up or carry them to a separate area.
The primary screening tool is an Explosive Detection System, which uses a form of CT scanning (the same basic technology behind medical CT scans) to create detailed, three-dimensional images of your bag’s contents. These machines are specifically calibrated to detect explosives, but they also reveal the shape, density, and composition of everything inside. The system can distinguish between a folded shirt, a bottle of shampoo, and a block of something suspicious based on how the material absorbs X-ray energy.
If the automated system flags something, the bag moves to a second level of screening. A trained officer reviews the scan images on a monitor and decides whether the bag needs to be physically opened. If it does, a third level involves a hands-on inspection. Most bags clear the first automated scan without any human involvement at all.
What the Scanners Are Looking For
The primary target is explosives. That’s the reason these systems exist and what they’re optimized to find. But the CT-based scanners produce such detailed images that officers can also spot weapons, large quantities of drugs, and other prohibited items. Newer systems incorporate AI-powered automated threat recognition, which uses deep learning algorithms trained on thousands of X-ray images to flag suspicious objects in real time. The TSA has funded development of these systems, and functional prototypes are already integrated into scanning equipment at airports.
The scanners are also looking for items that pose a fire risk in the cargo hold. Spare lithium batteries and portable power banks are banned from checked luggage because they can overheat and ignite. Lithium batteries installed in devices like laptops or cameras are allowed in checked bags, as long as each battery is rated at 100 watt-hours or less. Spare batteries over 100 watt-hours, along with all uninstalled power banks and phone chargers containing lithium cells, must go in your carry-on. Arc lighters and electronic lighters are also prohibited in checked bags.
What Happens If Your Bag Gets Flagged
If your bag triggers an alarm during the automated scan, it doesn’t mean you’re in trouble. Dense items, unusual shapes, or certain organic materials can all cause a flag. The bag gets diverted to a secondary screening area where an officer examines the scan more closely. In many cases, the officer can clear the bag just by reviewing the image from a different angle or with enhanced settings.
When a bag does need to be physically opened, TSA officers will inspect the contents and then place a printed Notice of Baggage Inspection inside before closing it back up. This slip is your confirmation that someone went through your belongings. The TSA can also inspect bags randomly, even when no alarm is triggered.
If you lock your checked bag, use a TSA-approved lock. These are sold under brands like Travel Sentry and Safe Skies, and the TSA holds universal master keys that let officers open them without cutting. If you use a non-approved lock, they’ll cut it off. The TSA is straightforward about this: they will remove anything that prevents them from completing an inspection.
Privacy and Your Rights
There’s no opt-out for checked bag screening. By checking a bag on a commercial flight, you consent to having it scanned and potentially opened. The legal authority for this falls under federal aviation security regulations, and it applies to every passenger equally.
That said, there are some protections in place. Individual airports are responsible for access control and video monitoring of the areas where checked bags are screened. Methods vary by airport but often include CCTV surveillance of the inspection zones, which creates a record if something goes wrong. If your property is lost or damaged during the screening process itself, you can file a claim directly with the TSA. If damage happens during transport to the plane or at baggage claim, that’s the airline’s responsibility.
How This Differs From Carry-On Screening
The screening you walk through at the security checkpoint uses different equipment than what scans your checked bags. Carry-on screening happens in front of you using smaller X-ray machines and, increasingly, CT scanners similar to the ones used for checked luggage. Checked bag screening happens in a restricted area you never see, uses larger industrial-scale machines, and is heavily automated.
The key practical difference: checked bags go through explosive detection as their top priority, while carry-on screening focuses more on weapons and items that could be used to interfere with a flight. This is why certain items like large bottles of liquids or full-size tools are fine in checked bags but banned from carry-ons, while spare lithium batteries are the reverse. Each screening layer addresses a different set of risks based on where in the aircraft those items will end up.