TSA CT Scanner Rollout Narrows Carry-On Space at US Airports

New Scanners Force Baggage Re-routing

The United States Transportation Security Administration (TSA) has spent USD781.2 million to retrofit security checkpoints at hundreds of airports with new computed tomography (CT) scanners.

While these advanced units allow passengers to keep laptops and travel-size liquids inside their bags during screening, they feature a narrower tunnel opening than the older X-ray machines they replace. This physical constraint is increasingly leading to ordinary rolling carry-on luggage being turned away at security and sent back to airline ticket counters for checking.

The effective size limit for bags passing through security has changed due to the machinery, not because of any alteration to airline carry-on allowance policies.

Physical Dimensions and Policy Shifts

The core issue stems from the CT units' tunnel dimensions, which are approximately 24.5 inches wide by 16.5 inches tall (62.2 by 41.9 cm). This is smaller than many older X-ray machines, with a difference of 0.4 to 0.7 inches (1.0 to 1.8 cm) per side. As of July 6, 2026, the TSA had installed 1,162 CT units across 296 airports.

This rollout commenced with limited testing in 2018 and accelerated following the agency's USD781.2 million contract award for the technology in 2022.

Concurrently, on August 24, 2026, newly confirmed TSA Administrator David P. Cummins unveiled the 'Horizon 25' strategy, which includes retiring the TSA Gold+ programme in favour of an expanded and more privatised Screening Partnership Programme (SPP). These mechanical and administrative changes are simultaneously reshaping airport security procedures.

Why Bags That Meet Airline Limits Are Rejected

While a standard airline carry-on measuring around 22 by 14 by nine inches (56 by 36 by 23 cm) typically clears the new CT tunnel, problems arise with larger, expandable 'maximum-capacity' roller bags. These models are often built to the outer edge of airline allowances and can bulge when fully packed.

A bag that fits through an older X-ray tunnel with clearance may become too wide or tall once its expansion section is filled, exceeding the CT scanner's smaller opening. This creates a discrepancy between the airline's baggage allowance and the physical opening of the scanner.

The CT units generate rotatable, high-resolution 3D images, which is why laptops and permitted liquids no longer need to be removed, and officers open fewer bags by hand. However, a smaller entry tunnel is the trade-off for this improved imaging capability, a detail not widely communicated by the agency during the upgrade process.

Consequences for Travellers

When presented with an oversized bag, TSA guidance indicates officers can hand-inspect it, redirect it to a lane with older equipment if available, or advise the traveller to check it with the airline. The latter option is increasingly becoming the default at CT-equipped checkpoints, as the agency has stated that some larger carry-ons simply will not fit.

This outcome carries tangible costs beyond inconvenience. A bag rejected after clearing the security line often necessitates returning to the ticket counter, paying a same-day checked-bag fee, and potentially missing a boarding cutoff. Furthermore, the higher-powered imaging used by CT scanners can fog or ruin undeveloped photographic film, a specific risk for some travellers.

The agency's communication focused on faster screening, with little warning about the narrower openings, catching many travellers unprepared.

What This Means For Travellers

Travellers departing from US airports should be aware of these changes. To avoid potential delays and unexpected checked-bag fees, it is advisable to precisely measure carry-on bags when fully packed, especially if using expandable models. Opting for non-expandable luggage that comfortably meets standard airline dimensions may help ensure smooth passage through security.

Additionally, those travelling with undeveloped photographic film should consider alternative methods for transport, such as hand-inspection, to prevent damage from the CT scanners. Airlines may need to prepare for an increase in last-minute checked baggage and consider clearer communication regarding the effective dimensions for carry-on items at security checkpoints.