Frontier & Southwest Airlines Allow 24-Inch Carry-Ons, But TSA's New CT Scanners Leave Half An Inch To Spare

Air travelers flying with larger carry-on bags are facing a new practical constraint at US airport security checkpoints. Frontier Airlines and Southwest Airlines both allow cabin bags measuring up to 24 by 16 by 10 inches (61 by 41 by 25 cm), while the newer computed tomography, or CT, scanners being installed by the Transportation Security Administration (TSA) have tunnel openings of approximately 24.5 inches (62 cm) wide by 16.5 inches (42 cm) high. A maximum-size bag can therefore fit on paper, but it has only about half an inch of clearance in the two dimensions that matter at the scanner entrance.