William Thackray, an IT expert at AGT Computer Services, told the Daily Express that scanners need a clear, bright image to read a barcode or QR code reliably. In bright airport lighting, a screen at default brightness or dimmed to save battery can cause a failed scan. He described the issue as trivial but avoidable, yet it holds up queues.
To avoid problems, Thackray recommends increasing screen brightness to maximum before travel and screenshotting the boarding pass to avoid reliance on signal or Wi-Fi. He also advises disabling auto-lock or increasing screen timeout to 2-3 minutes to prevent the screen from going dark mid-queue. Additionally, ensuring the phone is fully charged is important because some airports may ask travelers to power up their device at security.