Personal Devices
Assuming Wi-Fi or Bluetooth delivery of data to portable devices, passenger-download apps to phones or tablets could be an effective delivery method provided the devices are turned on and the apps are running while on the plane.
Similar to emergency-alert systems that many people use today on the ground, the devices could be forced to vibrate or emit a sound when a message is received.
Portable devices that are distributed by airlines to passengers could have the alert app enabled automatically when the devices are handed out.
Each lavatory would not need to contain a display for text alerts if assuming passengers carry PEDs or other portable devices into lavatories.
A personal device is a portable, battery-powered device with wireless capability.