Certain portable electronic devices (PEDs) may interfere with aircraft navigational e quipment. PED use is permitted while on the ground when the boarding door is open, a nd in flight when advised by crew members. About 10 minutes before departure, passengers will be asked to turn off computers, cell phones and other PEDs. T he following PEDs are approved for use during the flight time: ? Personal Computers ? Handheld computer games ? Personal stereo and video devices Medical devices are permitted at all times while TVs, radios, two-way radios, remote-control devices and some other electronic devices are not permitted. Due to safety concerns, the crew may at any time request that PEDs be turned off. Cell phones may be used only in the following instances: ? When the aircraft is at the gate and the boarding door is open. ? When the aircraft is on the ground away from the gate and the captain has approved their use. What is the possible bad effect of using a PED on an aircraft in flight? The aircraft navigational equipment may be ______.