A portable GPS shows you where you are on a map and gives you step-by-step directions to reach your destination. In an unfamiliar location, you have information at your fingertips to make finding your way easier. If you decide to take a GPS with you when you fly, know the rules for when and where you may carry and use it. Avoid problems with security staff or airline personnel by following any instructions given by flight crew members.The U. S. Transportation Security Administration advises all electronics should be packed in carry-on luggage. They also advise that you pack your electronic items carefully to prevent them switching on inadvertently during travel. If you are carrying spare lithium batteries for your devices, these may not be packed loose in checked baggage, but must also be packed in carry-on luggage.Portable GPS units may be left in carry-on luggage during security screening. You are not required to remove them from luggage and put them through screening separately as you would a laptop, for example. The TSA recommends packing carry-on items neatly in layers so the screening equipment can recognize individual devices. Packing everything jumbled together may confuse the screening machinery and cause you to have to wait through a manual inspection of your carry-on luggage.Like other portable electronics, GPS units may be used while the aircraft is still at the gate. The flight crew will make an announcement prior to take-off when all electronic devices must be turned off. The flight crew will make another announcement after the aircraft reaches a height over 10,000 feet and they determine it is safe for passengers to resume using approved portable electronics. In preparation for landing, flight crew will once again request passengers to turn off all electronic devices until the aircraft is on the ground and parked at the gate.Certain airlines prohibit the use of portable GPS units during flight. According to the Federal Aviation Administration this policy is at the discretion of the airline, but the FAA does require that the airline inform passengers about permitted and prohibited devices in the pre-flight briefing and in written materials. You can check in the literature provided in the seat pocket in front of you on the aircraft for a list of approved electronics or ask a flight attendant if you're not sure. In all cases, if a flight attendant asks you to turn off an electronic device for any reason, do so immediately.