Never brought a scanner on board but when small GPS units first came out brought one on board. It works if held up to the window and is at the right angle. I was sitting upstairs on a 747-400 and one of the pilots came out and saw it. At then time he had never used one of the hand held type--so he was very interested in it. He wanted to check was the accuracy of my GPS versus plane's GPS. Asked me if he could take it to the cockpit for a few minutes. Came back about 20-minutes later and reported that it was pretty close to plane's GPS.