Good day all, I am sure you might have had this question before but as a new user of iPad I need to understand if I have a faulty GPS chip or if there is something I do wrong? I bought the iPad 2 about 3 weeks ago, Wi-Fi with 3G capability to use while flying with Air Nav Pro, this application makes use of the internal IMU and GPS to work out the route you have planned and to ensure proper navigation. I used it once while flying and it seemed to have worked fine, but was unable to keep my eye on it all the time. Yesterday I decided to take it with while flying with the domestic carrier from Cape Town to Johannesburg to see how it works in real time, not having to focus on doing the flying myself. I removed the Sim Card from the iPad as I had to leave it at home, but Nav pro seemed to be fine and was working well on the ground, giving me the longs and lats and rotating the chart as I moved, I found my seat in the aircraft very excited to see which track they would fly and the altitude, groundspeed and all the usual nonsense a pilot would love to see. We began our take-off roll at Cape Town and the iPad and Nav Pro seemed to be working fine, on the climb I could see the altitude increase as well as the ground speed creeping up. We made a right turn as anticipated on the flight path I plotted and at about 30nm outbound the GPS just stopped working??? No info just a black icon where the GPS info should be? Check the whole flight and nothing!!! Landed at Johannesburg very upset as I was unable to see if my plotted track was the same as what they flew, and still the GPS icon remained black! Inside the terminal building I thought to check again and by some miracle the GPS was back? To keep the story short, I tested it on my second leg of traveling and the same thing happened? Any logical explanation why this happen? Do I need to have the SIM card installed all the time? This just baffles my mind at the moment! Would like to know if someone can help in this regard?