What you can do, is move the gps out of the plane and into open air to see if the gps receives a lock quicker, and this will let you know more if it is the "uAvionix hockey puck GPS" interfereing, ot the GPS itself. After you go though all the cold starting, and moving around, and you decide it is the GPS, give support a call, and we can see what we can do to help you. As for an external antenna, this would work great. The one we sell comes with a 10' Cable, so it will easily mount anywhere you might want it.