The GPS's may not work inside the plane.You must have an 'clear sky'in order to get satelite reception.The small window from the pax is not enaugh. The windows from the cockpit have metal shielding (for antiice) and you won't get any reception either. I've tried my magellan GPS, no result.
I've used it on older planes,but it was a different type of windows on the cockpit.