Oh no, not this ridiculous debate again. Cell phones, WiFi, GPS receivers, toasters, et al. do not interfere with navigation. All of these devices are already allowed, or are being considered to be allowed, for use in flight. Not to mention the hundreds of people each day who already accidentally use them in flight by forgetting to turn them off (OK except perhaps for toasters). The reasons they are banned in some cases currently has to do with completely non safety related reasons.