Indeed, without going into orbit, a vomit comet would be the best. Even if you dropped the phone from the tallest building (assuming it would be tall enough, wh

Indeed, without going into orbit, a vomit comet would be the best. Even if you dropped the phone from the tallest building (assuming it would be tall enough, which it isn't), the phone would soon register more-than-microgravity acceleration due to air resistance. The phone will most definitely notice 0-g after "equilibrium." Pretty much at all times (unless being accelerated by your hand or your carelessness), the iPhone registers a 1-g acceleration towards the ground... much like almost every other static accelerometer you can buy.