Distance measure is more accurate walking away than walking towards a beacon

I've been testing with these for a about a month. One thing that I notice is that when walking away from a beacon, the distances are fairly accurate, however, if I turn around and walk back towards a beacon, it takes roughly 3 times the time interval for the distance to catch up.

Test result: I had a helper walk away from my device with one of the Estimotes set at -4 power and 50ms. As he walked to a distance of 4 meters, the distance kept fairly good track. However, when he turned around and walked back in a period of 5 seconds to cover the 4 meters, the time it took the message to hit beaconManager:didRangeBeacons:inRegion: to about 3 times as long to catch up as walking away.

Is there anything like kCLLocationAccuracyBest that can be set?

There is not anything like kCLLocationAccuracyBest that can be set.

When you say that you turned around and walked back, do you mean that between beacon and phone there was a person? If so, this introduces quite big Bluetooth signal attenuation. Bluetooth is based on 2.4 GHz which is easily absorbed by water and humans are mainly water.