I would like to get a list of all the wireless networks.

iwlist wlan0 scan | grep ESSID

This will only show me the wireless network I am currently connected to. When I run the command as root, it shows me all the available networks. If I run the command without sudo quickly after this, all the networks will show up, but after a while they are all gone except the network I am currently connected to.

Is there a way to get all the available networks when I am not root?