Use -v or -vv for full protocol decode on wi0, link-type IEEE802_11 (802.11 plus BSD radio information header) Use option -y to set: Wi0 mediaopt monitor channel 1 up, use option -i wi0 -L to listen to the link type IEEE 802.11_11. Use option-option -y – to set to set link types: IEEE 802802_10 (Ethernet) and IEEE 802/11_RADIO (BSD)”]
Source: https://taosecurity.blogspot.com/2005/04/wireless-traffic-snippets-in-my-usenix.html