If someone will find this topic I've got one remark.
Initializing the monitor mode in 'separate lines' (like in the post above) didn't work for me.
I had to do it in one line with:
ifconfig wlan create wlandev ath0 wlanmode monitor
ifconfig wlan1 up
Interface options for reference:
wlan1: flags=8943 <up,broadcast,running,promisc,simplex,multicast>metric 0 mtu 1500
ether 00:80:48:64:63:57
inet6 fe80::280:48ff:fe64:6357%wlan1 prefixlen 64 scopeid 0xb
nd6 options=43 <performnud,accept_rtadv>media: IEEE 802.11 Wireless Ethernet autoselect mode 11g <monitor>
status: running
ssid "" channel 11 (2462 MHz 11g) bssid 00:80:48:64:63:57
regdomain ETSI country NL ecm authmode OPEN privacy OFF txpower 30
scanvalid 60 protmode OFF wme burst</monitor></performnud,accept_rtadv></up,broadcast,running,promisc,simplex,multicast>