root@kali:~# airodump-ng wlan0monmon
ioctl(SIOCSIWMODE) failed: Device or resource busy

ARP linktype is set to 1 (Ethernet) - expected ARPHRD_IEEE80211,
ARPHRD_IEEE80211_FULL or ARPHRD_IEEE80211_PRISM instead.  Make
sure RFMON is enabled: run 'airmon-ng start wlan0monmon <#>'
Sysfs injection support was not found either.

root@kali:~# airmon-ng start wlan0monmon
Found 5 processes that could cause trouble.
If airodump-ng, aireplay-ng or airtun-ng stops working after
a short period of time, you may want to kill (some of) them!

  PID Name
  558 NetworkManager
  720 dhclient
  891 avahi-daemon
  892 avahi-daemon
  900 wpa_supplicant

PHY	Interface	Driver		Chipset

phy0	wlan0monmon	rt2800usb	Ralink Technology, Corp. RT5370
		(mac80211 monitor mode vif enabled for [phy0]wlan0monmon on [phy0]wlan0monmonmon)
		(mac80211 station mode vif disabled for [phy0]wlan0monmon)


root@kali:~# airodump-ng wlan0monmon
Interface wlan0monmon:
ioctl(SIOCGIFINDEX) failed: No such device
root@kali:~# airodump-ng wlan0monmonmon
ioctl(SIOCSIWMODE) failed: Device or resource busy

ARP linktype is set to 1 (Ethernet) - expected ARPHRD_IEEE80211,
ARPHRD_IEEE80211_FULL or ARPHRD_IEEE80211_PRISM instead.  Make
sure RFMON is enabled: run 'airmon-ng start wlan0monmonmon <#>'
Sysfs injection support was not found either.