from aircrack site:

Airmon-ng supports mac80211's interface management features (nl80211) using a tool called iw (not to be confused with iwconfig). iw is called automatically by the airmon-ng script, or you might also call it directly to set up monitor interfaces.

Iw is not part of the aircrack-ng suite.


http://www.aircrack-ng.org/doku.php?id=mac80211