Scan for networks:
/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport en1 scan
Sniff:
sudo /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport sniff
Create a symbolic link to the binary so you can easily execute it from your path if you wish.
Resultant sniff will dump the *.cap file in /tmp. Use aircrack-ng to crack the cap file now once you've captured enough IVs and/or handshake.
