I tried making a symbolic link to the airport command in MAC OS X El Capitan, using the command:
airport
sudo ln -s /System/Library/PrivateFrameworks/Apple8
The target directory should be /usr/local/bin/airport
/usr/local/bin/airport
See the article on System Integrity Protection for more information as to why the directories have changed.
sudo ln -s /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport /usr/local/bin/airport