effective in stopping and preventing crime and violent crime incidents are extremely low but no explanation why the nearly 300 aviation police officers are unarmed. the department is declining to discuss security measures. cnn surveyed large u.s. airports and found chicago's use of unarmed aviation police officers is unique and according to miami security expert wayne black absurd. >> you got sworn law enforcement officers at a u.s. airport trained to hide if there is an attack. that's crazy. airports are targets of terror activity. what will they do if someone runs in with a gun and there is no law enforcement officer there. >> reporter: in october a man caught with these knives attempted to get on the air field and told the officers he knew they were not even armed. the gun issue is part of an on going dispute between the officers and their chief, chicago's aviation police recently took a no confidence vote against edge worth calling