mechanic is accused this morning of trying to sabotage one of their own planes filled with passengers. >> investigators say he tried to disable part of the plane's navigation system shortly before it took off from miami international airport. they were onboard to take off. do we know why he tampered with the system but also how close this led this aircraft to potential danger in the air? >> let me set the scene for you. i mean this plane was actually rolling down the runway. there were 150 people onboard, and according to court documents this mechanic allegedly placed foam in a tube that leads to a flight navigation system. luckily, the pilots realized that something was wrong and they aborted that take off. but the man at the center of all this, told investigators that he was upset over a contract dispute between union workers