That must be the one I was trying to remember with a former employee being the culprit...I thought he had worked for a freight company but it was US Air...
We were living in Southern CA at the time each of these happened..San Diego, Cerritos, San Luis Obispo...We had a flight operation at John Wayne airport at the time so all of those caught the attention of students/flight instructors and owners of flight schools.
Not a passenger flight, but a UPS freight-only flight crew was attacked in the cockpit by a (disgruntled) UPS pilot seeking revenge while in mid-flight. (The attacking pilot got onboard by pretending to need a lift back to the UPS headquarters.)