Most schedule tweaks are just an adjustment of a few minutes and if booked by a 3rd party (Expedia, Orbits, Priceline, Travelocity, etc.) F9 will notify the travel agent and the travel agent will intern notify the passenger traveling depending on if you gave them a phone, address, and email contact information. If booked directly with F9, more than likely you will receive an email notification unless it is a major schedule change. Then you will receive a phone call from reservations confirming the new schedule.