Most pilots in the U.S. undergo flight training as private individuals with a flight instructor, who may be employed by a flight school. Those who have decided on aviation as a career often begin with an undergraduate aviation-based education. Some pilots are trained in the military and are issued with civilian certificates based on their military record. Others are trained directly by airlines. The pilot may choose to be trained under Part 61 or Part 141 of the FARs. Part 141 requires that a certificated flight school provide an approved, structured course of training, which includes a specified number of hours of ground training (for example, 35 hours for Private Pilot in an airplane). Part 61 sets out a list of knowledge and experience requirements, and is more suitable for students who cannot commit to a structured plan, or for training from freelance instructors. Under Part 61 pilot training, individuals can become a private pilot in about three months and a commercial pilot in as quick as seven months.[6]